54 thoughts on “How to Fire Stained Glass – 12 Points You Need to Know”

1. Helpful overview, thanks. My question is, have you tested firing silver stain on fiber paper vs. firing it on whiting?

   Best,
   Peter

   • Yes. And in our experience, fiber paper was a less stable and less predictable ‘environment’ on which to fire our stain than whiting.

     For instance, even if one lot of fiber paper works fine for stain, I can do nothing to be sure the next lot will work the same way.

     The reason is, I have no control over how it’s made.

     Whiting, on the other hand, is simple.

     See this window here. The owners called us in because one of the central rectangles was missing: they wanted us to make a copy.

     The sample pieces all worked fine: they were small enough for us to fire on our trays and whiting.

     This lured us into a false sense of security: we then made a full-size piece and, because it was too big for our trays, we fired it on fiber paper.

     It didn’t work.

     Now, thinking methodically, we couldn’t discount the possibility that the different sizes were to ‘blame’.

     On the other hand, the simplest variable to eliminate was … the fiber paper.

     So we made another full-sized piece and next time sprinkled whiting as evenly as possible across the boards which form the bottom of our kiln, then pressed it down.

     The next firing worked fine, as you can see.

   • Thank you!
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3. Hello everyone,

   This is another great post. Stephen: your posts are always very useful and help a lot in my art work at my studio.

   Thanks for sharing.

   All the best,
   Hassan

   • Hi Hassan,

     Thanks for your message. Glad it’s useful. Remember, whenever you have questions, just write and say.

     Best,
     Stephen

     P.S. When firing propylene glycol (which is wonderful) like you see in The Master & the Beast, we just slowed down the rise to the first soak at 100 Celsius / 220 Fahrenheit and kept it there for 15 minutes. Then up and down in the usual way.

4. I just had two mild steel frames made and am putting fiberboard in the frames then topping this off with about 1/8th to 1/2 inch of whiting (which was not easy to find here in the U.S.!) I am very excited but I wanted to make sure before I use this in the kiln: the fiberboard manufacturer says I should coat it with hardener before I use it. Do I need to do this if I am just using it to cover the bottom area in my frame? – The fiberboard will never come in contact with the glass.

   Then the bigger question is: can I put this mild steel frame on the floor of my kiln? Is the metal going to heat up differently than the fiberboard and then crack a brink in the kiln? Do I need to place the whole “system”/tray on a kiln shelf off the floor of the kiln? I am ready to go but something about heating metal in the kiln makes me nervous – probably because of the advent of microwaves and the no-no’s about metal in them.

   • A quick reply for now because you’ve asked urgent questions.

     First, I am certain we didn’t harden our fiber board before using it in our kiln trays. But it is likely we did fire off its fumes before we first covered it in whiting: this is where you take it through a slow firing cycle and burn off various chemicals. This gives off lots of very ugly smells, so be prepared and open up your doors and windows. It’s just the once this happens. Once is quite enough though.

     Second, yes, you do place your mild steel tray on top of a kiln batt (or shelf). The batt is usually made from a general purpose material like mullite or cordierite. It’s the same as potters use, so a company which sells accessories to potters will surely have what you want. The batt sits directly on the bottom of the kiln; the tray, filled with whiting, sits on the batt. The batt does not require any special preparation each time you fire.

     Third, just to emphasize, our trays are made from 4 lengths of mild steel “L-section”. This means there is a fairly large rectangular hole in the middle: it’s this hole which the fiber board “plugs”. I believe it’s also the fact of the hole which means you don’t get warping.

     I hope this helps. Ask more questions as they occur to you.

     Best,
     Stephen

5. Stephen,

   Gracias por el material que siempre recibo, excelente. lte mando un abrazo enorme y saludos a david y tu familia.

   Rubèn

   • Hi Rubèn,

     That’s a pleasure. I’m glad it all helps. And always our best wishes to you.

     Best,
     Stephen

6. Thank you for your help. Well, now I am ready to try out the whiting. You are both so generous with your time and knowledge. I am very grateful you are around. I will open the doors and get the stinch over with. I have indeed heard that it really stinks to fire (the fiber board).

   • Virginia,

     You may not need to use an alumina hardener on your fiber board, but if you don’t, the board is quite soft and rapidly degrades. The addition of the hardener will make the board very durable. Follow the manufacturer’s instructions. It becomes almost as hard as a kiln shelf, but much lighter and will not thermal shock.

     Try ceramic supply companies for whiting (calcium carbonate). It is easily available. I get mine from a local paint company that compounds their own line of paints. This is in Iowa.

     • Thank you for your help here, Robert.

