moulds

If this is to be a hump or slump mold, where you just drape a sheet of clay over the mold and press into place, then you can probably use the glass dish with no trouble. You will need some way to prevent the clay sticking to the dish, such as spraying the dish with WD40 or draping it with a sheet of newspaper before the clay goes on. Once you have your clay in place and pressed down onto the mold, you wait a bit for it to set up, then remove it. Since the glass is non-porous, it won't allow any drying through it. Note that whatever type of mold you are using, the clay has to be removed from any "inside" mold before it starts to shrink. For example, if you draped clay over a hump-mold bowl, shrinkage would cause the clay to crack.

With plaster, you may be able to skip using any release and just allow the plaster itself to draw water from the clay. (Sometimes dusting with talc is helpful, though.)

Of course, if you are talking about slip molding, you absolutely must have plaster to absorb water from the slip, or you'll never get it out of the mold.

Best regards,

Bob Masta dqatechATdaqartaDOTcom D A Q A R T A Data AcQuisition And Real-Time Analysis

Can I add to Bob's excellent advice that I have found cling-film to be a very good interface between a non-absorbent surface and clay, and it is easier to lay close to a plate or dish (inside and out) than newspaper.

Steve

I agree, I have used this sometimes too, though either paper or cling film do leave wrinkle marks in the clay, these can be smoothed out though. Annemarie

I have had good luck using all types of things as moulds but generally use a thin sheet of plastic (dry cleaning bag or even Sara wrap as a liner. I do stoneware and fire in the cone 6 range

-- Maplewoods

The clay's we call stoneware in NZ are usually different to the clays we fire to cone 6. Some call cone 6 firing midfire, as opposed to earthenware and stoneware. It is usually the fine white clays produced to mature well at the cone 6 range that are used. Interesting differences I guess. A

Hi Sam, for some of the classes I teach I make bisque moulds from thrown clay (slump and hump moulds) they are ideal for press moulding and there are none of the risks involed with plaster moulds;failing this the cling film trick works well.

'Just an additional quick note; if you want some nice textures try lining your press moulds with old lace doilies and the like. Andy