Make Your Own Glass Cleaner

Today I want to chatter about glass cleaning products that are used on kiln-fired glass, discovering who’s using what and talking about what works and why, and then talk about how you can make or choose the best glass cleaner.

If you’re hoping to read about ordinary household window cleaning products then this blog is unlikely to be of interest, although I will make some passing comments that you may find helpful.

The Motivations

A key motivation is to ask why we pay for a brand name when a generic product or home-made product does the same job, sometimes better, and is cheaper? You might suppose that there’s something special in the branded product but often you’ll discover it’s nothing more than an uninspired formulation of standard raw materials.

Another motivation is to consider why we use glass cleaning product. There are people who use commercial products just as there are others that do not clean their glass before putting it into a kiln. It’s all rather confusing when all you want to do is reduce the incidence of devitrification on you glass masterpiece.

A third motivation is to consider some of the questionable advice found on the Internet when one cleaning product is often recommended in preference for another but without clear reasoning or justification.

Why Bother Cleaning Glass?

The boiled-down essence of “perceived wisdom” is that we need to do whatever is necessary to reduce the number of nucleation sites on the surface of our fusing glass which could lead to devitrification. Basically, it’s any kind of “muck” on the surfaces of your glass that form these nucleation sites that can provoke the devitrification process. The process of devitrification is the result of normally amorphous crystalline glass changing progressively into regular crystalline glass. If you are a keen and enthusiastic learner have a look here to understand more about crystal formation, paying particular attention to the section about “heterogenous nucleation”.

The reason that some people get obsessive about cleaning glass before use is that they believe even the merest hint of a fingerprint or dust on glass will result in devitrification. Others suspect it’s perhaps just a big conspiracy theory, believing that any contaminant on glass will simply burn away, just as white PVA glue or Glastac is supposed to do. Think about both sides of the argument because both sides can’t be simultaneously true but both have some truth to them.

The bottom line is that if we really want to clean our glass then something we must hold in our minds is that a glass cleaner should evaporate and not leave any residues whatsoever if it is to leave your glass in a pure unsullied state.

Who’s Using What?

It’s maybe a good idea to start by finding some examples of who is using what to prepare their glass for firing. We can then look at what’s in those products to understand why they work and why they might not be ideal formulations.

Over here in 2010 we find Spartan Glass Cleaner being recommended by someone from Bullseye in response to a mention of a professional glass cleaner from Bohle being used by someone who has a problem. This forum thread is particularly interesting because the advice is well-meant but smacks of “product placement” because Bullseye sell Spartan Glass Cleaner.

Elsewhere I see another “product placement” in the same forum in 2010 where a lack of understanding that “rubbing alcohol” and “denatured alcohol” are not the same thing leads to another “product placement” for Spartan Glass Cleaner, again by someone from Bullseye. Overall, this forum thread gets my vote for whacky advice and mis-information.

But we do now have two named commercial products and two “alcohols” to start the ball rolling for our investigation…

  • Bohle glass cleaner
  • Spartan Glass Cleaner
  • rubbing alcohol
  • denatured alcohol

Let’s look at them in more detail.

If you look for Bohle glass cleaner you find you’ll find that they actually produce more than one product. Find their safety data sheets here and study them, looking for the section in which you find their ingredients. You will find their glass cleaners contain isopropyl alcohol and a surfactant called 2-butoxyethanol. We will individually consider these chemical components later.

We now move on to the aforementioned “Spartan Glass Cleaner” and you will also find that Spartan Chemicals make several glass cleaners. The particular Spartan product that Bullseye sell here seems to be this product from Spartan Chemical and lower down on the same page you’ll find the safety data sheets in three languages, the American language version being here. From the manufacturer’s safety data sheet we learn that Spartan Glass Cleaner contains mostly water, some isopropanol and a little acetic acid. Curiously the safety data sheet for the product suggests a “floral fragrance” which I can only assume means the addition of a small amount of unlisted perfume to mask the acrid smell of acetic acid.

Rubbing alcohol has been mentioned in the forums. It has a strange name because it describes the intended use rather than a specific chemical. So, as you’ll find at Wikipedia’s page for rubbing alcohol it’s likely to be some water with either isopropyl alcohol or ethanol with the possible addition of various additives, some some of which may make it taste bitter and undrinkable and others that have mild medicinal qualities. This lends some credence to a forum contributor here that says rubbing alcohols “sometimes contains impurities, like oils”. Therefore, in summary, rubbing alcohol is an ill-defined product that is mainly made using alcohols that will quickly evaporate but may also contain additions that will not evaporate after cleaning our glass, leaving a small amount of residue. These ill-defined additions are a possible trigger for devitrification if they do not cleanly burn off in a kiln.

Denatured alcohol is also known as methylated spirits and is a mixture of chemicals though typically it is ethanol that dominates, with the addition of some water. It is difficult to pin down precisely what the formulation is because many possible additives are added to the ethanol to make it taste bitter and undrinkable. Whatever the mixture, the alcohols will evaporate completely and quickly because they are volatile, just as they will do for rubbing alcohol. Other additive, such as dyes and bitter-tasting denatonium (as with rubbing alcohol) are a possible trigger for devitrification if they do not cleanly burn off in a kiln.

Domestic Window Cleaning Products

Here I just want to make a few passing comments about what we might call a general purpose window cleaning products. By this I mean something you’d choose to routinely use in a domestic setting.

My first observation is that I don’t really see how Spartan Glass Cleaner can be considered to be special. It certainly does not appear to be specifically designed for our precious fusing glass. More to the point, the formulation appears to be what one might expect from a general purpose window cleaning product (by virtue of the vinegar and having a fragrance) and indeed it seems to be sold by Spartan Chemicals as a general purpose glass and window cleaning concentrate.

A similar observation can be made regarding the Bohle glass cleaners as they too do not appear to be specifically designed for our precious fusing glass.

There is however one very useful comment mentioned here that warns us to avoid extremes of pH (meaning acidity or alkalinity) because they can attack metallic structures such as lead or zinc cames. In other words, glass cleaners that contain ammonia or vinegar at significant concentrations should be avoided. However, because we spray our windows with products that contain only low concentrations of ammonia (or vinegar) then wipe it all away within minutes I fail to understand how any damage can be done to the glass itself and there is little time available to corrode metal work.

Looking More Closely

We have now looked at four products that have been mentioned in forum threads and I’m sure that many others could be added. But let’s press on to the interesting stuff. It’s time to consider the key chemicals from which they are made so that we can better understand what’s good, what’s not and why.

Water is a common ingredient. As we all know, pure water boils at 100 °C and should be neither acidic nor alkaline. Water is probably the most familiar solvent we use and it will not easily cause our glass to devitrify. It is a cheap chemical because it’s so abundant, even if we choose to pay extra for deionised water or even more for distilled water because we don’t have a nice clean soft water supply coming from out taps (American: faucets). The only concern here is the use of hard water because of the dissolved minerals which might come out of solution when cleaning glass because tiny mineral particles can act as nucleation points for devitrification. With regard to distilled vs. deionised water I note that although distilled water is very pure, it should be noted that deionised water has the ionic mineral components removed so is much cheaper to produce and just as usable as distilled water for cleaning glass. Sometimes spending that extra money doesn’t really give you any significant advantage.

Isopropyl alcohol has many chemical synonyms such as isopropanol, propanol and propan-1-ol. We’ve already seen isopropyl alcohol mentioned in the safety data sheets for both of the commercial products as well as for the rubbing alcohol (and possibly for denatured alcohol). So is important we know more about this particular alcohol. In essence, isopropyl alcohol is a pure chemical, not a commercial formulation, which means we can know exactly how it behaves. It is volatile with a boiling point of 82.6 °C which means it evaporates quickly and completely. It is neither an acid nor an alkali so it will not attack glass. It is an effective solvent in many situations and is also cheap to manufacture so you will find it being used in many diverse cleaning products. These are all good characteristics for a glass cleaner, explaining why each of our four example products involve isopropyl alcohol.

2-butoxyethanol has many synonyms of which 2-butoxyethan-1-ol is its favoured chemical name. In essence it’s another pure chemical, not a commercial formulation, which means we can know exactly how it behaves. It is a non-volatile solvent of low toxicity that has mild surfactant properties and has a mild sweet smell. In other words, it’s a gentle cleaning agent that doesn’t evaporate quickly so is useful for cleaning mucky glass. It has a boiling point of 171 °C which means that any of it that is not cleaned off our glass ought to evaporate completely in a kiln. Surfactants are something we’re more familiar with in washing-up liquid and other “harsher” household washing and cleaning products and the reason they’re often used is because they’re good at “lifting dirt”.

Acetic acid is also known as ethanoic acid and when diluted we know it as vinegar. When in Britain, be sure to add some to your fish and chips (American: fries) if it’s of the malted vinegar variety. Acetic acid has a boiling point of 116 °C which means it should evaporate completely but not very quickly but we must remember that acetic acid is mixed with plenty of water to form what we know as vinegar. Vinegar has been used to clean things for time immemorial and is used in some glass cleaning formulations such as Spartan Glass Cleaner as promoted by Bullseye as well as domestic products such as Windowlene in the UK. It is a cheap and abundant chemical. It is a weak acid being used in small quantities, and because we don’t spend hours cleaning a piece of glass, it is unlikely to cause any problems for our fusing glass surfaces.

Though not mentioned in the four products we’ve been looking into, it would be remiss of me to ignore ammonia which is a synonym for household ammonia and ammonium hydroxide. It does happen to be used in a Spartan glass cleaner promoted as being “fortified with ammonia” and you’ll find the MSDS here. But I digress. Ammonia is volatile and has a boiling point of around 27 °C and is a commonly used in small quantities, diluted in water, as a solvent in some household window cleaning products. Only because ammonia tends to be used in small quantities within window cleaning products, and because we don’t spend hours cleaning a piece of glass, can we assume the ammonia it is unlikely to cause any problems with our fusing glass. It just smells absolutely horrible.

We can not identify the un-named but implied fragrance perfume in Spartan Glass Cleaner and can only assume that if it’s not causing Bullseye any problems. We can however guess that it’s probably some kind of organic molecule (or mixture) that successfully burns off in a kiln. But, if we are worried about devitrification and want to avoid contaminating the glass then shouldn’t we also want to avoid things like fragrance chemicals that aren’t needed to clean our glass? This is an interesting concept to consider! All I can suggest is that the only logical reason to add a perfume to a cleaning product is to mask the smell of something unpleasant – like vinegar or ammonia.

And finally, I have one more chemical that deserves a mention because it’s rarely mentioned. It’s called acetone and is also known as propanone. Add some colour and perhaps some fragrance and we call it nail polish remover. Acetone is very volatile and has a boiling point of 100 °C which means it will quickly evaporate and leave no residues. It is neither acidic or alkaline so will not attack glass. The colorants and perfumes added to nail polish remover make it impure and therefore less desirable than pure acetone. The only link on the Internet I can recommend reading that knowledgeably relates to the use of acetone to clean glass is here.

Looking Wider

Having discovered and learned a little about chemicals that are commonly used, it’s time to trawl the Internet for more examples of what people are using to clean their glass. The best source I encountered comes from a long forum thread here at Fused Glass in 2008 that reveals many examples of what people do to clean their glass.

What follows in this section is a brief summary of what caught my eye in that forum thread and I don’t suppose attitudes and behaviours have changed much in the succeeding decade.

One person uses distilled water and vinegar, commenting that they use distilled water due to having a hard water supply. Avoiding hard water is a good idea because of the dissolved mineral that might come out of solution, leaving scummy particles that might just provoke the nucleation which cause devitrification. Again we see readily available vinegar being used. What is not clear is whether the water and vinegar are separate cleaning steps or whether they are mixed together. I personally would hope this person used the vinegar as a first step then rinsed using the distilled water.

Another person uses hot water with a small amount of soap. This sounds reasonable because the soap and water will be effective with most kinds of contamination. The kind of soap is not mentioned though some (such as washing-up liquid) often contain surfactants (like the 2-butoxyethanol used in the Bohle glass cleaner) whereas others (particularly hand-made soaps) may contain an excess of oils and fats and might therefore leave a thin greasy residue which ought to burn off in the kiln. But for a good cleaning regime it is important to ensure that soap residues are completely removed with a thorough rinse.

