Glass Painting & Firing Questions

[Sashaziv]

Hi, great forum, I’ve found a lot of useful info! I’m learning stained glass painting here in Germany at the moment, mostly under my own steam as there aren’t many courses! I’m using Reusche weather resistant paints. I have some questions, which I couldnt find answers to. I’d really appreciate it any of you have some ideas. Apologies for the length of this!

1) Backpainting: I’m interested in firing glass with water-based gum arabic matting on both sides at 675C, with the glass resting on whiting on cordite boards. I’m wondering, will the backpainting actually fire properly though? Or is there a risk that it may remain partially opaque and be less glossy? Has anyone tried this, and what sort of results do you get?

2) Whiting. Do you have tips on how to get the whiting smooth, and how thick to put it down? On a recent attempt firing painted float glass, I tried the Elkus newspaper flattening technique. The whiting was Champagne chalk, I found it very difficult to get it perfectly smooth. And the glass did pick up some of the whiting texture, as well as partially clouding on the back side. Admittedly I didnt pre-dry the whiting out - could this be the decisive factor? Also, do you have an experience that one chalk type works better (e.g. Champagne, Bologna etc)? And does anyone use a whiting/ plaster of paris mix as per the Reyntiens book?

3) Paint consistency. I’m trying water-based gum arabic tracing, with water only, and with vinegar. I’m doing very detailed work, i.e. using the smallest water-colour brushes. I’ve found that the paint usually has to be diluted a fair bit to get the right viscosity. So I’m often reworking lines, in 2 or 3 layers, to get the right tone. According to the books this may not fire well! But I found the paint impossibly thick otherwise for fine delicate lines. (NB I prefer the quality of brush work to steel pen) I’m wondering, is this normal for miniature brush work. Or may something be wrong in my paint mixing?

4) I seem to remember reading somewhere that applying certain oils over matting/ tracing can reduce tonal loss in the kiln. Does this actually work, and if so, how do you do it?

Many thanks

Sasha

[Don Burt]

Hi, great forum, I’ve found a lot of useful info! I’m learning stained glass painting here in Germany at the moment, mostly under my own steam as there aren’t many courses! I’m using Reusche weather resistant paints. I have some questions, which I couldnt find answers to. I’d really appreciate it any of you have some ideas. Apologies for the length of this!

1) Backpainting: I’m interested in firing glass with water-based gum arabic matting on both sides at 675C, with the glass resting on whiting on cordite boards. I’m wondering, will the backpainting actually fire properly though? Or is there a risk that it may remain partially opaque and be less glossy? Has anyone tried this, and what sort of results do you get?

Firing with paint down is a calculated risk. I do it, but not unfired paint on both sides. Usually high-fire paint on the down side already fired, and low fire paint on the top side of subsequent firings. But whatever you want to do, it would be easy enough to test and see if you like it. I'd guess it will pick up some whiting and be duller, but maybe that's OK. Nobody will come to your door and protest that you're exercising poor form.

2) Whiting. Do you have tips on how to get the whiting smooth, and how thick to put it down? On a recent attempt firing painted float glass, I tried the Elkus newspaper flattening technique. The whiting was Champagne chalk, I found it very difficult to get it perfectly smooth. And the glass did pick up some of the whiting texture, as well as partially clouding on the back side. Admittedly I didnt pre-dry the whiting out - could this be the decisive factor? Also, do you have an experience that one chalk type works better (e.g. Champagne, Bologna etc)? And does anyone use a whiting/ plaster of paris mix as per the Reyntiens book?

675C shouldn't impart a whiting texture to float glass. Are you firing very slowly with a hold? I use newspaper on whiting or alumina and its smooth enough. I fire to 682 in my propane kiln very quickly with no hold.


3) Paint consistency. I’m trying water-based gum arabic tracing, with water only, and with vinegar. I’m doing very detailed work, i.e. using the smallest water-colour brushes. I’ve found that the paint usually has to be diluted a fair bit to get the right viscosity. So I’m often reworking lines, in 2 or 3 layers, to get the right tone. According to the books this may not fire well! But I found the paint impossibly thick otherwise for fine delicate lines. (NB I prefer the quality of brush work to steel pen) I’m wondering, is this normal for miniature brush work. Or may something be wrong in my paint mixing?