     • I have always used powdered plaster of paris, (gypsum?) as I was taught at college in the ’60’s. I don’t know if this is what you call whiting in the States, but I don’t think so. Finer than Whiting and usually easier to get hold of. And yes, as the last guy said, if you don’t harden your shelf, it will warp or disintegrate quite quickly, as the original hardener they use burns out.

7. I find my 240v kiln is quite inconsistent, and its major inconsistencies occur when it is a hot summer day so I would definitely advise keeping a very detailed log for anyone with a new unfamiliar kiln. For the first 2 dozen firings I logged the ramping temps every ten minutes so I have a good indication of fluctuations and what sort of time frames are needed for different types of paint finishes on different glasses. I find some glass, red especially, needs special attention as it seems softer than most other colours – that’s my experience anyway. There’s nothing more fear-inducing than sticking several hours of painstaking work in the kiln hoping for the best!

   Now, do you have any suggestions about reducing water-based matt burn-off: they seem to lighten significantly after a smooth finish firing? I find I have to keep before and after matt samples to ensure I am going to have a finished piece with good contrast, not a light “muddy shaded piece of glass.

   I love the words of wisdom by the way: thanks!

   Rhyce

8. Hi Rhyce,

   Thanks for joining in: yes, a detailed log is definitely the way to go either with a new kiln or with a new project which calls for new / modified techniques.

   You ask about reducing water-based burn-off.

   OK, this is when the fired painted glass you remove from your kiln looks lighter than the unfired painted glass you put into your kiln.

   It’s a fact: about 10% or 15% of the ‘darkness’ of your lines and shadows is lost in firing …

   But not if you ‘seal’ your water-based painting with a wash of oil-based paint or glycol-based paint.

   So, if burn-off is giving you problems, I’d definitely suggest you paint some simple pieces, and then experiment with oil or glycol. It makes a huge difference.

   People who get our newsletter also got this great video right here which I’ll make public just to show people who don’t get the newsletter what they are missing: just watch this glass painting video of using oil on top of water-based paint and you’ll see what I mean. OK I admit the video is about shading (not preventing burn-off as such). But that’s an added benefit: you can shade more easily and also reduce burn-off when you seal your water-based glass paint with something that is not water.

   Second, this new glass painting DVD shows you two full-length demonstrations of oil and also glycol.

   Best,
   Stephen

9. estimados DAVID-Stephen
   Excelentes tus comentarios mira yo estoy usando como desmoldante papel ceramico bullseye y realmente es espetacular mis resultados solo transmito mi esperiencia
   gracias a ustedes siempre informando
   un abrazo de argentina
   rubèn

10. I flatten or slump bottles. Is there ANY glass paint that I can use to paint lettering such as initials and quotes on the glass bottles that I can kiln-fire at the same time as when I slump the bottle that is bright and permanent.

    Thank you!

    • I’m sure there is though I have not done the tests myself. In your position, I would buy a small quantity of Reusche tracing black (DE401). Then do some experiments until you get the result you want.

      Please note: if you slump and fire the glass paint in single firing, whatever you paint will certainly be distorted at the same time as the bottle flattens. This may be fine; or it may not (your lettering will definitely change its shape). If distortion is not acceptable, you’ll need two firings: one to slump and one to fire the paint.

    • If you find a potters’ supplier, you can get gold, bronze, silver or even platinum lustre. It is dark brown before firing but you can paint it on with a fine brush, cleaned with spirit. This fires at between 670 – 800 ish and leaves a permanent gold/ silver/ bronze design. Ideal for lettering, if you have a steady hand, and it fires at the right temperature for slumping.

      • … Forgot to say, it’s not cheap, but it does go a long way!

11. Happened upon your comments here … It’s great to hear open discussion about glass painting!

    I am also a glass painter and welcome any banter about the medium. (It’s a love /hate relationship at times!)

    Thanks!
    Bruce

    • Hello Bruce,

      I’m glad you found us, and I hope you’ll find many useful discussions here.

      Best,
      David

12. Hi!

    I really like your website!

    Two questions please …

    1 At what temperature does paint stick to glass? (Have to paint two layers and just want first layer to stick so we can save time as second firing will gloss both.)

    2 If we don’t have gum Arabic, what would you suggest to save on firings? (We tried mixing the paint with vinegar and it didn’t stick.)

    Thanx a mil!

    • The temperature at which glass paint sticks to glass – what you’re after is called a ‘tack firing’ – depends on the glass paint, your glass, your media (e.g. water, oil, glycol etc.) and your kiln (since ‘1020’ in one kiln is not necessarily the same as ‘1020’ in another kiln). So you will need to do some tests to establish the minimum temperature you require. Since you make it clear you wish to save time, you might wish to re-consider your plan and choose instead to fire each layer separately and properly.

      Vinegar can certainly work, so you will just need to practice till you get the proportions right, and also the technique. Another option is to get some gum Arabic.