Another related comment in the forum thread is the use of warm water with a little dish soap followed by rubbing alcohol. I like this regime better than the previous example because there is a rational two-step regime. Not only does the alcohol rinse away any remaining dish soap but it also serves as a different kind of solvent. The only problem I have with this regime is that it is two steps which implies lots of time and effort.

One contributor reveals what is, in effect, the reverse process, saying ” I use alcohol, then I wash it is very hot water & Dawn dishwashing soap”. Dawn dishwashing soap is what I’d call washing-up liquid, probably a perfumed, mixture of chemicals that includes a surfactant that should be well suited to removing a variety of contaminants. However, this regime would be more reliable and more effective if the alcohol was the second stage, if only to ensure that the washing-up liquid residues are completely removed by the alcohol wash.

And then there’s someone who uses an undefined alcohol and another who uses isopropyl alcohol. As we’ve seen with the Bohle and Spartan glass cleaners, alcohols are widely used because good for cleaning glass.

A curious comment is from someone who says they attended a workshop at Bullseye and they use a mixture of 50% white vinegar and 50% denatured alcohol. This seems to be at odds with what the people from Bullseye have been saying in the forum threads I mentioned at the top of this blog though one might rationally argue that this forum thread is from 2008 whereas the people at Bullseye were recommending Spartan’s products in 2010. But regardless of this observation, the quantity of white vinegar being used seems to be rather excessive, even when we recall that vinegar is acetic acid diluted with lots of water. A small quantity of the white vinegar added to the alcohol would be just as effective and would not smell so horrible. In fact, I’d hazard a guess that omitting the vinegar would be equally effective.

Of course, there are also some people who are using ordinary domestic window cleaning products. But, to be blunt, is that not what the Bullseye recommended Spartan glass cleaner and the Bohle glass cleaner seem to be?

And, for completeness, I should mention that there were some people in the forum thread who’ve been told not to bother cleaning glass because the contaminants will all burn off. This is questionable advice because only the chemicals and contaminants that cleanly burn or evaporate will disappear and not cause a problem. Try burning off particles of grit for example!

 Make Me Laugh

The quote below from the same forum thread at Fused Glass and I find interesting because it reminds us to question what we are told, do our own research and to not assume that a supposed expert is always right, whether the advice is from a face-to-face encounter with a real person or via the Internet.

I took classes from a ” prominent teacher ” who also gave incorrect information….lots of it actually.  Forums such as these are an excellent source of information and have taught me MORE than the prominent teacher.”

If you’re now of the opinion that forums are good and experts are unreliable then consider the advice given here at the Glass Fusing Made Easy web site. It tells us…

Detergents, dish soaps, multi-purpose cleaners, some window cleaners, ammonia and even denatured alcohol should not be used to clean glass.
The Bullseye site suggests that you purchase a cleaner called Spartan Window Cleaner.

Though well-meaning, it’s rather lacking in rigour. Where is the justification and reasoning to support any of this advice? More to the point, there’s a bland assumption that Spartan Window Cleaner must be a good choice because Bullseye recommend what they sell.

Remember folks, I regularly and deliberately tell you to question everything you read on the Internet. I even tell you to not assume I know what I’m talking about. Don’t take my advice without question and likewise don’t take advice from anyone else without question. Think things through and make your own decisions.

My Recommendations

No matter what you decide to use for cleaning glass, if indeed you choose to clean your glass, just make sure the glass is cleaned thoroughly then buffed until it is dry. If you stop buffing when the glass is still wet then the contaminants dissolved in your glass cleaning liquid will be left behind (nicely smeared) on the glass surface when the remaining glass cleaning liquid evaporates.

Use a lint-free cloth if you can for your drying and buffing, but if you can’t then try using good quality paper kitchen towels instead. Cheap paper kitchen towels can leave a residue of paper dust so try not to use such products.

If you find that a piece of glass does not seem to be completely clean after trying to clean it with one kind of cleaning product then repeat using the same cleaning product if it previously made some good progress.

Do remember that you can choose a different cleaning product for your second cleaning attempt, especially if the first cleaning product is having difficulties with the contaminant. Different cleaning products have different capabilities because they contain different solvents.

If you are going to use a cleaning product that contains a soap or surfactant then consider a second rinsing to be sure the soap residue is removed. Be especially aware that some kinds of soap (particularly “super-fatted” hand-made soaps) may leave a thin greasy residue on the glass you just cleaned.

I am an advocate of using pure solvents that are devoid of non-essential additives. I therefore tend to use neat isopropyl alcohol or neat acetone as my cleaning solvents. But remember that I’m not afraid to pre-clean mucky glass with soap and water. Of all the recommendations I give you in this section, this is the paragraph I want you to remember!

Isopropyl alcohol and acetone are volatile and flammable. Take care when you use cleaning products that contain these chemicals. Take care with acetone near plastics as it’s good at melting some of kinds of plastic!

I believe that touching glass with a finger is overstated as a risk for devitrification if your hands are reasonably clean. I have found that white PVA glues are far worse than fingerprints for causing devitrification. So the simple advice here is to try washing your hands before you work with your glass!

And finally, don’t get obsessive about glass cleaning. Just use a quick and effective cleaning regime that works.

Choose Your Cleaning Product

You should now be aware that several different chemicals can be found in glass cleaning products and that you now have an idea of what other people are using. You now also know that there’s nothing particularly special about expensive proprietary commercial glass cleaning products. You also know that water (soft, deionised or distilled), acetone and isopropyl alcohol are the key solvents you need to consider.

Ideally, you will need to find a local supplier of “industrial chemicals” or maybe “industrial solvents” to buy your distilled or deionised water, isopropyl alcohol or acetone, but they should cost you a lot less that buying them from your local stained glass supplier.

An example supplier that I’ve mentioned in the past is APC Pure. I don’t mention them because I work for them or get any commission from them. I simply mention them because they’re local to where I live and they’re an example of the kind of company you should be looking for. They also sell on eBay as do other chemical suppliers. Seek and ye shall find though it’s harder in some countries than others.

If you choose to buy some isopropyl alcohol you should now realise that you can, if you wish, do things lilke dilute it with water and perhaps add some white vinegar to make your own version of the Spartan glass cleaner type of product. But I find it is best when the isopropyl alcohol is used at full strength and pure because it evaporates quickly and cleanly.

You may also choose to buy some acetone. I find it will deal with contaminants that isopropyl alcohol struggles with (and vice versa). I always use it neat as it evaporates very quickly and cleanly.

Don’t waste your money on branded products when you know about cheaper and better alternatives!

A Curious Detour

Although a detour, it is interesting to look here because it says

“I’ve been told that [Fusemaster] Superspray has a shelf life of about 1 1/2 years. If that is true, and yours is fairly old, that might be the cause [of devitrification]”.

Well, a search for the MSDS for this devitrification spray tells me it’s pretty-much powder frit added to ethyl alcohol with a tiny amount of isopropyl alcohol with some methyl isobutyl ketone as a surfactant. What struck me as interesting is that the three chemicals used to “carry” the glass powder seem to be remarkably similar to what we’d expect for a glass cleaning product. I can see the logic for using the two alcohols but I’m baffled why the surfactant is used, other then perhaps they are simply mixing a bought-in glass cleaning product and mixing it with clear glass powder frit.

But back to the context of the original forum posting… Call me stupid if you like but I don’t think powdered frit has a shelf life. And I don’t ever recall seeing a “Best before” date on any window cleaning product I’ve ever seen in the past. In other words the devit spray can’t be the cause of the devitrification.

Another example of well-meant poor advice I think!

And Finally

That’s all my chatter for today so all that remains is to remind all you “do it yourself” fans that I’ve already done postings that tell you how to make your own copper patina solution, safety flux and glass polishing compound.

Best wishes and a happy new year to you all.

Posted in Glass Cleaning, Money-saving ideas | Tagged , , | Leave a comment

Undercut Your Dichro

Today’s blog is mercifully short. There’s no maths or science and it isn’t even a fantastic new discovery that will change the world. It’s more of a helpful tip to those who’ve maybe not realised there’s an answer to the following problem:

When firing a piece of  clear-backed dichroic glass metal side down over a base of some other kind of glass we can produce a three-dimensional “well” effect. The problem is that it results in a messy-looking metal edge when we take it out of the kiln.

On the right is a picture of what I mean.

The left side illustrates what you can expect to happen without today’s tip. The right side shows that the problem can be managed, albeit not perfectly in this particular example.

Although I earn no gold star for excellence with this particular experiment you can at least see there’s a distinct improvement. The questions to be answered are how the problem arises and how the problem can be eliminated or at least mitigated.

The problem arises because the clear-backed dichroic glass sinks into the glass base during the fusing process and leaves behind some of the metal layer at the edges.

The answer to this problem is simple. Just grind away the dichroic metal layer from the edges of the piece of dichroic glass. This can be done very quickly with diamond pads for untextured dichroic glass but will be more fiddly with textured surfaces.

To illustrate what you are aiming for, look at the diagram below. The lower area represents the base glass, the upper area represents the clear dichroic glass and the thick line represents the metal layer of the dichroic glass.

Notice the angled undercutting at the lower edges of the dichroic glass and how some of the metal layer gets removed as a consequence. From this you will realise it’s not the angle of the undercutting that is important but the amount of metal layer that gets removed. Having said that, you’ll get better control over how much metal you remove with a reasonable angle that you’ll achieve with a really shallow angle.

Exactly how much undercutting is needed to eliminate the problem primarily depends on the thickness of the dichroic glass layer. I also expect (but have not checked) that the amount of undercut will also depend on whether you are using a microwave kiln or a “proper” kiln. Start with a couple of millimetres of undercutting for your first experiment. Let practise and experience become your teacher.

That’s all for now. Happy fusing.


Posted in Dichroic Glass, Microwave kiln | Tagged , , | Leave a comment

The Glass Bookshelf

For your enjoyment I have gathered together details of well over a hundred old books that relate to glass in some form or another, all of which are easily accessible over the Internet.

Whether it’s the glass sands of Kentucky, glass manufacture, glass painting, old trade catalogues, collecting glassware, making laboratory glassware, old Church windows or one of the many other strange topics relating to glass, there’s surely something for you somewhere in the list. I hope you find something that tickles your fancy.

Downloadable Book Lists

Although you’ll find the book list below within this blog I’m sure that some of you will want to “do your own thing”. So, I’ve created three alternative files that you can download and fiddle with. You could then sort your copy of the book list by title, date or author, improve the topic lists, add more books, or whatever else you might fancy doing. Make the downloaded files your own personalised bookshelf!

Beware: Although the file names below have familiar file types like “.doc” and “.pdf”, they aren’t what they seem to be. I’ve had to do some simple “trickery” to enable you to download file types that WordPress, in its infinite wisdom, has chosen not to allow. So, be sure to read the text that follows the filenames before downloading them!

  • Bookshelf-rtf.doc   Actually this is not a “.doc” file, it’s a “.rtf” file. I had to rename it from “Bookshelf.rtf” to “Bookshelf-rtf.doc” before WordPress would to allow me to share it with you. So, please rename it back to “Bookshelf.rtf” once you’ve downloaded it. Let me explain… Unlike “.doc” files, “.rtf” rich text files are Microsoft’s only official “portable” file format for word processing documents. This means it can be loaded into many kinds of word processor applications and not just Microsoft Word. Use this file if you want to maintain and use the book list within your word processor. If this doesn’t work for you then try the Bookshelf.xls file format in your spreadsheet application and copy the table out of there into your word processor application.
  • Bookshelf.xls   This spreadsheet file really is an “.xls” file and it is saved in an old version of Microsoft Excel format so you don’t need Microsoft’s latest and greatest bloatware to use this file. It should work with some other spreadsheet applications too.  Use this file if you want to maintain and use the book list as a spreadsheet. If this doesn’t work for you then try the Bookshelf.tsv file instead (see below).
  • Bookshelf-tsv.pdf   Actually this is not a “.pdf” file, it’s a “.tsv” file. I had to rename it from “Bookshelf.tsv” to “Bookshelf-tsv.pdf” before WordPress would to allow me to share it with you. So, please rename it back to “Bookshelf.tsv” once you’ve downloaded it. This is a “tab separated variable” file that can be loaded into most kinds of spreadsheet application, word processors and even some database applications. Treat this as your “last chance” file format because you’ll probably need to do some messing about to get what’s loaded into a nice useful state. Despite this it’ll be much quicker than trying to type everything manually.