Little brushes are useless for line tracing. You would instead use a proper tracing brush. But the Elskus book told you that already. A number 3 tracing brush can make the thinnest of lines with its very tip. Tracing brushes come to a sharp point and hold enough paint to allow it to flow. You can get very detailed with it. I know its easier for me to say than to do. But I believe it. I do struggle with it myself. I'm OK with water/gum Arabic, but I recently started using Water Friendly Medium ( a cellulose ether product), and was really failing in my cold basement studio to get paint to flow off the brush. But it can be done. Best advice I got from my teacher was to slow down the brush stroke. Hold the brush upright like Elskus emphasizes. And keep trying to get the perfect paint consistency for opaque flow.

But lose the little brushes. Part of it is attitude. You kind of have to want to learn to do it. If you're German, well, you have no excuse but to learn to do it properly. To do otherwise would be to embarrass your heritage.

4) I seem to remember reading somewhere that applying certain oils over matting/ tracing can reduce tonal loss in the kiln. Does this actually work, and if so, how do you do it?

Don't know anything about that.

Many thanks

Sasha

[Sashaziv]

Hi, many thanks for your help Don, really appreciate it!

Re the backpainting, if I understand you correctly, then firing with both sides painted and unfired is not a typical practise, it being more reliable to fire each side seperately? And, when you say that firing with paint down is a calculated risk, what actually are the risks? Is this only the picking up whiting/ getting duller as you mention, or something even worse?!!

I’m afraid I dont quite understand your firing procedure. Are you saying that side that the back painting is fired first face up at a higher temperature, then the glass is turned over for the next firings, where the front painting is fired at lower temperatures? I’m going to be using an electric glass kiln, and wondering what high or low temps might be for my Reusche paints designed for 675C. Unless I’ve really misunderstood, that is!!

Re the whiting, this was an initial test using an electric ceramics kiln. It went at 200C per hour to 660C with a 5 minute soak, then I turned the oven off, and open the vents, as it doesn’t have a programmable cool down. I’m wondering if maybe I put the whiting on too thick. It was picking up all the creases in the newspaper. I will switch to a dedicated glass kiln for the next attempt.

Re the brushes and consistency, thanks for the tips on handling. I think maybe I phrased myself badly. I guess I meant sable rather than simply watercolour brushes, I do in fact also use a larger sable rigger type tracer too, which as you say does deliver a minute line if handled well, which ocassionaly happens in my case!! I do a lot of thinner, lighter lines. I’m trying to get the right consistency, but with only books to go on, its well, quite a bit of guessing/interpretation too as to what that might be! So I often wonder if my paint mix is too dilute. I suppose the proof is in the kiln! As you say, the best thing is to do tests.

I guess I’m aiming for variety of opacity, as sort of painterly approach. So this involves reworking many lines. As a beginner, I’m wondering whether the goal is to not layer any lines at all for a perfect firing. Is reworking a bad thing?!

Apologies for another long message! many thanks, regards

Sasha

[Peter Angel]

2) Whiting. Do you have tips on how to get the whiting smooth, and how thick to put it down? On a recent attempt firing painted float glass, I tried the Elkus newspaper flattening technique. The whiting was Champagne chalk, I found it very difficult to get it perfectly smooth. And the glass did pick up some of the whiting texture, as well as partially clouding on the back side. Admittedly I didnt pre-dry the whiting out - could this be the decisive factor? Also, do you have an experience that one chalk type works better (e.g. Champagne, Bologna etc)? And does anyone use a whiting/ plaster of paris mix as per the Reyntiens book?

Sasha

Bert Weiss once told me a method for getting whiting perfectly smooth but I don't recall it, sorry.

I'm sure Bert will be around here soon.

Pete

[Don Burt]

Hi, many thanks for your help Don, really appreciate it!

Re the backpainting, if I understand you correctly, then firing with both sides painted and unfired is not a typical practise, it being more reliable to fire each side seperately? And, when you say that firing with paint down is a calculated risk, what actually are the risks? Is this only the picking up whiting/ getting duller as you mention, or something even worse?!!

Maybe 'more reliable' isn't the best phrase. Firing stuff down is just different. Your top side paint will fire differently because it has more air, and it has a different heat experience than the stuff on the underside. Maybe it won't make much difference on Reusche Stencil Black. I wouldn't expect anything worse than a different texture, picking up a little whiting, or in the worst case falling off the glass. If you used colors with cadmium compounds or gold in it, it might be a lot different. So you would reduce some of that variable by firing all the unfired ('green') paint 'up' in multiple firings. I'm not saying you can't get a way with it, but it would be factors that I personally would prefer to control by doing multiple firings or doing all the painting on one side (maybe with multiple firings).

I’m afraid I dont quite understand your firing procedure. Are you saying that side that the back painting is fired first face up at a higher temperature, then the glass is turned over for the next firings, where the front painting is fired at lower temperatures? I’m going to be using an electric glass kiln, and wondering what high or low temps might be for my Reusche paints designed for 675C. Unless I’ve really misunderstood, that is!!