      Overall, it seems you might do better to pull back and slow down and test and practice till you get the kind of results you will be proud of if your glass were fortunate enough to survive a couple of hundred years.

13. Hi great info and website! I’m a beginner, so very useful info on firing! A question – I had a look at your firing schedules pdf. I was wondering if you could explain your annealing schedule in a bit more detail? Many of the other schedules I have seen elsewhere, especially for thin 3mm glass, simply turn off the kiln after the main soak at 660-675C, so I’m interested in yours as it is quite different! Is it based on scientific principles?

    I was wondering, why is the first ramp down to 560C? Also, re the 3 hours at 10C/hr from 560-530C – for my 3mm thin glass, this seems a fairly high temp to hold for so long, or is this not the case? What are the benefits of these stages?

    Many thanks, Cheers, Simeon

    • There’s a good reply from Oriel here (thank you, Oriel). Thing is, none of this is absolutely precise: it’s rough and ready – even the temperature is rough and ready because we have no guarantee that when your kiln controller reads ‘660’ it’s at the same temperature when ours reads ‘660’. So it’s important to take things in this light.

      Next, as Oriel says, some of the glass you get may not be properly annealed in the first place. And that’s why a slow descent is generally a good idea: even if you haven’t gone above the critical temperature for that specific sheet of glass, you can use this opportunity to heal any damage which might have occurred when the glass was made.

      Now we choose to descend slowly. Reason is, it’s easy enough to do and potentially damaging if we don’t. So the benefits outweigh the costs by far. For us.

      It’s your call what you do in your case.

      On the one hand, you must find the schedule which achieves the effect you want (e.g. glossy, dry etc.); on the other hand, you must consider whether to adapt this schedule to remove real threats and/or give you peace of mind.

14. When we fired glass paint at college, we just cooled slowly/naturally, and the glass was always fine. I think the firing cycle holding at 560* is an automatic reaction from people who do fusing, because that’s the temperature you hold if you take glass higher than the 675*. It needs annealing. We never had breakages by not holding though, so I shouldn’t worry. I have in fact, taken a couple of sheets of Lamberts up to 670* because after the first cut, which flew sideways with a bang, I decided they were badly annealed in the making (Apparently about 10% are!!) This cured the problem, & I never held it at 560*. Good luck

15. Hi there, thanks to you both Stephen and Oriel for the replies, very useful info! I guess I was partly asking about the logic behind the different temps, as this is the first precise annealing schedule I’ve come across. I’m still a bit foggy as to what I would do if I wanted to adapt it though, as it would be total guesswork on my part! But firstly, I think I’ll try the schedule and see if it works for me! Many thanks, Simeon

16. Can you use a old top loading ceramics kiln to fire painted glass? I worked at a studio years ago and we used a gas kiln. The ceramics kilns are easy to come by used but I’m not sure if they would fire properly.

    Thanks for the article

    Dane

    • Whatever works. (I’ve heard of folks who just build a big bonfire …) Mainly a question of figuring out the schedules for the results you want. Lots of tests, lots of photos: in time, it’ll all become second nature.

      Best,
      Stephen

    • Virtually any kiln should do, as long as the shelf is flat and you only fire on one level, otherwise you might get breakages where glass heats unevenly because of overhang of higher shelf. Don’t forget to cool naturally with kiln closed and don’t open before glass is at about 70* C

      • Thanks for all the feedback.

        Can you explain “glass heats unevenly because of overhang of higher shelf”? I was thinking of maybe stacking shelves why would there be overhang?

        Dane

        • If the elements are in the lid, there will be more heat going down the sides and heating the edges of lower shelves. The centres will stay cooler as they are out of direct line of the elements. This can cause uneven heating and breakages can result. Probably better to play safe if you can.

          • What if all the coils are on the sides? Would that present an issue?

            Dane

            • Probably less so, though I’ve never had a kiln with side elements so never tried. Go for it and see! (leave good space between shelves though, I would suggest.) If stuff starts breaking… don’t do it again. 🙂
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19. I would love to know how to fire painted wine glasses in a kiln; glasses that are totally painted gold, silver, mother of pearl etc. Similar to glasses I’ve seen on sites by Debbie the glass lady’s decorative chalices and goblets. Do you have any suggestions or instructions? Currently I handpaint glasses and bake them. I would love to begin using a kiln.

    PAMELA C.

    • Hi Pamela,

      Sorry, can’t help you here. Just don’t know about the kind of things you’d like to do.

