Once the first layer of silicon has cured, I pour a supporting mother mold of plaster. This step adds strength and saves on silicon. I remove the clay and get ready to pour the other half. To prep the first layer of silicon, I brush a mold release on it. In this case I've used petroleum jelly. I just apply it to the cured silicon, it's not neccesary to put it on the wax because the silicon won't stick to that.

You'll notice the little registration "nipples" (for lack of a better name) in each corner. These were made in the clay with a pencil before the first silicon pour.