If you struggle and fail with all three file formats, or have a particular need for some other file format for use on something other than a Microslop Windoze machine then do let me know and I’ll try to help.

Some Notes

The Title, Author and Date columns should uniquely and correctly identify each book but in some cases notes are added in square braces within the Title column to indicate something noteworthy, such as telling you that a different edition elsewhere in the table. Where a the title of a book title contains an ellipsis it is an indication that the full title was so long and verbose that it has been truncated. There were occasions when I reckoned the book details didn’t seem to be correct (for whatever reason) so occasionally you’ll find that information about titles, authors or dates in my table are not quite what you’ll find at

The Topics column gives an indication of what kind of information is found in the books and can be rather vague. Sometimes I’ve given you what the archivist recorded as the topics, if anything. Sometimes I’ve added to their topic lists and sometimes I had to create the topic list myself. A consequence is that the list of topics can be rather erratic but better than a poke in the eye with a blunt stick.

The Location column contains one or more URL links that take you to a web page where you can download the book. It’s perhaps sad to note that many of the old books have been digitised multiple times whereas many other old books remain only as “hard copy”. After awhile I got bored with finding alternative sources for the books so stopped bothering.

In all cases, visiting the URL will reveal a download available in PDF format. Often there are other file formats available as well. Alternative formats might be more suitable for use on a Kindle or mobile phone, for example. If you intend to download a copy of all the books in PDF format then you will need about 4GB of free disk space.

Bear in mind that copyright laws in different countries are not the same. Distributing this list of books and their locations will not breach any copyright but distributing the scanned book images and expecting payment might.

Here are the books I’ve found so far. There are even more out there!

Oh, and sorry about the bad layout of the table. Despite messing around with the undelying HTML I can’t force WordPress to present the information tidily.

Title Author Date Topics Location
The Glass Worker, vol 4 no 46 (Jun 1907) and vol 4 no 48 (Aug 1907) Amalgamated Glass Workers’ International Association of America 1907 Glass Industry, Industrial
A Notable Collection of Ancient Egyptian, Greek and Roman Glass, Persian Potteries, Greek Painted Vases … Anderson Galleries Inc. 1924 Mr. Azeez Khayat, Catalogue
Stained glass of the middle ages in England & France Arnold, H. 1913 Glass painting and staining, Art, Mediaeval, England, France. and similar at
Arts and crafts essays

[in which many subjects are covered, including Stained Glass by Somers Clarke, pp96-105)

Arts and Crafts Exhibition Society 1893 Arts and crafts movement, Decorative arts
History of the Worshipful Company of Glaziers of the City of London, otherwise the Company of Glaziers and Painters of Glass Ashdown, C. H. 1919 Company of Glaziers, London, Guilds.
Twelfth Census of the United States: Census Bulletin no 228: Manufactures: Glass Manufacture Austin, S. P. 1902 Glass industry, Census
The painter, gilder, and varnisher’s companion containing rules and regulations in everything relating to the arts of painting, gilding, varnishing, and glass staining … [See also 1867 edn] Baird, H. C. (Pub.) 1850 Painting, Industrial, Gilding, Varnish and varnishing, Receipts.
The painter, gilder, and varnisher’s companion containing rules and regulations in everything relating to the arts of painting, gilding, varnishing, and glass staining …, 10th Edn.

[See also 1850 edn]

Baird, H. C. (Pub.) 1867 Painting, Industrial, Gilding, Varnish and varnishing, Receipts.
Schwäbische Glasmalerei Balet, L. 1912 Glass painting and staining
A Treatise on Painted Glass, Shewing its Applicablity to Every Style of Architecture Ballantine, J. 1845 Glass painting and staining
American glassware, old and new: a sketch of the glass industry in the U.S. and manual for collectors of historical bottles Barber, E. A. 1900 Glass manufacture, Glassware
Spanish Glass in the Collection of the Hispanic Society of America Barber, E. A. 1917 Glassware, Spain
English table glass

[See also later edition]

Bate, P. H. 1905 Glassware, Tableware, England
English table glass

[See also earlier edition]

Bate, P. H. 1913 Glassware, Tableware, England
President’s Address on “Stained Glass and Painted Glass” , in Transactions of the Bristol and Gloucestershire Archaeological Society, Vol 22. Editor: Rev. C. S. Taylor, Bazley, G. S. 1899 Periodical. Antiquities, Bristol and Gloucestershire, Glass painting and staining.
Catalogue Belcher Mosaic Glass Co. 1886 Mosaics, Glass painting and staining, Glass, Coloured–Catalogues
A lecture on stained glass Bell, R. 1922 Glass painting and staining
Sir Henry Bessemer, F. R. S. An autobiography

[Chapter VIII relates to glass processing]

Bessemer, H., Sir. 1905 Glass manufacture, Industrial processes, Autobiography
Elements of Glass and Glass Making Biser, B. F. 1899 Glass manufacture
The Art of Glass: shewing how to make all sorts of glass, crystal and enamel, likewise the making of pearls, precious stones, china and looking-glasses … [Translation of: De l’art de la verrerie] Blancourt, H. 1699 Glass manufacture, Enamels & enamelling, precious stones, minerals, optical glass, glass eyes
A handbook of laboratory glass‐blowing Bolas, B. D. 1921 Glass blowing and working, Glass manufacture, Technique
A memoir on British resources of sands suitable for glass‐making Boswell, P. G. H. 1916 Glass manufacture
Japanese Enamels: With Illustrations from the Examples in the Bowes Collection Bowes, J. L. 1886 Enamels and enamelling, Cloissonné, Shippo, Japan
Notes on Shippo: A Sequel to Japanese Enamels Bowes, J. L. 1895 Enamels and enamelling, Glass manufacture, Cloissonné, Shippo, Japan
Glass cup plates: A Guide to Collectors Burns, C. 1921 Glassware
Storied windows: A traveller’s introduction to the study of old church glass, from the twelfth century to the Renaissance, especially in France Bushnell, A. J. 1914 Glass painting and staining, Cathedrals, Renaissance, Mediaeval, France
Catalogue of the collection of stained and painted glass in the Pennsylvania museum Bye, A.E. 1925 Glass painting and staining, Philadelphia Museum of Art
General Electric Lighting Canadian General Electric Company 1949 Lighting, Glassware, Commercial & industrial equipment.
Stories of Industry, 1891, Vol 1

[Vol 2 relates to clothing and foodstuffs]

Chase, A. & Clow, E. 1891 Industrial Arts, Minerals, Industrial Processes, Machinery & Equipment, Glass Manufacture, Pottery manufacture
Art glass metals Chicago Metallic Sash Company 1925 Art glass, Came, Stained Glass, Glazing accessories, Trade, Catalogues
Five Black Arts: a popular account of the history, processes of manufacture, and uses of printing, pottery, glass, … Coggeshall, W. T. 1861 Printing History, Porcelain History, Glass Manufacture History, Iron Industry and Trade History, Gas Manufacture and Works History
The Crown Glass Cutter and Glazier’s Manual: Glass cutter, glazier & stained glass maker in ordinary to the king for Scotland Cooper, W. 1835 Glass manufacture
Windows: A Book about Stained & Painted Glass

[See also later edition]

Day, L. F. 1897 Glass painting and staining and also
Windows: A Book about Stained & Painted Glass

[See also older edition]

Day, L. F. 1909 Glass painting and staining
Catalogue of an Exhibition of Stained Glass from the XIth to the XVIIIth cent Demotte Inc. (Pub.) 1920 Glass painting and staining
Glass Dillon, E. 1907 Glass, Glassware
A history of English glass painting, with some remarks upon the Swiss glass miniatures of the sixteenth and seventeenth centuries Drake, M. 1912 Glass painting and staining
Valuable secrets in arts, trades, &c.: selected from the best authors and adapted to the situation of the United States [See also other editions] Duyckinck, E. (Pub.) 1802 Receipts, Workshop recipes, Industrial art, Art technique
Valuable secrets in arts, trades, &c.: selected from the best authors and adapted to the situation of the United States. [See also other editions] Duyckinck, E. (Pub.) 1809 Receipts, Workshop recipes, Industrial art, Art technique
Valuable secrets in arts, trades, &c.: selected from the best authors and adapted to the situation of the United States [See also other editions] Duyckinck, E. (Pub.) 1816 Receipts, Workshop recipes, Industrial art, Art technique
Ancient stained and painted glass Eden, F. S. 1913 Glass painting and staining, History
The collection of heraldic stained glass at Ronaele Manor, Elkins Park, Pennsylvania, the residence of Mr. & Mrs. Fitz Eugene Dixon Eden, F. S. 1927 Dixon, Fitz Eugene, Glass painting and staining, Heraldry, Devices
Graeco‐Egyptian Glass Edgar, C. C. 1905 Ancient Glassware, Greco-Egyptian Glassware
The Origin of Glass Blowing in American Journal of Archaeology, Vol XX, pp 134-143 Eisen, G. 1916 Glass blowing
Antique Glass, in The Art Bulletin, Vol2: pp 87-119. Eisen, G. A. 1919 Glass painting and staining
Stained glass windows: An essay with a report to the vestry on stained glass windows for Grace Church, Lockport, New York Faber, W. F. 1900 Grace Episcopal Church (Lockport, N.Y.), Church records and registers, Glass painting and staining, Genealogy
Notes on the Painted Glass of Canterbury Cathedral Farrar, F. W. 1897 Canterbury Cathedral, Glass painting and staining
Glass Manufacture and the Glass Sand Industry of Pennsylvania Fettke, C. R. 1919 Glass, Glass manufacture, Glass Sands, Pennsylvania and at
The drama of glass [Publication date uncertain but there are references to 1893 within text] Field, K. 189‐ Glass manufacture
Hiersemanns Handbücher, Vol VIII: Handbuch der glasmalerei für forscher, sammler und kunstfreunde, wie für künstler, architekten und glasmaler Fischer, J. L. 1914 Glass painting and staining.
Laboratory manual of glass‐blowing Frary, F. C. 1914 Glass Manufacture, Glass-Blowing, Scientific Glassware, Laboratory, Technique
An Essay on the Art of Painting on Glass from the German of Emanuel Otto Fromberg Fromberg, E. O. 1851 Glass painting and staining
Rudimentary Essay on the Art of Painting on Glass from the German of Emanuel Otto Fromberg Fromberg, E. O. 1857 Enamel and enamelling, Glass painting and staining, Glass manufacture chemistry
Histoire de la Verrerie et de l’Émaillerie Garnier, E. 1886 Glass painting and staining, Enamel and enamelling
Street Lighting Glassware General Electric Company 1925 Street lighting, Glassware
Metal Casements and Frames, Wrought Iron George Wragge Ltd. 1948 Steel windows, casement windows, Trade catalogue
Rudimentary treatise on the art of painting on glass or glass-staining: comprising directions for preparing the pigments and fluxes … Gessert, M. 1851 Enamel and enamelling, Glass painting and staining and similar at
A booke of sundry draughtes, principaly serving for glasiers … Gidde, W. 1615 Decoration and ornament, Glass painting and staining, Enamel and enamelling
Stained Glass and Metal Work of Every Description for Churches, Chapels, etc.: Catalogues, Photographs and Special Designs with… Gorham Manufacturing Co. 1895 Trade catalogue, Stained Glass, Art Glass, Ecclesiastical, Windows, Memorials,
Le Vetrate di S. Francesco in Assisi – Studio Storico Iconografico Guisto, E. M. 1911 San Francesco Church (Assisi, Italy), Glass painting and staining
Old English glasses. … glass drinking vessels in England, from early times to the end of the eighteenth century Hartshorne, A. 1897 Glassware, Great Britain, Old English Glass, Jacobite Glass, Irish Glass, Wine in England
An history of the origin and establishment of Gothic architecture : comprehending also … Hawkins, J. S. 1813 Cesare Cesariano, Glass painting and staining in Middle Ages, Gothic Architecture
Rich cut glass and fine china Higgins & Seiter 1903? Trade Catalogue, Porcelain, Glass, Cut Glass
General catalogue of the manufactures of Adam Hilger, Ltd Hilger, A. 1913 Wavelength Spectrometers, Optical instruments, Scientific instruments
Stained glass as an art Holiday, H. 1896 Glass painting and staining
A practical manual of the collodion process : giving in detail a method for producing positive and negative pictures on glass and paper, ambrotypes, printing process, also patents… Humphrey, S. D. 1857 Collodion process, Collodion process, Photography, Photographic chemistry
Invisible Glass Windows: A Dramatic New Merchandising Force

