I have been making slab platters for years by slab rolling a large piece of clay draping it over my bisqued hump mold which i made years ago.
Compressing a slab ceramics.
To do so evenly roll out your clay to the thickness you desire using rolling clay slab sticks 3 8 inch is a good starting point.
Compressing the slabs together she repeats her refining and smoothing process 8.
Then take a straight needle tool and holding it flat against the bat surface press inward until the needle tool can be felt dragging on the bisque mold.
The second type of mold is a bisque mold which is super easy to make yourself.
Before attaching the bottom piece of clay to the form in the mold van hoey stamps the bottom of the slab with her chop potter s mark and places the slab into the mold face down this way impressing the stamp won t distort the final form.
When the foot is finished trim the excess slab to about inch away from the rim of the bisque mold 13 and compress this clay into a nice rounded edge above where the clay meets the bat.
If the clay it is too thick it will not fit under the roller.
Preparing and compressing the slab.
To compress the clay slightly you can use a rolling pin or your hand.
Before you use the slab roller make sure that the clay slab is no more than three or four times thicker than the desired result.
Use a template or a bat to cut a circle out of the slab.
Drape it over an inverted footless bowl that was bisque fired to two or three cones lower than the clay body s maturity see 1.