Dry slowly with a plastic bag hung loosely over the sculpture. Thinner areas such as ankles and arms should be covered with a dry cleaning bag or Saran wrap, to allow the thick areas to dry at the same rate as these thinner areas. Wait until the clay is “leather hard”, that is, hard enough to handle without leaving a finger print but still damp enough to sculpt.
Using pillows, position the piece to access the bottom of a seated or reclining pose. Hollow out the piece with something like a spoon or sculpture rake tool so that the wall is about 1 inch thick. OR you can cut the piece in half horizontally or vertically and remove the clay. Then put together using very wet clay (called Slip) as "glue", scoring both edges of the piece for the wet clay to grab on to. Let it dry out slowly and thoroughly using the same technique explained in the first paragraph.
A patina can be created in several ways. Japan colors (powdered pigment) can be added to the initial shellac layer. And or combined with wax and denatured alchol in subsequent layers. This creates multiple coloring and a feeling of depth to the patina. You can also use clear or tinted wax or shoe polish to create dark areas. Buff only if you want a shine.
Materials can be found at Home Depot:
cheap paint brush suitable for the size of your piece
Japan colors (powdered pigment) are in Art stores
saran wrap to cover the jar
news paper to protect surfaces
pillow and protective covering
Pour out about 1/4 cup of the shellac first and add the denatured alcohol. Mix the shellac and denatured alcohol until the liquid is water thin, about 50/50. The proportions will depend on the air temperature and the humidity. Use saran wrap to cover the jar in between coats. A jar lid will stick.
“Paint” the mixture on the piece, going inside the hollowed-out area as far as possible to seal the surface completely. Drying time can be from 15 minutes to an hour depending on the weather. Coat 3 to 5 times.
The concept is to allow the shellac to penetrate the clay and fill in the pores. It may take several layers of shellac to fill the pores up to the surface. Each situation is different and must be gauged by eye.