[An example of this can be seen in Byram Street, Huddersfield, West Yorkshire]

Invisible Glass Company of America 1937 Trade catalogue, Store front, Display window.
Encyclopaedia of chemistry, theoretical, practical, and analytical, as applied to the arts and manufacturers J. B. Lippincott & Co. 1877 Chemistry, Technical, Art, Manufacturing
Glass: Interesting Facts connected with its Discovery and Manufacture J. E. Caldwell & Co. 18?? Glassware, Trade Catalogues, Glass History, Cut Glass
Priced and Illustrated Catalogue of Optical Instruments, Made, Imported and Sold, Wholesale and Retail James W. Queen & Co. 1870 Trade Catalogue, Optical Instruments, Lenses, Spectacles, Eye-Glasses, Telescopes, Camera Obscura, Microscopes, Dissection Tools, Biological Specimens, Geological Specimens
Reminiscences of glass‐making, 2nd Edn. Jarves, D. 1865 Glass Manufacture, Glass History, Chemistry, Workshop, Recipes
L’art de la Peinture sur Verre et de la Vitrerie Le Vieil, P. 1774 Glass painting and staining
Valuable secrets concerning arts and trades

[Note: T. Hubbard is the publisher, not the author]

Leather, V. 1795 Decorative Arts and similar at
Department Store Mechandise Manuals: The Glassware Department Lehmann, M. A. 1918 Glassware, Glassware manufacture
Old glass and how to collect it

[See also later editions]

Lewis, J. S. 1900 Glass collecting, Glassware
Old glass and how to collect it

[See also earlier edition]

Lewis, J. S. 1916 Glass collecting, Glassware
Old glass and how to collect it

[See also earlier editions]

Lewis, J. S. 1950 Glass collecting, Glassware
Flat Glass Libbey‐Owens‐Ford Glass Company 1924 Glass, Glazing, Trade Catalogue, Glass manufacture
Experimental Glass Blowing for Boys Lynde, C. J. 1920 Glass blowing and working, Laboratory
Fifty years of glass making, 1869‐1919 Macbeth‐Evans Glass Company 1920 Glass Manufacture
Glass and glass manufacture Marson, P. 1919 Glass, Glass manufacture
Optical measuring instruments, their construction, theory, and use Martin, L. C. 1924 Optical Instruments, Optical devices, Optics, Engineering
American glass McClinton, K. 1950 Glassware
Les Vitraux Merson, O. 1895 Glass painting and staining and also at
Fifteenth-Century Glass in The Chancel Window of St. Peter Mancroft, Norwich Meyrick, F. 1911 St. Peter Mancroft Church (Norwich, England), Glass painting and staining
Stained glass Miller, E. 1900 Glass painting and staining
Window Glass in the Making: An Art, A Craft, A Business Monroe, W. L. 1926 Glass, Glazing, Industrial Arts
The secret of pictorial art, or Self instructor in painting on glass, china, satin, and paper … Morse, D. D. 1879 Decorative arts, Decoration and ornament, Painting, Drawing
International Art Glass Catalogue: Art and bevelled glass in all its branches: church, memorial, society and domestic windows, Art Nouveau, prism, mitre beveled plate, leaded bevel, etc. [See also 1924 edition] Nat. Ornamental Glass Mfrs Assn of the US and Canada. 1914 Glass painting and staining, Catalogues, Trade catalogue, Art glass
Revised International Art Glass Catalogue: Art and bevelled glass in all its branches: church, memorial, society and domestic windows, Art Nouveau, prism, mitre beveled plate, leaded bevel, etc. [See also 1914 edition] Nat. Ornamental Glass Mfrs Assn of the US and Canada. 1924 Glass painting and staining, Catalogues, Trade catalogue, Art glass
Ancient painted glass in England 1170-1500 Nelson, P. 1913 Glass painting and staining, England, Mediaeval.
A descriptive catalogue of the glass vessels in the South Kensington museum Nesbitt, A. 1878 Glassware
Glass Nesbitt, A. 1878 Glass, Glassware, History, Glass Composition
Geschichte der Schweizer Glasmalerei Oidtmann, H., Dr. 1905 Glass painting and staining
Die Rheinischen Glasmalereien vom 12. bis zum 16. Jahrhundert, Erster Band Oidtmann, H., Dr. 1912 Glass painting and staining
Modern optical instruments and their construction Orford, H. 1896 Optics, Optical Instruments, Optical devices.
Le Vitrail; Son Histoire, Ses Manifestations à Travers les âges et les Peuples Ottin, L. 1896 Glass painting and staining
The Arcana of Arts and Sciences: or Farmers’ & Mechanics’ Manual: containing a great variety of valuable receipts and useful discoveries… Parker, M., Dr. 1824 Formulae, Recipes, Receipts, Agriculture, Industrial Arts, Pigments, Dyes, Dyeing, Woods, Metallurgy, Stains, Varnish, Glass manufacture, Cements, Enamelling
Curiosities of glass making: With details of the processes and productions of ancient and modern ornamental glass manufacture Pellatt, A. 1849 Glass manufacture, Anceint glassware, Technique
The glass collector; A Guide to Old English Glass Percival, M. 1919 Glassware
The amateur’s handbook of practical information for the workshop and the laboratory, 2nd Edn. Phin, J. 1879 Workshop, Laboratory, Recipes. and at
Glass, paints, oils and painters’ sundries Pittsburgh Plate Glass Company 1901 Trade Catalogue, Art materials, Glass, Ornamental
Glass, Paints, Varnishes and Brushes: their history, manufacture, and use Pittsburgh Plate Glass Company 1923 Glass, Glazing, Mirrors, Plate glass, Leaded glass, Store front, Commercial furniture, Pittsburgh Plate Glass Company
Old Beauty in New Glass Pittsburgh Plate Glass Company 1930 Trade catalogue, Glass, Ornamental glass, Windows, Art glass, Stained Glass
A treatise on the origin, progressive improvement, and present state of the manufacture of porcelain and glass Porter, G. R. 1832 Porcelain, Glass manufacture and similar at
The Rudiments of Mineralogy, 3rd Edn. Ramsay, A. 1885 Mineralogy, Rocks & Minerals
The Glass Sands of Kentucky: A Detailed Report Covering the Examination, Analysis and Industrial Evaluation of the Principal Glass Sand Deposits of the State Richardson, C. H. 1920 Rocks & Minerals, Sand, Glass manufacture
Glorious Glass at St. John’s Church, Gouda Rijksen, A. A. J. 1900 Sint Janskerk (Gouda, Netherlands), Glass painting and staining
Glass Manufacture Rosenhain, W. 1919 Glass manufacture
Vasily Kandinsky painting on glass (hinterglasmalerei) Anniversary Exhibition Rothel, H. K. 1966 Wassily Kandinsky, Glass painting and staining, Stadtische Galerie in Munich
Structure and Kinetics of Glass Corrosion [D.Phil Dissertation] Sanders, D. M. 1973 Glass, Glass corrosion
La Verrerie depuis les Temps les Plus Reculés Jusqu’à nos Jours

[See also 1869 edn]

Sauzay, A. 1868 Glass, Glassware, Glass manufacture, Glass craft, Decoration and ornament, Glass painting and staining, Mirrors, Optical glass, Optical instruments, Eyes, Artificial, Glass beads
La Verrerie depuis les Temps les Plus Reculés Jusqu’à nos Jours, 2nd Edn.

[See also 1868 edn]

Sauzay, A. 1869 Glass, Glassware, Glass manufacture, Glass craft, Decoration and ornament, Glass painting and staining, Mirrors, Optical glass, Optical instruments, Glass eyes, Glass beads, Pigments, Water colours, Cosmetics, Fabrics and dying,
Wonders of Glass‐Making in All Ages Sauzay, A. 1870 Glass manufacture, Glassware
Marvels of Glass‐Making in All Ages Sauzay, A. 1870 Glass, Glass manufacture
Handbook of the Glass Industry Scholes, S. R. 1941 Glass manufacture, Chemistry, Physics, Orton Cones, Recipes, Conversion tables, Commercial advertising
Recipes for Flint Glass Making: being leaves from the mixing book of several experts in the flint glass trade…, 2nd Edn. Scott, Greenwood & Son (Pub.) 1907 Glass, Workshop recipes
General Catalog 1911-1912

[Mostly wood-related]

Segelke & Kohlhaus Mfg. Co. 1912 Trade Catalogue, Wooden fittings, Wood windows, Commercial fixtures, Art glass, Stained Glass
The chemistry of the several natural and artificial heterogeneous compounds used in manufacturing porcelain, glass, and pottery

[Originally published 1837]

Shaw, S. 1900 Pottery, Chemistry, Technical
The Methods of Glass Blowing ‐ For the use of physical and chemical students Shenstone, W. A. 1897 Glass blowing and working
The Methods of Glass Blowing, and of Working Silica in the Oxy‐Gas Flame: For the use of chemical and physical students [see also 1916 edn’ Shenstone, W. A. 1902 Glass blowing and working
The Methods of Glass Blowing, and of Working Silica in the Oxy‐Gas Flame: For the use of chemical and physical students [see also 1902 edn’ Shenstone, W. A. 1916 Glass blowing and working
Stained glass tours in France Sherrill, C. H. 1908 Glass painting and staining, Church buildings, Cathedrals, France, Travel
Stained glass tours in England Sherrill, C. H. 1909 Glass painting and staining, Church buildings,Cathedrals, England, Travel
A stained glass tour in Italy Sherrill, C. H. 1913 Glass painting and staining
Photography in a nut shell; or, The experience of an artist in photography, on paper, glass and silver, with illustrations. Simons, M. P. 1858 Photography, Photographic chemistry, Daguerreotype, Ambrotype
The Laboratory, or, School of Arts: Containing a large collection of valuable of secrets, experiments, and manual operations in arts and manufactures… Vol II, 6th Edn.

[See also Vol I]

Smith, G. 1799 Industrial Arts, Technology, Receipts, Recipes, Coins, Medals, Drawing, Painting, Gnomonics, Optics, Etching, Engraving, Paint pigments, Varnish
The Laboratory, or, School of Arts: Containing a large collection of valuable of secrets, experiments, and manual operations in arts and manufactures… Vol I, 6th Edn.

[See also Vol II]

Smith, G. 1799 Industrial Arts, Technology, Receipts, Recipes, Fireworks, Metallurgy, Glass making, Glass staining and painting, Metal casting,
Practical instructions in enamel painting on glass, china, tiles, etc … Snell, H. J. 1874 Glass painting and staining, China painting, Enamel and enamelling, Artists’ materials
The golden cabinet : being the laboratory, or handmaid to the arts : containing such branches of useful knowledge, as nearly concerns all kinds of people, from the squire to the peasant, and will afford both profit and delight Spotswood, W. 1793 Chemistry, Technical, Industrial arts, Technical manuals, Formulas, Recipes, Gilding, Glass, Drawing, Dyes and dyeing, Japanning and similar at
Decoration of Metal, Wood, Glass, etc.: A book for manufacturers, mechanics, painters, decorators,… Standage, H. C. 1908 Workshop recipes, receipts, Metal, Glass
Old Irish glass Stannus, G. 1921 Glassware, Irish
Procedures In Experimental Physics Strong, J. 1938 Experimental Physics, Laboratory, Glass blowing, Optics, Heat, Radiation, Vacuum, Moulding and casting
A Treatise on the Art of Glass Painting Suffling, E. R. 1902 Glass painting and staining
Memorial windows Tiffany Glass & Decorating Co. 1896 Glass painting and staining, Favrile glass, Catalogues, Trade catalogues
Tiffany Favrile Glass, Tiffany Windows, Tiffany Mosaics, Tiffany Monuments, Tiffany Granite [see also later edition] Tiffany Studios 1913 Catalogues, Mosaics, Glass painting and staining, Memorials, Sepulchral monuments.
Tributes to honor, suggested types of memorials by the ecclesiastical department of the Tiffany Studios. Tiffany Studios 1918 Catalogues, Glass paining and staining, Sepulchral monuments.
Tiffany Favrile Glass, Tiffany Windows, Tiffany Mosaics, Tiffany Monuments, Tiffany Granite [see also earlier edition] Tiffany Studios 1922 Catalogues, Mosaics, Glass painting and staining, Memorials, Sepulchral monuments.
Art in Glass: A guide to the glass collections Toledo Museum of Art 1969 Glass art
Philological Studies in Ancient Glass

[1922 PhD Thesis]

Trowbridge, M. L. 1930 Greek language, Latin language, Classical literature, Glass Manufacture, Glass uses, Glass
On some Optical Peculiarities of Ancient Painted Glass, in Proceedings of the Clifton Antiquarian Club for 1884/88-1909/12, Vol 1, pp 207-216.

[Appears to be the same as the book of the same name]

Tuckett, F. F. 1888 Trademarks, Merchants
On some Optical Peculiarities of Ancient Painted Glass. Offprint from VClifton Antiquarian Club. Tuckett, F. F. 1888 Glass painting and staining, Medieval
Journal of the Society of Glass Technology, Vol IV Turner, W. E. S. (Ed) 1920 Journal, Technical, Glass Technology
Journal of the Society of Glass Technology, Vol V Turner, W. E. S. (Ed) 1921 Journal, Technical, Glass Technology
Journal of the Society of Glass Technology, Vol VI Turner, W. E. S. (Ed) 1922 Journal, Technical, Glass Technology
Journal of the Society of Glass Technology, Vol VII Turner, W. E. S. (Ed) 1923 Journal, Technical, Glass Technology
Chemical analysis for glassmakers: Containing methods of analysis for clays and other silicates which will be found useful for the pottery industry Uhlig, E. C. 1903 Glass manufacture, Chemical analysis,
The glass industry. Report on the cost of production of glass in the United States United States Bureau of Foreign and Domestic Commerce 1917 Glass manufacture, Industry, Glass industry
Information Concerning Optical Glass and Chemical Glassware United States Tariff Commission 1919 United States, Glassware, Glass manufacture, Optical glass, Trade Tariffs
Notice historique sur les Peintres-Verriers d’Anvers du XVe au XVIIIe Siècle van Cauwenberghs, C. 1891 Glass painting and staining
University of Illinois Engineering Experiment Station Bulletin No. 118, December 1920, Dissolved Gases in Glass Washburn, E. W., Footitt, F. F. and Bunting, E. N. 1920 Glass manufacture, Glass chemistry
Report on the Manufacture of Glass Weeks, J. D. 1883 Glass Manufacture, Glass-working, Glass composition, Report, Statistics, 1880 Census, United States,
Stained glass; a handbook on the art of stained and painted glass, its origin and development from the time of Charlemagne to its decadence (850-1650 A. D.) Werck, A. 1922 Glass painting and staining, Mediaeval, Art
Irish Glass: An account of glass‐making in Ireland from the XVIth century to the present day Westropp, M. S. D. 1920 Glass, Glass manufacture, Ireland
Stained glass work: a text-book for students and workers in glass.

[part of The Artistic Crafts Series of Technical Handbooks, ed. W. R. Lethaby]

[See also 1905 edition’

Whall, C. W. 1920 Glass painting and staining, Glass manufacture, Technique and similar at and at
Stained glass work: a text-book for students and workers in glass

[part of The Artistic Crafts Series of Technical Handbooks, ed. W. R. Lethaby]

[See also 1920 edition]

Whall, C.W. 1905 Glass painting and staining, Glass manufacture, Technique
A concise account of the principal works in stained glass that have been executed Willement, T. 1840 Glass painting and staining — Great Britain
William Morris & Compy (Ruskin House) Ltd William Morris & Co. 1910 Windows, Glazing, Glass, Stained Glass, Casement windows, ornamental metals, Trade Catalogue
Notes on the development of the ruby color in glass in University of Illinois Bulletin Vol XI No. 23, 30 July 1914 Williams, A. E. 1913 Glass, Glass chemistry, Ruby
An inquiry into the difference of style observable in ancient glass paintings: especially in England: With Hints on Glass Painting, Vol. 1

[See also Vol 2]

Winston, C. 1847 Glass painting and staining and similar at and at
An inquiry into the difference of style observable in ancient glass paintings, especially in England with hints on glass painting, Vol. 2

[See also Vol 1]

Winston, C. 1847 Glass painting and staining and similar at
Memoirs illustrative of the art of glass painting Winston, C. 1865 Glass painting and staining and similar at
One Thousand Valuable Secrets in the Elegant and Useful Arts, Collected from the Practice of the Best Artists, and … Woodward, W. W. 1795 Receipts, Recipies, Art materials, Cooking, Industrial Arts, Formulae, Engraving, Metallurgy, Varnish, Glass Manufacture, Glass painting,
The Manufacture of Optical Glass and of Optical Systems: A war-time problem Wright, F. E. 1921 Optical instruments, Optical glass, Glass manufacture
Manual of Laboratory Glass Blowing Wright, R. H. 1943 Glass Blowing, Technique
Collecting old glass: English and Irish Yoxall, J. H. 1916 Glass collecting, Glassware

Well that’s all folks. Happy reading!

Posted in Books | Tagged | Leave a comment

Thickening Glastac

Today I want to have a short chat about my experiences with Bullseye’s Glastac and some experiments with using CMC to thicken it. There’s no rocket science. I simply though you might enjoy another way to make use of your CMC.


If you’re a glass fuser you’ve probably used Glastac. If you haven’t I recommend you try it.

Glastac is a deliberately weak glue and in my experience it cleanly burns away in a kiln. It is useful because you can glue together the component parts of your glass masterpiece with the certain knowledge that you can re-place the parts for quite a long time. Better still, it helps to ensure your masterpiece will not fall apart when you are moving it to your kiln.

As an aside, I caution against using white PVA glues, such as the oft-recommended Elmer’s Glue. Although I do use PVA glues occasionally, I have noticed that it does not always cleanly burn away and that it can cause damage to a glass surface. I particularly notice this when an excess of PVA is used. But I digress.

The only problem I have found with Glastac, particularly when used in excess, is that surface tension sometimes drags small pieces of glass away from where I put them. Using less Glastac helps avoid this problem but the converse situation is that sparing use of Glastac means that the small pieces of glass are not sufficiently glued to stay put.

And then I noticed that Bullseye had introduced Glastac in a gel form. Hmm. Thinks. Can I find the Manufacturer’s Safety Data Sheet (MSDS) to find out how it differs from the “old fashioned” Glastac? No, so it’s time to just experiment.

Avid readers amongst you will remember that I’ve chattered about carboxymethylcellulose (CMC) on a number of occasions. Most of my chatterings were in Squirt Your Frits but I’ve also mentioned it in passing in other places such as converting ordinary safety flux into a gel form over at Make Your Own Safety Flux.

This made me wonder if a little CMC gloop would thicken “old fashioned” Glastac and make it even better.

Thickening Your Glastac

dscf3558-glastacInstructions on where to find CMC, what it is, how it works and how to make your own CMC gloop is covered in plenty of detail over in my Squirt Your Frits blog. I will not repeat all this information so read that blog and come back again if you need to. I will however show you pictures of a bottle of Glastac and (lower down) a little 100 gram pot of CMC sold under the “Tylo” brand name typically bought by sugar crafters.

Making your own substitute for Bullseye’s Glastac Gel is a simple matter of thickening up some “old fashioned” Glastac with CMC. However the devil is, as they say, in the detail.

I found it most convenient to start by making up some “sloppy” sol-phase CMC gel. The exact consistency does not matter. All you are aiming for is a CMC gel that is thick but flows reasonably slowly when you tip the container.

dscf3555-cmc-potNext, you need to find another little container and add some Glastac to some CMC gel and give it a thorough mixing. If the outcome is too thick, either add some more Glastac or add some water. If the outcome is too runny add some more CMC gel.

As to the exact proportions of Glastac and CMC gel I can only report that making numerous little batches with differing proportions didn’t make seem to make any noticeable difference. As long as there’s a reasonable amount of Glastac in the mixture it’s going to be a glue. As long as there’s some CMC gel in the mixture it’s going to be thicker.

What could be simpler than that?

Speedy Gel?

In an attempt to make the homemade substitute dry quicker I tried using propanol in place of some of the water.

There’s nothing special about propanol (also known as isopropyl alcohol). It’s just an industrial alcohol  that is widely used as a solvent and as such it’s also useful for cleaning glass. Having said that, I mostly use acetone for cleaning glass.

However, unlike the ethanol (also known as ethyl alcohol) in your booze, it’s not safe to drink. Here in the UK I buy it from APC Pure rather than from glass suppliers simply because it’s much cheaper and they’re relatively local. I’m not connected with APC Pure other than being a customer. And once again, I digress…

I didn’t notice any adverse effects of using this modified mixture other than the smell of evaporating propanol. I can’t really say that I noticed the glue drying noticeable quicker but to be fair I wasn’t conducting a proper controlled experiment against a stopwatch.

So, I leave you with the thought that using an alcohol, such as propanol, should quicken the rate at which the glue dries but no convincing practical evidence. This is a prompt for you to continue the experiment and tell me!

Homemade Glastac Gel In Use

Although I have not compared this homemade Glastac gel mixture with the genuine  Bullseye’s Glastac Gel I can at least tell you that I’ve had good results with the homemade substitute (with or without adding alcohol).

The homemade mixture still works as a weak glue. The improvement is that it no longer seems to cause little glass pieces to slide and shift as the glue dries. Other advantages are that it’s quick, easy and cheap to produce in small quantities and you don’t need to find more space for yet another bottle of glue.

If you find your homemade Glastac gel mixture works well you might consider buying some of the real Glastac Gel. At the worst it’s going to be no better. At best it’ll be even better.

Shelf Life

I found that leaving a small open pot of my homemade Glastac Gel substitute lying around for several weeks resulted in an “infection”. The feint tint of green near the surface leads me to suspect the beginnings of algal growth. Maybe I’ve discovered a new balanced diet for bugs. Hmm.

But all is not lost. Simply make up your homemade Glastac gel mixture in small quantities when you need some.

This does not mean you have to make up the CMC gel in small quantities. There is a shortcut. You may recall that I’ve already mentioned in Freeze Your Frits that your CMC gloop will freeze successfully. Store your excess in the freezer and make use of it a little at a time.


That’s all folks.

Posted in CMC, Experiment, Glastac, Tylo | Tagged , , , | Leave a comment

Shake Your Globs

If my early chattering about making globs from scraps of ordinary stained glass in Recycling Scraps of Stained Glass and with fusing glass at Waste Not Want Not have inspired you to make your own then maybe today’s blog will be of some interest. But only if you also do copper-foiled “Tiffany” style work.

Reducing waste and saving the planet is a good ethic, but what’s the point if you don’t make use of them?

I previously mentioned that kids enjoy collecting the recycled glass globs and that sometimes they can be used for pieces of jewellery too. Also, if you live in the land of deliberate bad spellers you might consider making jewelry with them instead.

Today’s theme is all about making use of recycled globs in your copper-foiled “Tiffany” style work.

Grind Before Foiling

Wrapping copper foil around a glob is a rather fiddly process. Not only is it a curved surface but it’s also rather smooth and slippery. The simple answer to this problem is to grind the edges of the globs so that you have a roughened surface against which the copper foil sticks more easily. Grinding can also be used to subtly re-shape a glob that has a defective or irregular shape.