I paint with two different types of paint. One is Reusche Glass Stainers Color that fires to 682C in my propane kiln. I also use Reusche Transparent Series enamels (and some German ones) that fire to a lower temperature e.g. 593C. Those I can put on the second side of the glass that has already been fired with Reusche Glass Stainer's Color and fire them 'up' knowing that 593C is not likely to impact the first side that is down. This is pretty common practice.

Re the whiting, this was an initial test using an electric ceramics kiln. It went at 200C per hour to 660C with a 5 minute soak, then I turned the oven off, and open the vents, as it doesn’t have a programmable cool down. I’m wondering if maybe I put the whiting on too thick. It was picking up all the creases in the newspaper. I will switch to a dedicated glass kiln for the next attempt.

I use newsprint from a big artist's sketchbook. But even if you just use newspaper, I don't think you should need perfectly smooth whiting. 200C to 660C with a 5 minute soak is a lot more heat work than I put into my glass paint. You must like it really glossy? Mine turns out eggshell texture, with a little reflected sheen to it. I fire to 682C in 8 minutes with no hold. My antique glass doesn't usually pick up much texture from the shelf, and my float glass never does.
Re the brushes and consistency, thanks for the tips on handling. I think maybe I phrased myself badly. I guess I meant sable rather than simply watercolour brushes, I do in fact also use a larger sable rigger type tracer too, which as you say does deliver a minute line if handled well, which ocassionaly happens in my case!! I do a lot of thinner, lighter lines. I’m trying to get the right consistency, but with only books to go on, its well, quite a bit of guessing/interpretation too as to what that might be! So I often wonder if my paint mix is too dilute. I suppose the proof is in the kiln! As you say, the best thing is to do tests.

Yeah I get what you're saying. I'm not an expert tracer myself. There's got to be somebody over there in Munich you can take a course from.
I guess I’m aiming for variety of opacity, as sort of painterly approach. So this involves reworking many lines. As a beginner, I’m wondering whether the goal is to not layer any lines at all for a perfect firing. Is reworking a bad thing?!

You want painterly? Then you need to try a water friendly medium that stays open. Reusche D1368 is a good one. It holds a lot of paint and you can move it around as much as you want. You can dry it with heat and overpaint it. I have a terrible time trying to trace with it, so far, but I will overcome that.


Apologies for another long message! many thanks, regards

Sasha

[Buttercup]

Sasha, you can flatten the whiting with a piece of float glass or a rolling pin if you can't make the paper work for you. If the whiting is lumpy because it's holding moisture from a damp atmosphere you can dry it out in the kiln prior to flattening and placing your painted glass on it.

I've never used champagne chalk so can't comment on it. I use Alumina Hydrate which protects the shelf very well and I haven't had trouble with it sticking unless there's been a kiln malfunction or a programming error and the temp has gone too high.

Take Don's advice about getting the results you want by firing your high fire paints first, paint side up. Then if you want to fire a lower-fire paint e.g enamel, on the other side, refire with the enamel side up and the already-fired stainer side down. You don't have to fire on the opposite side unless that's an effect you want. You can paint your low-fire paints on the same side as the stainers. The second, lower-maturing temperature won't affect the already-fired stainers.

Search the archives for 'Painting and firing". You'll get lots of results. Here's a thread with some info. Jen

http://www.warmglass.com/phpBB/viewtopi ... =2&t=41353

[Sashaziv]

Dear all, thanks very much for your info and replies!

Don, Jen, thanks for the firing info, I think understand your firing procedure better now. I have thought about using enamels/ lower temp paints at some point so the info is useful. But to clarify, my original idea was get some extra tonal depth/ texture, by matting with the same Reusche weather resistant black and bistre paint on both sides. (Rather than backpainting with a different paint type) The idea was to fire both unfired sides simultaneously, thus possibly saving on one or two firings, as there will be silver stain involved later too. As you say, I guess the best thing is to test really. It would be interesting to see if the down side does in fact fire ok.

Which actually leads to another question. I’m assuming silver stain works only on clean glass - or could you fire a (thin) layer of matting, then fire a layer of silver stain on top of that in the last firing? (I'm quite keen on creating antique effects, hence the idea of using matting to creare further tecture/ tonality on the silver stain)

As for my firing schedule, from 200C up to 660C in the electric ceramics kiln, this was sort of cobbled together from various sources. I had a couple of pieces with clove oil tracing in there too, and I’d read its better to fire that slower. Actually my gum/water matted pieces came out fairly matt, I’d hoped for glossier. I think it would have been more glossy at 675C. Or possibly the paint was matted too thickly? But there was some warping of the glass too. I’d put that down to the thinness (3mm) of the float glass, but you may be right that there was too much heat in fact.

