High fire glaze on a low fire clay

[origami_blackbelt]

I'm working on a final project for school and I was wanting to experiment with melting a low fire clay piece in a high firing. Now what my concern is that the glaze might not bond well with the clay.
I'm assuming that theoretically the glaze should bond with it just fine and that as long as the glaze is still covering the melted piece than technically it should still be functional.
Has anyone ever tried that before??? I also wanted to know how much a cone 04 piece would melt in a cone 6 firing? Say if a cone 04 teapot was fired up to cone 6 do you think it could still maintain its form?

[Daesul]

I think you'll find that the clay form will sag out of shape. You would need to be careful that it didn't sag right onto the kiln shelf and get stuck to it! So maybe you could place it onto a slab of biscuitware to protect the kiln shelf in case that does happen.

I've never deliberately tried this but I seem to remember it happening at the art centre I used to work at, and the piece just melted onto the shelf. But that was a cone 04 piece that got fired to cone 8, so quite a big difference.

[Cuckoos Nest]

Why do you want to fire it so high if it's a low firing clay? And what shape is it? Some pieces will sag out of shape more than others depending on the weight distribution.

I'm intrigued . . . . . .:confused:

[KEceramics]

Having done it myself, and been told off for ruining a kiln shelf, and I mean TOLD OFF!!!! it's not worth bothering with. The clay will "melt"...simple as that, you end up with a nasty looking mess on a kiln shelf that doesn't come off and a very cross technician (in my case) or teacher.

[toppotter]

So you talking about another 160 - 180 c in temp. Depending on the clay it might take the temp but probably sag and bloat (red clays especially). An earthenware glaze will run like crazy at that temp, unless you use a stoneware glaze .
Either way its going to make a mess of the kiln shelf and if the clay bloats it also might spit on to other items in the kiln.
On balance unless you are willing to build a sagger to put your experiment in to protect other work in the kiln and the kiln itself you might want to think again.
regards
Robin

[origami_blackbelt]

That's a really good idea. I hadn't thought of making a sagger to place my piece in. It was actually my instructor who suggested it. That's the main reason why I'm trying to find out how a high fire glaze would bond to a low fire clay. I understand that it will melt, there's a big mess in the kiln room where the thermocouple got knocked out of place and a piece melted to the shelf and its a gross mess, but that was to a much higher firing than what I'm planning to do. I was thinking of a teapot as a general form but I might choose a different form if it doesn't work. The criteria of the project is functional/dis functional so my premise is to make a piece that looks dis functional but is functional and what looks more dis functional than a melted ceramics piece. But i want to keep the bright colours of the glazes and that's why I'm thinking of using cone 6 glazes on cone 04 clay. Do you think the glaze will bond with the clay???

[toppotter]

Probably but why not fire up a test piece?

[bonechina]

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[Melissa]

I really would not do it! When I was at college I fired some black earthenware up to 1260 (by accident!) - The piece melted not only to the kiln shelf but down the side of the kiln and in to the elements - I was told off good and proper - and then reminded through out my time at the college of how I had wrecked a kiln!

[Melissa]

oh meant to say, I agree with topotter - do some test pieces - they should like that if you are in school! adds to sketch book work!