Once you have wrapped the globs with copper foil you’ll want to burnish the copper foil and make the globs ready for soldering. Use your fingers to gently push-in the upper and lower edges of the copper foil but do not waste too much time on this. All that you need to achieve is a crinkly edge that needs the burnishing “finished off” by a method that is less fiddly and more efficient than using a fid or Allnova tool.

Burnishing the Foil

A simple and effective way to complete the burnishing process is to put your foiled globs into a jar with some un-foiled globs, put the lid on the jar, then shake until the burnishing process is complete. This trick is something I read on a forum years ago. So long ago that I don’t recall where or when. There’s no credit due to me for this burnishing method but I can at least recommend it.

dscf3492-globs-and-jarOn the right you’ll see a picture of a “half pound” jar, some un-foiled globs and some foiled globs. Notice the relative quantities being used. Notice that the foiled-globs still have crinkly edges to their copper foiling.

The number of un-foiled globs to use is not critical. It partly depends on the size of the jar just as it depends on how many foiled-globs are to be burnished. Too many globs in the jar means there’s not enough space for the globs to do their burnishing task. Too few globs in the jar means fewer impacts resulting in a slower burnishing process.

dscf3498-foiled-globsYou need to stop shaking as soon as the copper foil is burnished, otherwise the burnishing gets over-done and the copper foil starts to peel away from the globs. The picture on the right shows you the same foiled globs after burnishing. Good, eh?

This noisy task is enjoyed by children but do bear in mind that child labour (labor) is likely to result in over-shaken globs because they are more interested in the noise than the degree of burnishing. To mitigate this problem, reduce the number of un-foiled globs (or maybe eliminate them) so that the burnishing process is slower, thus extending their acceptable period of fun and enjoyment.

Using the Foiled Globs

You might think that there’s nothing more for me to say about how to use some copper-foiled glass. But you’d be wrong. If writing some more means there’s less time for housework then I’m not going to be deterred.

The privileges of childhood include the latitude to do stupid things like stuff small things up noses or in mouths. So, here’s an example of how I tend to use under-sized globs. Incidentally, it’s also a way by which I make use of the irregular shaped rectangles that we produce when squaring-off a wonky ends of newly purchased sheets of glass that were not accurately cut by the supplier.

dscf1719-glob-use-1In this picture you see a small area of a finished abstract piece of copper-foiled work, the design of which is motivated more by the use of scrap glass than intentional artistry. Of greater note in consequence of the theme of this posting is the use of foiled globs. Of incidental interest is the use aforementioned irregular-shaped strips of glass that tend to arise from “squaring-off”.

You can see that this particular example is not random. It may be a “sort-of rainbow” but in other pieces I arrange the globs such that they “sort-of flow” down through “sort-of cracks” between the irregular glass strips in the manner of “sort-of fractured rock”. Notice also that I’ve left a big hole (negative space) in the design. I also try to introduce excitement and interest by using different textures, differing opacity, slipping in a slice of agate or messing around with incomplete patination. Sometimes the best results come from not thinking too much!

dscf2414-glob-use-2My second example is what can be done when you have a huge excess of globs and can’t bear to throw them out. From the picture you’ll see one end of a “box of bubbles”. Just like the previous example I’m using both flat glass, foiled globs and leaving some holes. Incidentally, have you noticed that I chose a Wissmach hammered green border glass to reinforce the “blobby” nature of the interior of the panel?

There are two problems with this kind of panel. The first is that it can use up an awful lot of lead solder and the panels can get very heavy as a consequence. The second is that it’s very time consuming to make. So don’t make these panels too large and don’t expect to recover the real cost of making them if you intend to sell them!

My final comments relate to the technical matter of soldering thick globs into a panel made with thinner glass. You will no doubt realise that the sheet glass will be about 3mm thick but the globs might be 6mm. So, the globs will tend to “stick out” at the front.

If you want your globs to “stick out” only on the front of the panel then simply lay out the pieces front-side uppermost and get soldering without further ado. As an alternative you might try using thick card scraps underneath the plain glass pieces which then allows the globs to “sink” backwards into a more balanced and less proud form.

Concluding Remarks

So, there you have it. A couple more ways to save the planet by making use of recycled glass globs and a simple but effective way to burnish the copper foil onto globs.

A mercifully short blog and not one hint of maths or science. Aren’t you the lucky ones?!

Happy shaking and a happy (though belated) New Year.

Posted in Copper-foiled, Recycling | Tagged , | Leave a comment

Make Your Own Glassline Paper

Today’s chatter is for glass fusers and is about Glassline Paper. I’ll discuss how and why you might make your own, either because Glassline don’t produce exactly what you want or because you have the time and inclination to make a relatively inexpensive equivalent.

I don’t think I’ve inflicted mathematics onto you in previous blogs so now’s my chance. I hope to show you that mathematics (and the scientific method) can sometimes be useful, even when you’re not a mathematician or scientist.

Some Background

If you’re not familiar with Glassline products then a visit here will put you in the picture. Today we’re interested in the Glassline Paper and Glassline Pen products. I don’t often use them myself but there are times when they’re useful.

dscf3548-glassline-paper-examplesGlassline papers are available in a variety of colours, patterns, textures and sizes. Here’s a picture of a small selection of examples. You’ll find more examples at Glassline’s online shop here and summarised here in a single page. Both links contain information about how to use the Glassline papers.

As noted in those two links, Glassline Pens can be used to draw directly on Glassline Paper and I’ll come back to this little fact later when I talk about making your own papers. You can see a colour chart here and you will see the variety of standard colours is not large – but you can mix the colours if you wish.

Something worth mentioning for the benefit of novices is that Glassline Pens aren’t pens. They’re flattish bottles of coloured materials that can be fired and you can buy “stick-on” tips so that the bottles can be used as “squirty pens”. As is my habit, I refer you to the Manufacturer Safety Data Sheet (MSDS) page to find out what materials produce which colour and the all-important advice about how to safely use them. Potters amongst you will notice similarities with materials used in glazes.

dscf3554-glassline-pen-examplesThe picture opposite shows you a couple of example Glassline Pen bottles. Although you can also use a paint brush, an airbrush or whatever else takes your fancy, today we’re only interested in these Glassline Pens in one context – as the colourant for Glassline Papers.

Incidentally, Glassline only quote temperatures in Fahrenheit. For future reference, 1500°F is about 816°C and 1000°F is 538°C and you shouldn’t worry if you want to round off the numbers.

Now that you’re familiar with Glassline Pens and Glassline Papers, we’re ready to continue

An Accidental Discovery

It is quite some time since I discovered you can put Bullseye thinfire paper between layers of glass. I don’t think I ever remembered to mention this in past blogs so I now apologise and hint that this turns out to be part of what lies behind today’s discussion.

More recently I decided to buy a few Glassline Pens and a few small packs of Glassline Papers so that I could experiment with them. Until recently most of the packs of Glassline Paper remained unopened as I rarely find a use for them and have only spent a little time experimenting with them.

dscf3560-glassline-paper-logoOne of the packs of Glassline Paper I opened last week came with a surprise discovery. I noticed that the obverse (back) of the papers had the familiar logo and markings of Bullseye Thinfire paper. Previous papers did not have the Bullseye Thinfire markings. The picture opposite shows what I mean. Three sheets out of twelve identifying their origin doesn’t sound random to me so I was left wondering if Glassline didn’t intend to  reveal what their papers were made from. This is something we will test statistically in the next section.

A final realisation was that the Glassline Paper is coloured with what looks like and what feels like Glassline Pen colourants. This is hardly surprising when you remember that Glassline tell us that we can use Glassline Pens on Glassline Paper.

Mathematics is Fun

If the papers being used at the Glassline factory were unpacked and stacked randomly then we might expect half to be plain-side up and half plain-side down. If Glassline are trying to hide the fact that they use Bullseye Thinfire paper, in an attempt to obscure how their products are made, we’d expect Glassline to deliberately stack their Thinfire paper the same way so that the plain side ends up on the backs of their Glassline Paper, covering the Bullseye logo and markings with the colourants.

I have 12 sheets of Glassline Paper so would expect to see the Bullseye logo at the back of about 6 sheets if Glassline doesn’t care which way up they use the Thinfire paper. As already mentioned, I observed just 3 out of 12 having the logo on the back. If this is deliberate bias then it would be interesting to find out more and the Chi-squared test is how we find out.

For our statistical test we need to confirm (or reject) our “null hypothesis” that 3 out of 12 is statistically no different to 6 out of 12.

If that sounds daft to you, ask yourself these next two questions. Ask yourself “how many children of the same gender can a family have before we decide something weird has been happening” and ask yourself “how many times you can flip a coin and get the same result without getting worried that there’s something wrong with your coin”.

But I digress…

We start our Chi-squared test with some calculations based on observed (O) and expected (E) results. We have 12 samples, 3 of which have a logo on the back…

Paper Side         O         E          O-E     (O-E)2  (O-E)2/E

Back is plain      9          6          3          9          1.5

Back has logo   3          6          -3         9          1.5

We add up the two numbers at the right to get 3.0 and this is our Chi-squared value.

We now need to think about “degrees of freedom” because laying a sheet of paper (or flipping a coin) involves the freedom to do something that causes something to happen.

Should we decide to lay a sheet of Thinfire with the plain side upwards then we automatically know that the only other possibility is to have had the plain side downwards. Notice that we had two possible options and that choosing one of them automatically determines what the eliminated alternative was. So, two options gives us just one “degree of freedom” to choose. Therefore 1 is the degree of freedom we need for our Chi-squared test.

Looking at a Chi-squared table in the row for 1 degree of freedom we find 3.0 is a Chi-squared value that lies somewhere between the columns headed with 0.10 and 0.05. These two column headings are upper and lower bounds on the probability we’re looking for. These numbers can be represented in more familiar ways. Instead of 0.10 you could say 10% or 1 in 10. For 0.05 you could say 5% or 1 in 20.

Therefore, in human-speak, the 0.10 and 0.05 mean that 3 out of 12 sheets of Thinfire paper with their plain side upwards will happen somewhere between 10% and 5% of the time when we do our “sampling”. These are quite large probabilities which means our null hypothesis (that there is no difference) is probable. The corollary is that our original hypothesis is not probable. If our original hypothesis is not probable then Glassline aren’t trying to hide the fact they’re using Bullseye Thinfire paper and are therefore not actively using the Thinfire paper one way or the other.

Therefore, based on my small sample of 12 pieces of Glassline Paper, 3 out of 12 is no different than 6 out of 12. The same would apply to 9 out of 12.

If the whole concept of 3 out of 12, or 9 out of 12, being no different than 6 out of 12 has your intrigued or stunned, I challenge you to analyse some of the statistics behind advertising claims you’ll see on TV or the statistics being quoted by governments or other official bodies. Often you’ll discover the claims are being made on the basis of customer preferences, responses or equivalent measures that are not statistically valid. Knowledge is power.

If all that babble left you realising you’ve forgotten all your mathematics then here is where you can revise your Chi-squared test. It’s also where you can find a Chi-squared value table.

Making Your Own

And at long last we come to the most important part of my chatter – telling you what Glassline Paper is made of and how you might make your own equivalent papers.

All you need to make your own is Bullseye Thinfire paper, some Glassline Pens and a method of production.

There are many methods by which you can apply the colour to the papers. Some of them are mentioned by Glassline. You might use a paintbrush, sponge pad, an airbrush or whatever else comes to mind. Sometimes you may wish to add water to make a thinner mixture, especially when you want to use an airbrush or want to produce a paler tint.

Remember also that Glassline tell us that we can use Glassline Pens to decorate their Glassline Papers.

dscf3561-glassline-overspillAlthough Glassline Paper tends to have colouring on one side, you will notice in the picture opposite that some papers have overspill on the reverse side.  I don’t suppose Glassline care about this overspill beyond recognising it means they’re using more colourant than they’d like to. For us, it means we have to buy papers that are neither single-sided nor double-sided. But bluntly, the backs are an untidy mess. I don’t like mess and it detracts from the quality of what we try to achieve with out work.

dscf3551-glassline-heart-2dscf3551-glassline-heart-1In these two pictures, on the left and right, you can see that it is possible to have one colour on one side and a different colour on the reverse. It may be a shabby example with sparse artistic merit but it does show us that there is no colour bleed from one side to the other other than my messy experimental workmanship.

dscf3549-glassline-paper-diyThe picture you now see offers a few examples that show we’re not limited to what Glassline have in their Glassline Paper product range. The grey-looking rectangle will fire to double-sided black. The narrow strip at the top has different colours on each side. The two examples on the right are single-sided and have two colours. The remaining example at the lower left is a single colour of brushed stippling.

