My First Mold

After the silicon had cured I went around the edges with an Exacto knife and trimmed it to a clean edge. I then extended the underlying clay and created positive and negative registration marks to help the mother-mold securely align to it.

I then heated a small cup of Vaseline in a double-boil setup until it was soupy. I used a disposable brush to get in all of the nooks and crannys of the clay. I then used a second clean brush to remove excess Vaseline. I finally sprayed the silicon with a mold release agent produced by Smooth-On.

I then mixed up a small batch of Plasti Paste 2 and applied it to the back of the mold in order to create a mother mold.

As you can see, once cured the material becomes opaque unlike the freshly mixed material you see above.

I then had to figure out a way to release the clay from the piece of foam core I used to set it in place. Eventually I decided to cut a long groove out of the back in order to bend the sheet away from the mold. 

It worked like a charm. A second cut later and the board was easily removed. 

And oh my, the clay practically fell out of the mold.

It just peeled...

....right away.

And here I am left with a successful looking mold ready to be hit with the other half!