Re the whiting, yes I dont know why my glass picked up so much texture, maybe I put too much whiting down. Actually I dont mind that texture so much. But the clouding is not so nice, yes, it may be due to moistness in the chalk. Its interesting what you both say, I’ll try a different type of paper/ rolling pin/ float glass! And the Alumina Hydrate if I can find it.

Re the tracing/ line painting, I’m wondering wether it is a good strategy to leave a lot of the finer detail for a seperate, and possibly final layer, after all the matting has been done. I assuming that detail as a final layer would be crisper, effectively a finishing touch?

Thanks for the tip Don about the Reusche mediums for painting, and for the link Jen!

All the best, cheers, Sasha

[Bert Weiss]

I believe my flatten whiting technique was to use a piece of float glass and move it back and forth, using a suction cup. I am not a big fan of whiting. I usually work at hotter temperatures. I have a mix I use which is alumina hydrate and diatomaceous earth. This will stand up to fusing temperatures and is usable over and over.

I routinely fire paint side down using colors that mature around 770ºC. I do have a special protocol. First, I mix in some mica, usually either super sparkle large particle white) or mother of pearl (small particle white) The mica seems to prevent any sticking. I fire this on any surface I have, including a sandbed, fiber board, fiber blanket, kilnwashed shelf, or kilwashed slump mold. I use a water miscible medium that is slow to dry. So, first I dry it in the kiln. I would never put wet paint down. I do reverse painting beneath clear glass with this technique. There are no issues with painting on the up surface as well.

One of my big concerns with using vitreous onglaze colors is losing the sense of glassiness. (first cousin to truthiness). When I reverse paint, the colors sit behind a clear glass lens, and are truly glassy.

[Don Burt]

I believe my flatten whiting technique was to use a piece of float glass and move it back and forth, using a suction cup. I am not a big fan of whiting. I usually work at hotter temperatures. I have a mix I use which is alumina hydrate and diatomaceous earth. This will stand up to fusing temperatures and is usable over and over.

I routinely fire paint side down using colors that mature around 770ºC. I do have a special protocol. First, I mix in some mica, usually either super sparkle large particle white) or mother of pearl (small particle white) The mica seems to prevent any sticking. I fire this on any surface I have, including a sandbed, fiber board, fiber blanket, kilnwashed shelf, or kilwashed slump mold. I use a water miscible medium that is slow to dry. So, first I dry it in the kiln. I would never put wet paint down. I do reverse painting beneath clear glass with this technique. There are no issues with painting on the up surface as well.

One of my big concerns with using vitreous onglaze colors is losing the sense of glassiness. (first cousin to truthiness). When I reverse paint, the colors sit behind a clear glass lens, and are truly glassy.

But why do you fire it down Bert? why not fire it up?

[Buttercup]

I'm not trying to answer for Bert, but I suspect he's firing paint side down to keep the clear, glossy, unpainted side up in bowls or sinks. As Bert stated, his mica mix-paints don't stick to the molds. .......maybe that's why? Jen

[Bert Weiss]

I'm not trying to answer for Bert, but I suspect he's firing paint side down to keep the clear, glossy, unpainted side up in bowls or sinks. As Bert stated, his mica mix-paints don't stick to the molds. .......maybe that's why? Jen

Yep. I like working behind clear glossy glass. And the paints don't stick with mica mixed in.

[glasstech]

From your experience, Bert, what is the minimum proportion of mica to paint/enamel to achieve the "not stick to the shelf" result?

[Bert Weiss]

From your experience, Bert, what is the minimum proportion of mica to paint/enamel to achieve the "not stick to the shelf" result?

I don't know. What I do know is that the more mica you mix in, the less glossy is the surface you get. I never got to the point where my work stuck. For that matter, I don't recall ever firing with just vitreous enamel on the bottom. Maybe I solved a problem I didn't have??? Regardless, I do like the result of mixing micas in.

[Sashaziv]

Dear all, thanks for all the useful info! A few side questions if I may!

1) I've done similar tracing on 1/8" float glass, and spectrum 96 fusing glass. If I want a glossy sheen, is it possible that the ideal soak firing temps for the glasses may be very different? Is it better to fire different glass types separately?