And finally, do remember that when the thinfire paper has been fired, the Bullseye logo and associated markings will disappear.

I think you get the idea and hope these example inspire you to do your own experiments.

Thinking About Economics

It is worth considering the relative costs of buying ready-made Glassline Paper against making our own. What follows is a quick analysis that in turn will lead to some simple conclusions. If you’ve had your fill of mathematics then just skim read this section!

To begin with we need to know how much it costs to buy ready-made Glassline Paper. For those of you in the USA I offer you the Suede Glassline 5″x5″ Stone Paper kit as an example. For this product three sheets of 5 x 5inch costs $15.45. This equates to about $0.0319 per square cm.

By contrast, in the UK we might expect to pay £8.91 or thereabouts for a mix of 15 sheets of 6.5 x 6.5cm at Warm Glass UK. This is a similar quantity and equates to about £0.01406 per square cm.

We now need to compare this with the costs to make your own version of Glassline Paper.

Bullseye Thinfire paper costs vary depending on how much you buy and where you buy it. For the purposes of our calculations let’s take £19.47 for 10 sheets of 52x52cm quoted by Warm Glass UK. This turns out to be about £0.000720 per square cm. With modest bulk buying the cost of the Thinfire paper turns out to be a negligible cost when heading down the DIY route.

Glassline Pens cost around £7.25 or thereabouts from Warm Glass UK when bought in 2 ounce bottles. That’s about 56 grams for those of you who stopped using Avoirdupois units decades ago. Translating this mass into how much gets used per square centimetre is rather tricky as it depends on what we’re doing and how much water is in the mixture. A light wash of colour is going to use a lot less than a thick coating. All we know is that the colourant is costing us £0.1286 per gram used.

Let’s look at the problem in a different way instead. If we can limit our use of the Glassline colourant to less than £0.01334 per square centimetre we’re on a winning streak if we’re out to save money. We know this because we have calculated how much the finished Glassline Paper and raw Bullseye Thinfire papers cost per square centimetre.

But how much can we squirt out of a Glassline Pen before it costs us £0.01334? A quick calculation tells us it will be about 0.1037 grams per square centimetre. A tenth of a gram is a tiny amount, nothing more than a blob on the end of a skinny wooden coffee stirrer. However, even a tenth of a gram is enough to cover a couple of square centimetres of Bullseye thinfire paper with a heavy application and considerably more for a light coating.

But let’s not forget that we’re likely to find ourselves with mucky paintbrushes, palettes, airbrush equipment or whatever else we’ve been using as tools. Some of what was in our Glassline Pen will go down the drain as waste. Waste costs money too.

Practical Conclusions

If you have painterly skills then making your own versions of Glassline Papers is a viable proposition in many situations. Sometimes the cost to buy ready-made outweighs the time and effort needed to produce your own equivalent versions. Sometimes the uniqueness of what you make makes simple cost comparisons pointless. It’s a matter of judgement.

A generally applicable comment is to buy cheaply and minimise waste. This is common sense, but a failure to do this can negate your attempts to save money if that’s what you’re aiming for.

Heavy coatings of colourant laid on Bullseye Thinfire paper ought to be a financially viable alternative to buying ready-made Glassline papers but three factors should be borne in mind. If the thinfire paper is being purchased expensively in small quantities and if the results of the DIY activity result in a lot of waste colourant it is easily possible to make papers that are more expensive than could be purchased ready-made. Also realise that the time you take to make such papers adds to their cost.

In extreme contrast to heavy coatings, an airbrush can be used to disperse small quantities of watered-down colourant over a large area as speckles. This method ought to be the least costly because it uses the least quantity of colourant. Do remember that airbrushing speckles will only be financially viable if you already own an airbrush.

Related to speckled effects would be brushed effects, drawn effects or sponged effects, especially when watered-down colourants are being used. Again we should expect relatively low costs that are viable compared to ready-made papers.

Some of the Glassline papers will be harder to replicate and will use a lot of colourant. Examples of the crinkled, granite and sandstone papers where Glassline use two colours and/or the thinfire paper that has been “crumpled” and flattened-out before applying the colourants. Unless there is a compelling reason to make your own I reckon it’s not worth the trouble to make these at yourself, other than as experiments for the learning experience. Not only will it be a time-consuming task but the amount of colourant and waste colourant are likely to make it more expensive than ready-made papers.

A final conclusion is that we now realise that Glassline papers with overspill on their backs can be “finished off” to make them double-sided rather than “single-sided with mess on the back”. It may not matter to Glassline, but I try to consider how things look from the back of what I make.

In the final analysis, the most compelling case for producing your own papers is when you want to colour both sides of the thinfire paper and when you require colours or patterning that can not be obtained ready-made from Glassline.

Posted in Experiment, Glassline Paper, Glassline Pen, Inclusions, Money-saving ideas | Tagged , , , , , , , | 4 Comments

Secrets of the Microwave Kiln

I’ve just bought my third Hot Pot Maxi microwave kiln. But, why buy yet another “toy” kiln when I already have a “proper” glass kiln of a distinctly robust and modern design?

I hope to answer that question by talking about the distinctive nature of firing glass in a microwave kiln, a little about the economics of using them, and a little about how they work and how they deteriorate.

I think I need to do all of this because I don’t see anyone else talking much about it.

Experiences With a Microwave Kiln

I still use a microwave kiln because I can melt a small arrangement of glass and have it back out and in my hands, fused and shiny, within about two hours. My “proper” kiln makes me wait a whole day (and night). So, speed and convenience is one reason.

The barely-controllable ferocious heating in a microwave kiln results in a greater risk of glass cracking at it heats up and the lack of processing temperature control means it’s not uncommon to find a mutant distorted blob of glass is the unexpected result of a firing. And of course the small firing chamber means we don’t get to make anything larger than a brooch or pendant. Sometimes this is not a problem.

The down-side of the almost uncontrollable heating, as I’ve just mentioned, is that the shape and form of the resulting glass masterpiece is rather unpredictable. This becomes a particular problem when the microwave kiln gets older and heats less evenly. I’ll be coming back to the “getting older” aspect of microwave kilns later as it seems to be a widely neglected topic!

Another characteristic of microwave kilns is the incredibly rapid cooling inside the microwave kiln. It has scant regard for “proper annealing”. You might think that this must lead to problems but in truth it very rarely does.

We are repeatedly told that it is important to properly anneal our work. From this we might suppose that the rapid cooling in a microwave kiln without “proper annealing” might cause us significant problems. In truth I find that breakages caused by poor annealing are very rare. If this is a surprise to you then consider the size of items being produced and realise there’s only so much stress and strain that can be built up and “stored” in such a small piece of glass. This is particularly the case for simple shapes like a blob of glass, a little decorated tile or a simple pendant – in other words, exactly the kinds of things that you’d use a microwave kiln for.

You can, of course, pop your microwave kiln masterpieces into a “proper” kiln to “properly anneal” them though we can take paranoia too far sometimes.

Another aspect of the rapid heating and cooling in a microwave kiln that I have not seen mentioned anywhere relates to devitrification. With a microwave kiln the processing time is so short that glass that is susceptible to devitrification rarely has time to devitrify. A practical consequence is that I am able to reliably produce recycle my otherwise unusable scraps of “ordinary” non-fusing glass into blobs with little risk of devitrification. You can see real examples in my Recycling Scraps of Stained Glass blog and you should bear in mind that every single glob you see in the picture is not fusing glass. For the lazy amongst you, and because it’s colourful, I’ll re-post the picture from that blog:

DSCF1857 Recycled Glass Globs

And here’s and interesting example that proves the opposite situation from my last blog. This little wonderous spiky blob of glass devitrified before it melted completely:

DSCF3010 Spiky Devit

The big surprise is that my “proper” kiln fails to produce shiny globs with “ordinary” non-fusing glass. Devitrification is always a problem. Processing time is important when dealing with glass that was not designed to be re-fired.

In other experiments, using a “proper” kiln, I find that most kinds of “ordinary” non-fusing glass can barely cope with slumping without devitrifying at least to some degree. Someday I’ll do a blog about this but I’ve not finished messing about yet!

Reasons to Use a Microwave Kiln

A consequence of the foregoing chatter is that I continue to use a microwave kiln in four very particular situations:

  1. I can quickly and cheaply perform a simple glass-related experiment in a microwave kiln. Firing-up a big kiln and wait a whole day to find out what happened can be too long to wait sometimes.
  2. Children visiting for a “smashing time” can arrive in the morning to make something small and simple in a microwave kiln then take it home that same afternoon. While they wait for the microwave kiln too cool down they can also make something bigger and more “special” that later will go into the big kiln. Immediacy is important for kids, as is the excitement of seeing seething red-hot glass when they “peek”.
  3. I can recycle scraps of non-fusing glass into blobs without devitrification problems and in turn it means I throw very little waste glass away.
  4. I can quickly make small quantities of frit balls (and other similar little things) when I run out of them which means I don’t have to suspend my project work for a long time. That they’re badly annealed doesn’t matter here because they will be fired again!

You may be surprised to learn that point (3) is what my microwave kiln gets used for most of the time. Let me explain…

No matter how hard we try to make use of smaller pieces of glass we end up with small scraps that are unusable. Where possible unusable scraps get melted into globs. It makes environmental sense through I doubt the time and effort to make them is commercially viable.

Some of the smaller globs (under 6 grams) I use in my own copper-foiled work or give away to other crafters when we meet at events. They might end up as a glass highlight in a wooden decoration for example.

Larger globs (typically 6-10 grams) are supposed to be sold though I tend to give away most of them. My rule is simple – kids who show an interest in my work can have one free but horrible kids have to pay for them. There has to be a reward for being “nice”.

Microwave Kilns Deteriorate

I’ve already mentioned that I’m now on my third Hot Pot Maxi microwave kiln. What happened to the other two?

As battered and bruised old-timers the old microwave kilns have been retired. They now live in landfill. The blunt truth is that they’re fragile, get damaged easily and really do get old and tired.

I should now explain how a microwave kiln works (in brief) and then pull-in information to explain how and why they deteriorate and get old.

The body of a microwave kiln is made of a light and brittle ceramic material. Considering how light and thin the ceramic material is, it performs remarkably well as a thermal insulator.

With a new microwave kiln we can expect the grey heating material to heat up reasonably evenly. The relatively small degree of uneven heating will be caused by subtle differences in the mixture of materials and their thickness. With time the degree of uneven heating gets worse for reasons that follow…

Repetitive heating and cooling causes repetitive expansion and contraction which will result in hairline cracks. The brittle nature of the ceramic material (and the inside coating) of a microwave kiln means it starts rather soon and gets progressively worse the more you use the microwave kiln.

Exactly where the hairline cracks appear depends on the unavoidable “defects” of manufacture and some basic physics. That the cracks always seem to run from top to bottom is purely down to the combination of geometry and coefficients of expansion – the inside gets hottest so wants to expand proportionately more than the outside. The reverse happens when cooling. This difference causes stresses and strains which result in hairline cracks appearing. So, don’t be unduly concerned by hairline cracks because they’re a natural consequence of the heating and cooling and the materials being used.

We now need to remember some high school physics. Do you remember that heat can be transferred by any combination of conduction, convection or radiation?

The hairline cracks will cause uneven heating because areas that heat up fastest can not conduct some of their heat to cooler areas because of the barrier caused by the cracks. So, any minor differences in one area heating up faster than another due to original manufacturing “defects” is made more pronounced when hairline cracks come into play. As the size of the firing chamber is so small we can assume there is no heat transfer by convection. There will however be some heat transfer by radiation because that’s what we’re using to heat up the glass in the firing chamber.

