I'm wondering about the use of sodium silicate in slip casting. Is it to help release the firm slip from the mold?
Here's my problem. I have some plaster plate hump molds that if I use slabbed clay draped and formed, even with Mea's help with cornstarch(which works very well), slabs can retain some memory and rims warp slightly .
What I would like to do is create a mud that can be jiggered onto a hump plate mold, yet release easily on drying.
This is where I thought sodium silicate might come into the process, allowing the mold to release the clay.
I seem to remember a potter using this method but that was 30 yrs ago and is no longer around, so I have no idea if he used sodium silicate or any other release agent in the mud or on the mold.
The clay, as I remember, was firm enough to stay without puddling out or releasing any water as is sat and jiggered smoothy over the mold.
I feel I'm missing a key step or ingredient to make this work