Recently I held a small workshop in home made glass clay and would like to share the result and recipe with you guys as I got some hints for the firing schedule from a discussion in here :) Here's a "before" and "after" pic of some of the pieces made during the workshop (sorry about the yellowish photos):
(http://www.rangifer.se/exp_img/glaslera1_before.jpg)(http://www.rangifer.se/exp_img/glaslera1_after.jpg)
Simply mix 1 part cellulose based wallpaper adhesive powder with 6-10 parts glass powder frit, and add water until you have clay. Grind the adhesive powder with a spoon before you add the glass powder to avoid lumps in the glue.
Use a dust mask while working with the glass powder, especially if it contains lead. Also check the safety sheet for the adhesive to verify that it doesn't give off anything nasty when burning.
You can also make some wallpaper adhesive according to the instructions on the box and add small amounts of it to glass powder until you have a nice clay, but I found it easier to avoid lumps if I mix the powders before I add water.
Shape the clay with tools, cookie cutters or by hand. You can also add bits of glass, frit, cubic zirconias and other fusible decorations. If you add glass you should probably stick to the same COE as the glass powder (I've used Bullseye throughout). The clay shrinks a lot when it is fired so keep that in mind when planning your design.
When the clay is completely dry you fire it in a fusing kiln. I heat slowly (200 degrees/hour or so) up to 500 degrees and let it sit there for an hour so that the cellulose burns off completely. Then I ramp up to about 710 degrees and fuse for 10-15 minutes (for Bullseye COE 90 glass). Anneal and cool as usual for fused glass. While the cellulose burns off it smells strongly of burning paper, so keep a window open and turn on any ventilation you might have.
The pieces in the photo above were fired at 700 which leaves a slightly grainy texture. Higher firing temperature will give a smoother surface, but if you go too high you'll lose detail.
Both transparent and opaque glass powder works. Transparent powder won't make the result transparent though, just translucent. Some transparent colours turn too dark and must be "diluted" with clear. Clear and white turn a bit greyish, so they're not nice on their own. Yellow turns murky greenish, that's the only glass I've given up on entirely.
Amazing, which glass did you use, a 104 coe?
Nina
Thanks for sharing. It looks really interesting. I'd definitely like to have a go one day. Can you store surplus clay to use another day?
Cool! Thanks for the recipe! ;D
You're all welcome ;D
I use Bullseye COE 90 glass since it's easy to find in powder form. I bought it from http://www.warm-glass.co.uk
The clay dries very slowly and if you cover it with some plastic it will stay good for a few days at least.
WOW!!! Lovely results!! Thanks for the recipe Noora!
Surely this what was always called pate de verre or am I missing something?. When I do this with students we use glastac instead of wallpaper paste because some pastes have fungicides which can discolour the glass and there is less smell.
I know this method as pate de verre too, when i learnt we used wallpaper paste, as we didnt have any glastac, but were told that there must not be fungicide in the paste.
but we only did things in plaster moulds to make bowls etc, so the stand alone pieces here are really interesting :)
Can you manipulate it like a clay in your hands and roll it out, etc though Glyn? I thought that was the difference.
They look fab, thanks for sharing.
Pate de verre is french for glass clay, non? ;)
This is amazing. Thank you for sharing Noora. As an ex painter and decorator, it made me smile to think that I have now found a link with old and new trade ;D I will give it a go sometime. I would be interested to have the firing schedule for 104 glass.
Thanks again
nete
Wow - that looks like fun - bookmarking for a proper read later - thanks for posting x
Yes, it is a variety of pate de verre (which is glass powder and any binder that works for your particular application). I prefer to call this variety glass clay since it can be formed just like clay. It is inspired by a recipe at Kaiser glass that they call glass clay (CMC and powder glass), and the commercial GlasClay product (which I don't know what it contains, just that it's expensive). Sorry I forgot to mention that, I like to give credit where credit is due :) It's not my own invention, but I haven't found any exact recipe for wallpaper paste based glass clay, so I had to do some experimenting to a good recipe and method to mix the paste in order to avoid residue and lumps.
I've tried glasstac (or some similar fusing glue) but that made a crumbly mass that couldn't be easily shaped without a mould.
Thanks for the tip about fungicide! I've checked that the wallpaper paste is safe to burn and doesn't contain anything "odd" but didn't really know what to look for in particular.
Also, I have to use distilled water as we sometimes get both rust and copper residue in the tap water (yes we need new plumbing...).
Quote from: nete on October 30, 2012, 10:37:30 AM
This is amazing. Thank you for sharing Noora. As an ex painter and decorator, it made me smile to think that I have now found a link with old and new trade ;D I will give it a go sometime. I would be interested to have the firing schedule for 104 glass.
Thanks again
nete
I would use the same firing schedule and run a test with one item and then adjust up or down if necessary. Bullseye (COE 90) and 104 are close enough to use the same annealing schedule, so I would imagine the firing schedules can't differ much either. I have no idea where to get 104 powder though, that's why I use Bullseye.
Noora this is fabulous thankyou so much for sharing
I have only used pate de verre in plaster/silica moulds so glastac worked fine I will definately try wallpaper paste to see the difference. Pate de verre translates as glass paste, wouldn't it be argile de verre to be glass clay?
Just had a thought. Would flour and water work cos people used to use that as wallpaper paste? I'm always nervous about experimenting as frightened I'm going to ruin my kiln!
Nete
I wouldn't try flour and water it would leave too much residual carbon which would discolour the glass. In the old days they used milk as a binder, the casin in the milk acts as a glue. It works ok but the smell during the firing is awful.
Give that a miss then. Thanks Glyn.
Nora, I
I'm reading your thread on glass clay, but can't see your photos of the work you did with it. Would you please post them again.
Thank you, chloe