So, uneven heating becomes an unavoidable and noticeable problem once the microwave kiln starts to develop hairline cracks. This in turn adds to the unpredictability of what you can produce in a microwave kiln. A partial answer to this uneven heating is to pause the firing mid-way, have a peek, rotate the lid by half a turn, then continue to the firing. With practise and good timing this can almost negate the effects of uneven heating.

Glass slippage is another problem because. It is very easy to accidentally nudge the lid of the microwave kiln and cause the glass pieces inside to slip. A microwave oven platen that rotates badly (wobbling or shuddering) can also cause glass to slip. Heating too rapidly may cause glass to crack and move, so is another form of slipping. Any of these (and other) mishaps may result in hot glass “gluing” itself onto the base or the sides of the microwave kiln. You can also achieve the same effect by over-cooking the glass such that it becomes very fluid and “runs” to the side of the kiln to glue the top and base together.  Yes folks, I confess. I’ve experienced all these mishaps.

The trouble with glass fused onto the ceramic material is that you will find yourself gouging a big hole into the base or sides of the microwave kiln in your attempt to remove the glass. It is rarely possible to remove the glass without damaging the ceramic material, even if you have use kiln wash to protect the kiln base. Such mishaps tend to shorten the life of a microwave kiln, either because you find yourself with a kiln base that resembles the aftermath of World War I trench warfare, or sides where big chunks of the grey heating material are missing.

Using kiln wash and fibre paper can help deal with some of the problems some of the time but in my experience they will only reduce the rate of kiln destruction!

Another aspect of the deterioration relates to the heating ability of the dull grey gritty substance on the inner surface of the microwave kiln’s lid. It’s the heating element. The dull grey gritty substance is something I’ll talk about in more detail at the end of this blog so for the moment just accept that it is chosen for its ability to absorb microwave energy and re-emit that energy as heat. In other words, a microwave kiln works because of a peculiar characteristic of the grey material.

I am not sure why, but the effectiveness of the grey “heating” material seem to deteriorate over time, partly because of minor mechanical defects such as hairline cracks, but also because it seems to take longer and longer to heat up as the kiln is used more and more. This is something I noticed with my first microwave kiln but I hadn’t been keeping any records.

The fact it takes longer and longer for the microwave kiln to heat up with age implies there is some form of chemical deterioration in the “heating element” part of the microwave kiln. Anything that’s hot and in air tends to get oxidised as a matter of routine. This is perhaps most familiar to you if you’ve ever put some lovely salmon-pink shiny copper elements in your kiln-fired work and was disappointed to discover they came our red, purple or even black as heat and oxygen progressively turned the copper to copper oxide. This is what heat and oxygen routinely do to most things around us. This is what I suspect is happening to the “grey stuff” in the microwave kiln. But I suspect there are two other possibilties.

One of the alternative possibilities is that metals in coloured glass are “firing off” and reacting with the heating element. The other possibility is that the mixture of materials in the heating element react with each other causing chemical changes.

Whatever the cause, the effect is that the heating element becomes less susceptible to microwave energy so is not able to re-emit heat so effectively.

Firing History

My first microwave kiln told me that there was deterioration. So, for my second microwave kiln, I kept a record of each firing. Not much more than the date, what kind of task and how long it was “cooked” in the microwave. What you see in the graph below is the result of my nerdy record-keeping. Have a look at the graph then I’ll explain what it all means.


The graph shows that my second microwave kiln didn’t quite make it to 300 firings before I felt it was time to throw it away. The exact number of times was 283.

You can also see from the graph that the jagged curve runs from the lower left (the first few firings) to the upper right (the end-of-life firings). Notice also that the curve is steeply upwards on the left and goes shallow on the right. This curve tells us that a new microwave kiln is much quicker than an old one and that the super-duper performance of a new microwave kiln doesn’t last long.

Notice that I’ve scaled the processing time so that 100% represents how quick the new kiln was. This means that when I threw it away it was taking almost twice as long to do exactly the same job – over 180% of the original firing times. Notice also that the graph shows us that the rate of deterioration slows down and seems to be levelling out at around 180%.

There are consequences for this “deterioration”. One is that it takes more time and energy with an older microwave kiln when compared to a new one. The other is that there’s no point in relying on detailed accurate firing records with a microwave kiln because its behaviour changes over time.

I’ll now reinforce that last paragraph in a different way. If you use a firing time from an old microwave kiln to guide to what you should do with a new microwave kiln you will likely “double blast” your glass. It will be “double processed” and you may end up producing an very runny pool of molten glass. And runny molten glass flows rather well if a surface is not exactly level. This is how I managed to “glue” the inside of the lid of a microwave kiln onto its base using molten glass. Don’t be as stupid as I can be. Consider yourself warned!

Now that we have some evidence about how microwave kilns deteriorate, and why, lets look at the economics of using a microwave kiln.

Microwave Kiln Running Costs

There are different brands of microwave kiln and some brands come in different sizes. The kind I’m using has a firing chamber that is about 10cm in diameter and cost about 50 GBP. Knowing that your 50 pound investment will deteriorate and may be ready for landfill after about 250-300 firings is something to think about. So is the ever increasing cost of the electricity, the kiln wash, fibre paper, currency exchange rates etc.

So, how much does it really cost to fire-up a microwave kiln? Lets find out…

I’ve already mentioned 50 pounds Sterling (notice it’s “Pounds Sterling”, not “English Pounds”) as the purchase price of my new microwave kiln and that I got 283 firings out of my second microwave kiln. So, that’s about 17.6 pence per firing due to the kiln cost.

But electricity also costs money. I am using an old 650W microwave oven. The 650W measure is the microwave output, not the electricity consumed. From the technical information at the back of the microwave’s manual I see it consumes 1.1kW per hour. So that’s about 60% efficient. My electricity costs around 16 pence per kWh and I’ve factored-in a proportion of the standing charge. We end up with just a few pence of electricity per firing which I can now plot on a graph.


I see that the cost starts somewhere between 3 or 4 pence, quickly rises to nearly 5 pence, then slowly drifts upwards to a little over 6 pence per firing. If you compare this graph with the previous one you’ll see exactly the same shape but a different Y-axis scale. This is because we’re doing nothing more complicated by converting a Y-axis in units of time into units of pence by multiplying by a constant value. For full marks in a mathematics exam I should have perhaps chosen a Y-axis starting at 3p rather than zero to make better use of the space.

Other Running Costs

There are other running costs that were not included in the previous graph. We tend to use some kiln wash to protect the base of the microwave kiln. A tiny fraction of a penny per firing for kiln wash is negligible compared to the cost of your time and the other costs associated with running a microwave kiln.

You, like me, might also use Bullseye’s thinfire paper between the glass and the kiln surface. It’s expensive and it can’t usually be used more than once. But how expensive is it?

If you’re lazy you’ll buy ready-cut 10cm squares at around 11 pence per firing, such as from here at Glass Studio Supplies in the UK but if you compare the price for buying 100 big sheets, such as from here from Warm Glass in the UK, you find you could instead be paying around 6 pence for the same amount of thinfire paper. All it takes is the will to buy in bulk, a pair of scissors and a few minutes of your time.

And finally, we need to remember to allocate a portion of the cost of buying the microwave kiln to each firing as well as the electricity cost, both of which were calculated in the previous section.

Overall Running Costs

My second microwave kiln tells me to expect a lifetime of about 250-300 firings, or maybe more if I treat the microwave kiln with more respect and care. As most of my use of a microwave kiln is to produce circular blobs of glass, we’re talking “full-fuse-plus”. We might therefore reasonably expect a longer life for the kiln with profile fused work.

Record-keeping may be boring and nerdy but it clearly has its uses. I now know the lifespan for my second microwave kiln and how it has behaved from new until the time I threw it away. Combining all the information at current (2016) UK prices tells me that the total per firing will be somewhere in the region of 25 to 35 pence, depending on how old the microwave kiln is, the kind of work being done, and whether or not I am prepared to buy raw materials in bulk.

You might like to think about how costly it is to fire-up your “big kiln”. The same ideas and methods apply, but the numbers will be bigger.

How Microwave Kilns Work

If you’ve got this far and have an urge to find out more about how microwave kilns work, and would also like to know how you can make your own, you’re in luck. I’ve gathered together a few links below which I’ll pad out with some commentary.

When you hunt around the Internet you’ll maybe find some misleading information about “the grey stuff” in a microwave kiln. The grey material is not granite, nor is it graphite. It is a mixture of silicon carbide and sodium silicate. Notice I say silicon and not silicone. Silicon is a shiny silvery metal. Silicone is a kind of plastic used for waterproofing products, breast implants and more besides. Silicon and silicone are not the same things.

You will be familiar with silicon carbide as an abrasive if you’ve ever tumbled rocks and minerals. You will also be familiar with sodium silicate though it’s unlikely that you realise it. Both are inexpensive chemicals that you can buy on eBay and I’ll give you a couple of links later that tell you more about both of them.

Once upon a time I found a reference to both these materials when I was reading something about LVR Products’ Micro-Kiln EZ-5 and Micro-Kiln No 9. I made a note that in their parts list it said there was a ‘Repair Solution Set’ which consisted of Silicon carbide (solution A), Sodium silicate (solution B) and a Brush. I forgot to make a note of the URL and I can’t find with Google any more, so I’m sorry I can’t give you a link to this evidence. But not to worry. I have more sources of information that should reassure you I’m not talking out of my backside.

Silicon carbide is used as the heating element because it has the interesting property of absorbing microwaves and re-emitting the energy as heat. You can find out more about this grey “heating” chemical at Wikipedia’s entry for Silicon Carbide (especially in the Heating Elements section). You will also find silicon carbide mentioned in some of the links listed below.

To “glue” the silicon carbide to the microwave kiln lid requires a binding agent and although there are several possibilities, you will you find that the commercial repair kits seem to use sodium silicate. Find out more about this “binding” chemical at Wikipedia under Sodium Silicate (especially in the Refactory Use section).

Over at Paragon you will see repair instruction that mention a silicon carbide layer. Actually, this is a very useful little instruction manual for any microwave kiln user, not just the Paragon MagicFuse microwave kiln.

You can get a really good insight into how microwave kilns are made by watching a YouTube video called How to make a microwave kiln (Furnace) from scratch for £5. The audio is not good but it is worth the struggle. Not only will you see a microwave kiln being made but you discover silicon carbide is just one of many “susceptor” chemicals that can be used as a heating product and that there are different binders, not just sodium silicate. Also interesting in the narrative is an explanation of how the same heating method is used to cook microwave chips.

You can find out more information about microwave absorbers here though in a completely different context.

If this isn’t enough for you then there is an old technical reference about “self heating” ceramic crucibles for microwave melting of metals and nuclear waste glass  at the Office of Scientific and Technology Information in the USA which is not as irrelevant as you might initially suspect. Vitrification has for many years been considered as a “safe” method of disposal for nuclear waste materials.

For the fearless amongst you, I have found some rather technical references. I can promise you an especially dreary read with this patent. If it is too much for you, I suggest try the readable article here because they’re both about the same thing.

Are We Being Ripped-Off?

And finally, we should give some thought to whether microwave kilns are good value or not.  The same applies to repair kits that you might encounter.

For almost the cost of buying a replacement microwave kiln you can buy a microwave kiln repair kit. One example is here. I am always suspicious of spare parts and repair kits that cost almost as much as the original item.

If you have a look in eBay (or elsewhere) you’ll discover just how cheap silicon carbide and sodium silicate really are. This should make you wonder why there’s such a big difference between the price of these raw materials and the price of a commercial kit or a microwave kiln.

If you understand the instruction in the YouTube video I mentioned in the previous section you’ll begin to understand that 50 GBP is ten times the cost of making your own. Again, this should make you wonder why there’s such a big difference between the price of the raw materials and the price of a commercial microwave kiln.

Yes folks. Information is power. The power to exploit. And now you know their secrets they can’t exploit you so easily. But you can exploit what you know. You too can make a microwave kiln. You too can buy the materials you need to make your own repair kit.

If you enjoy making things and you don’t have a microwave kiln then making one is surely a candidate for the top of your “Things to Make” list.

Bye for now. Tomorrow I’m going to make some rainbows. How about you?

Posted in Devitrification, kiln schedule, Melting Glass, Microwave kiln, temperature curve | Tagged , , , , , , | 16 Comments