      Best,
      Stephen

20. Hi
    I’m trying to produce lustre paints on large slumped platters. I’m slumping and firing the lustre at the same time, but the lustre is “scrunching up” – I guess it’s too high for the lustre. If I slump first then paint on the lustre and fire, a) it’s difficult to paint and b) the lustre is running in the early stages of firing. Also, to fire the lustre I am going through the whole glass firing techniques with holding and annealing, etc, should I be able to go straight up and down?
    Finally, should I fuse the glass first?
    Thankyou
    Meredith
    Any suggestions would be most helpful.

    • Gosh, I’m sorry, but lustres and slumping are completely outside our experience. I can well imagine the tests are sometimes frustrating when you don’t see progress. But I assure you that a methodical, steady approach will get you there.

      Best,
      Stephen

21. Hi Stephen, great advice, so freely given. I’d like you just to clarify that when you say you can paint layer after layer of paint before firing, are you using water & gum arabic only with your paint pigment or something else?
    Many thanks,
    Jennifer

    • Sorry for the delay: I wrote an answer, posted it, but it appears it wasn’t published.

      Yes, many layers using glass paint mixed with water and gum Arabic.

      But always it depends on the effect you want to achieve. I never mean to suggest there’s an special virtue in painting lots of layers. All I mean is, it’s possible.

22. Hi, I really enjoyed what you had to say. Very helpful. Thanks. I’m wondering if you can give me some insight into some paint problems I’m having. Yellow on green fades away entirely or at least some and so does red. It’s not as bad, but not good. Also, I had some bright orange on a white glass background completely disappear. The surface I painted orange is back to white with a brown tinge on part of it. Any thoughts on what’s going on?

    • Hi! How frustrating for you. Unfortunately we can’t advise you: it sounds like you are using enamels – we rarely use them, so we don’t have the experience to guide you here. The first point to establish though is whether the enamels behave strangely on all glass. Best – Stephen

23. Hi can you suggest an ideal firing/annealing program for stained glass? I did some work years ago but was never confident of a program. I have a kin with a digital controller.
    Kind of you to help

    • I should have added that I am firing Reusche stencil paint
      Thanks
      Stephen

      • Sure. I can tell you our standard schedule. You can paint a test piece or two, try our schedule on the first piece, see how it works, then adjust the schedule and test it on the second piece, and see how that works.

        We use Celsius. If you convert the figures, just round them to the nearest 10.

        So nearly always we go to 100 c and rest there for 15 minutes. This makes sure our paint is thoroughly dry before we really start.

        Then we go to top temperature. Now this depends on the paint, on the glass, on what you want the paint to look like (dry vs. glossy), for instance. It also depends on your kiln: yes, our 660 c for instance may not be the same as yours. So for Reusche tracing black, our second phase is, we go to 660 c as quickly as our kiln allows. We use electric kilns so this may take 2.5 hours. A gas kiln on the other hand will do it in 12 minutes …

        Sometimes we soak the glass for a few minutes. This mainly depends on whether there is paint on both sides.

        Then we decrease the heat as fast as our kiln allows to 560 c, and stay there for 15 minutes.

        Then we decrease to 530 c over 3 hours.

        Then we let the kiln cool at its own rate.

        This is a cautious schedule. It’s possible to be far less cautious e.g. straight up to the top and straight down. It’s also possible to be far more cautious e.g. go up more slowly, go down more slowly.

        So why not use this for your first firing and see how it goes?

        Best,
        Stephen

24. Can I microwave kiln-fired glass. If so what temperature and length of time?

    • The temperature and time depend on the paint: you can get this information from the paint’s manufacturer. As for whether you can use a microwave to fire your painted glass, this depends on whether the microwave goes hot enough and on whether this use is something which its manufacturer allows. Again, the manufacturer is who’ll advise you. (There certainly are ‘microwave’ kilns for glass paint: myself, I wouldn’t use the same kiln for doing anything with food. So an ordinary kitchen microwave is out of the question.)

25. very helpful!

26. Hi, thank you. Sometimes I think people who write online just quote other people … For example ‘soak, hold, fuse, slump, DPH’.

    I just want to fire some paint onto glass.

    My kiln gets to 510C in 12 mins and isn’t adjustable. On line it says 300F DPH to 950F hold 30min. Mine can’t do this: any ideas?

    • Hi, I’m so sorry because I feel I don’t understand your question. Are you asking for ideas why your kiln won’t get hotter than 510 Celsius: is that it? If so, is it possible that 510 C. / 950 F. is the limit of your kiln? If there’s a label on your kiln, it’s worth contacting the manufacturer.

      You mention your kiln isn’t adjustable. Well, if it isn’t, that’s the end of it. On the other hand, it’s often the case that a kiln (which is just a very hot oven) becomes adjustable by means of a controller. That is, the controller (not the kiln) is what makes the kiln adjustable. So you’d need a controller: again, the manufacturer would help.

      I’m sorry I can’t help more.

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