I recently completed a course in figure sculpture. Instead of the typical stoneware clay I use for ceramics, we used oil-based clay for the sculpture. After creating the sculpture in oil-based clay, one normally creates a mold and then either creates bronze or resin casts of the sculpture from the mold. I thought I would test mold-making out.
To simplify matters, I created another sculpture, this time of a head instead of the full human figure. (Creating a mold of the human figure is more complicated: open spaces between the arms and torso and also between the legs need to be filled in.) To sculpt the head, I again used an oil-based clay. I left some details around they eyes unfinished to the mold would come apart more easily.
When the head was ready, I created a silicon mold of the entire piece, mixing and then painting multiple layers of Smooth-On’s Rebound 25 formula directly onto the oil-based clay.
After that, I encased the silicone inner mold with a plaster mold to form a hard shell.
After the silicon and caster molds hardened, I stuffed the clay I typically use for ceramics into the mold. You’ll see that I set up the mold to open into 2 parts so I can access the interior and make 2 cast parts which I then need to fuse together.
Here’s a photo of the two cast parts fused together (before firing), including some details to the eyes that I added.
Photos of the finished, fired head are at the top of this article and below (different angles).
The process worked well enough, but honestly it was a lot of work creating that mold. And it was messy. I’m not sure how often I would want to cast additional copies of this head. I might be inclined to cast multiple sculptures of a figural work (such as the original sculpture we worked on in the class), and in that case creating a mold might make sense, although again creating a mold for this piece would be more complex. So I’m not certain how often I will use this technique, although it was interesting to test it out.