Powdered glass questions

[Jane C ♫]

Nice!

Bear in mind though that ceramic and glass have different expansion rates, so you're likely to get cracks / crazing later.

[Moira HFG]

Here's my effort. As you can see, I couldn't pile up enough to fill the holes, either!
The clay shapes are 6 to 7mm thick.
I coated a bit of kiln shelf with 4 or 5 laters of Primo, and took them up to 820ºC, holding for 12 minutes.

Here's the clay shapes piled with frit; bits of scrap Artista in the rectangle, Bullseye in the arch shape:

image by sleepychamaeleon, on Flickr

and fired:
(note that although I cleaned off the clay with a paintbrush, a bit of frit pinged off and stuck to it!)

image by sleepychamaeleon, on Flickr

As you can see, the Bullseye has completely melted and pulled away from the edge; the Artista hasn't melted fully but has settled into half fused ripples - I quite like that actually. There's a few gaps around the edge, as you can see with light behind:

image by sleepychamaeleon, on Flickr

To avoid spoiling the patterns, I may cut a piece of (compatible) clear to fit over the inside shape, and refire.

Next time I might try mixing the frit with a bit of binder - diluted PVA glue for example - so I can mound it up higher without it overflowing.

[ajda]

Really interesting stuff Moira - I agree, the part-fused effect looks good. Any sign of cracking? Were the clay shapes fired first? Does the Primo give you a really good surface finish - any chance of some close-up photos?

[Pat from Canvey]

Thanks for posting the before and after Moira. It's really interesting. Next stop, stained glass windows in clay frames? I seem to remember seeing some many years ago but they might have been set in concrete rather than clay. Can't remember. Here you go, I Googled stained glass in concrete, https://www.google.co.uk/search?q=stained+glass+in+concrete&client=firefox-a&hs=bfu&rls=org.mozilla:en-GB:official&channel=sb&tbm=isch&tbo=u&source=univ&sa=X&ei=4o-FU7i3JYHsO8KpgPgL&ved=0CDsQsAQ&biw=1188&bih=766

[Moira HFG]

My aim was to make some tiny, jewellery-sized stained glass windows. I tried to fire the clay first but only part succeeded, the whole sad saga is here:
http://www.frit-happens.co.uk/forum/index.php?topic=44294.0

I soaked one of the (other) pieces in warm water to see if it turned back into clay and it didn't so I went ahead!
No sign of cracking yet, time will tell.
I use Primo a lot, after having some problems with things sticking to ordinary batt wash. The surface is maybe not quite so fine as on Thinfire, but pretty good. Here's the back:
IMG_0174 by sleepychamaeleon, on Flickr

Some interesting pics there Pat. I've read about glass in concrete, I think it was called Dalle de Verre. I suppose the advantage of that is that you work the glass first so you don't get the shrinkage problem.

I could make my little windows that way if I used one of the air-drying or low-fire moulding materials. But I wanted the contrast of smooth translucent glass against grainy fired clay.

I need to find someone nearby with a pottery kiln to pursue this!

[Pat from Canvey]

I made 3 glass mosaic stepping stones many years ago using the reverse mosaic method. The stones were made with a bag of ready mixed concrete. They're still in the garden and are in good nick. This method is somewhat similar.http://www.mosaicgarden.info/Techniques.html
I think I used one of the methods here, http://siliconfolly.com/manuals as I was a member of the glass forum there at the time. This one was just done on MDF board and grouted with ordinary tile grout,

[ajda]

Thanks for all the info... Those roses are impressive, Pat! Yes - dalles de verre, Moira, like thick glass tiles, shaped by flaking and chipping, then sometimes set in cement or stone resin. We have a piece - see below, not a great photo, should have waited till the sun was shining behind it - made by the Loire family in Chartres, which was given us as a house-warming present. We visited the Loires recently ourselves, had lunch with the current head of the family, Jacques and his wife Micheline and a fantastic tour of the workshops - now that's a place to inspire any glass lover!

[Moira HFG]

Gorgeous roses, Pat! And that's a lovely piece, Alan, very dramatic. It's good to hear this is still being made.

Here's my latest news on the ceramic/casting front. I cut a piece of clear Tekta to cover the arch shaped one, and topped up the rectangular one with more fragments of Artista glass, and refired them.

Results: the clear cap domed nicely over the arched window, magnifying the colour below which is great but hard to photograph. There is a small crack in the bottom left corner unfortunately. i don't think this was due to the firing, I think it is down to the shrinkage issue Jane mentioned.

The rectangular one came out fine. The glass didn't flow quite to the edge so no cracking problems, but it will need a spot or two of glue to keep it in place.

image by sleepychamaeleon, on Flickr   image by sleepychamaeleon, on Flickr

I have found someone to fire this clay for me properly now, so I'm going to press on with this! I have some ideas...

Katy, have you tried again? How are you getting on?

Has anyone else been successful at combining ceramic and glass?

Moira

[Zeldazog]

Thanks for posting Dalle de verre Alan, been trying to remember what it was called!

An artist I like is Andrea Walsh - her pieces are ceramics and glass look like a layer of liquid inside the forms - you want to touch the surface as it is hard to believe it's not coloured jelly!  But it is glass.



I met her at Ceramic Art London preview; after not eating all day, followed by a large glass of wine, she was relaxed enough that she hinted at how her work is done, without telling me everything.  You'll have to do your own research 


The problem with combining glass and ceramics is to do with expansion and contraction rates.

As we all know, combining two types of glass with different COE (coefficient of expansion = expansion rates) will almost always result in cracks - if it doesn't come out the kiln like it, chances are it will happen later anyway.  Clay goes through a similar process as glass during a firing cycle, in addition to an element of shrinkage on first firing (due to driving out of all water in the clay body) - even when it has been pre-fired, ceramic still expands and contracts in the heating/cooling cycle, and just like different glass, this happens at different times.