How to Make a Ceramic Deep Dish Mould

I want to design and create a range of ceramic deep dishes and ceramic platters so the first step is to make a plaster mould that I can use over and over again to make a consistent shaped ceramic dish. (By the way, the word is "mould" in England and "mold" in the USA. Since I live in England, we'll go with the English spelling.)

My first attempt at creating the plaster mould didn't go very well because I couldn't extract the clay form out of the dish I was using for the shape. The second time around I did two things differently, I used cling film and I let the clay dry a bit so it started to shrink and pull away.

Step one, apply a thin layer of vaseline on the deep dish form. I had thought that this in itself would be enough to have the clay form fall out of the deep dish mould, but the cling film really was needed too. Could my soapy liquid be used instead of vaseline? I don't know, I'll have to experiment. After lining the mould, I filled it with old clay that I keep around for mould making and not for any other use. I then let it sit for a day until the clay started to pull away from the sides as this made it easier to come out.

I then placed the upside down lump of clay on a piece of glass and smoothed it out. Take the time to make it even and smooth because this will form the negative of your mould.

Next build the plaster pouring box with wood sides and seal all seams with old clay so that liquid plaster won't seep out. Wash the entire inside surface with soapy liquid and now you are ready to pour in the liquid plaster. Pour in the liquid plaster and cover the entire clay lump. Let it dry for about 2

hours and then pull off the wood sides. Flip over your new plaster mould and remove the old clay and you now have a cavity that takes the form of your deep dish. It will take about 5 - 7 days for the new plaster mould to fully dry and be ready to use. This cavity can be used over and over again as a plaster form for ceramic deep dish pans.

Here's what some of my final (pre-glaze fired) baking dishes look like...