2) Cleaning - so far on my float glass, I had little success cleaning with ethyl alcohol or acetone. (I'm wondering in fact if this glass has some tricky chemical factory coating!!) Cleaning with my reusche glass paint seems to work though. Although this looks ok, can the glass paint cleaningm leave residues that will affect the firing?

3) Kiln Wash - I've been offered the use of a kiln where there are some kiln washed boards, which have been fired some times. Is there a way to assess if the kiln wash is still useable/ in good condition? Or if a project is precious, it is better to put just fresh kiln wash for each firing?

Many thanks! All the best

Sasha

[Don Burt]

Dear all, thanks for all the useful info! A few side questions if I may!

1) I've done similar tracing on 1/8" float glass, and spectrum 96 fusing glass. If I want a glossy sheen, is it possible that the ideal soak firing temps for the glasses may be very different? Is it better to fire different glass types separately?

2) Cleaning - so far on my float glass, I had little success cleaning with ethyl alcohol or acetone. (I'm wondering in fact if this glass has some tricky chemical factory coating!!) Cleaning with my reusche glass paint seems to work though. Although this looks ok, can the glass paint cleaningm leave residues that will affect the firing?

3) Kiln Wash - I've been offered the use of a kiln where there are some kiln washed boards, which have been fired some times. Is there a way to assess if the kiln wash is still useable/ in good condition? Or if a project is precious, it is better to put just fresh kiln wash for each firing?

Many thanks! All the best

Sasha

I don't know the answers to any of the questions....but I had a question regarding the float glass cleaning: What bad thing is happening that makes you think ethyl alcohol or acetone aren't successful cleaners? (other than the fact that acetone is nasty to smell). I clean my glass before painting with an ammonia free glass cleaner. The only issue I have is that occasionally the wet paint will crawl way from the trace line when first applied. But that is not always a glass cleaning issue. And it can be resolved with additives to the paint.

[Peter Angel]

And it can be resolved with additives to the paint.

Don, what additives?

Pete

[Bert Weiss]

I use Glass Plus to clean my glass. It is an ethyl alcohol based cleaner. Yes glass paint is a good cleaner as well. Windex, an ammonia based cleaner will leave scum after firing.

I think the additive would be a tiny amount of dishsoap like Dawn or Joy.

The temperature you fire to has only to do with the kind of vitreous paint you are using. If the glasses are thick, float and fusing glasses anneal about 80 degrees apart. If the glasses are thin, a shutoff will probably anneal both.

Kilnwash has kaolin in it. The kaolin goes through a quartz inversion, which eventually leaves scum on the bottom of glass. If you are just firing paint around 1250, you can fire over and over with no issues. If you are going over 1400, you should put on a fresh topcoat.

[Don Burt]

And it can be resolved with additives to the paint.

Don, what additives?

Pete

Soap, Kodak Photo-flo 200, or Ox Gall, or breathing on the glass so that it fogs before painting. The last solution works the best, but the Ox Gall is a much cooler sounding solution. And I think Ox Gall may be now a synthetic equivalent rather than something from a inside of a cow. In an older thread about this topic over on the American Glass Guild discussion board, some knowledgeable people still insist it is a glass cleaning issue. I'm serious about the breathing on the glass. I was kind of crestfallen when I had spent money on Ox Gall and Photo-Flo 200 and then tried the breathing thing. But anyway, I fill up a Sriracha bottle with water and add a few drops of one of the chemicals and use that in all water/gum paint mixes, and it works.

[Sashaziv]

Hi there, thanks Don & Bert for the helpful responses, appreciate it!

Don, re the cleaning, the acetone seemed to leave a kind of residue, so I gave up on that quick! The ethyl alcohol cleaned better, with less residue, but afterwards there was a fair amount of resistance to tracing, as if there was grease remaining on the glass. Plus the glass seemed more statically charged. So I then cleaned again with glass paint, and then everything was fine. My theory then was that cleaning with glass paint creates a kind of scouring action, which seems to remove the grease/ resistance better?

All the best, Sasha

[charlie]

[quote="Sashaziv"]Hi there, thanks Don & Bert for the helpful responses, appreciate it!

Don, re the cleaning, the acetone seemed to leave a kind of residue, so I gave up on that quick! The ethyl alcohol cleaned better, with less residue, but afterwards there was a fair amount of resistance to tracing, as if there was grease remaining on the glass. Plus the glass seemed more statically charged. So I then cleaned again with glass paint, and then everything was fine. My theory then was that cleaning with glass paint creates a kind of scouring action, which seems to remove the grease/ resistance better?

All the best, Sasha[/quote]

acetone is oil based, so i would guess that there will always be some residue left after the volatiles evaporate.