I am trying a new experiment making a mold from porcelain. . The technical challenge is getting a detailed mold from the bisque, which is dry and porous. So I am trying to make a mold using wet clay. I thought I would share step by step as I am working on this experiment.
below: the carvings themselves are porcelain, carved while wet, leatherhard, and bone dry. Each one took about 3-4 hours to carve. They are flat on the backs and about 1 1/2"w by 2" high. They have been bisque fired to cone 06
above: pushing up the walls around the carving. I tried to press down on the carving as I did the edges, so it didn't shift.above: All the sides pressed up and smoothed out evenly. The carving is then carefully pulled out of the clay using the handle, trying to pull straight up and not distort the surface underneath.
above: on the right, the carving
below: a small ball of clay is rolled into a smooth ball and flattened to about the size that will fill the mold. This comes with some experience pressing the mold a few times. It is better to have a little too large of a piece of clay. The most important thing is that the clay should be soft and smooth where is is going into the mold.
below: the clay is pressed into the mold firmly, near the center. Great care should be taken not to let the clay shift once it hits the mold, or the design will be doubled. The clay can then be pressed out into the corners and sides.
below: Any excess clay is scraped along the edges. The back side of the clay is smoothed out as much as possible
below: The back is stamped with my chopmark. The clay is left in the mold for a little while to stiffen up. This is crucial timing...the clay should be stiff enough so it comes out of the mold easily and without distorting, but also not too stiff so that the holes can be made. It takes practice.
below: after the clay is removed, the holes should be made. I use a soldering pick for most of my holes. The pick is pressed from front to back the point can be felt on my finger beneath. Then the pick is removed and pressed from back to front, making a clean hole. ((edit: since I posted this originally, I use a hollow coffee stirrer straw...it works better for me and avoids some of the cracking around the hole, as seen in the picture below))
below: The holes are flared out a bit with a spout tool (or a pencil or other sharp flared tool). The piece is left to dry.
Once dried, there may be some clean up needed. Notice the edges in the picture above. The edges are sharp and ragged. This will need to be scraped with a sharp knife and then smoothed with a damp cloth for a soft finish. The pieces are then bisque fired, glazed, and then glaze fired. Maybe another tutorial for another day...
Here are some of the finished pieces: