Demolding the first half. I made a predicable error and didn't have enough silicone Oomoo 30 to create both halves of the mold so I decided to make one half for now. There is an iphone app for calculating how much you need - should have checked PLUS I had a small leak in the plastelina block so I lost about 15% of the silicone to the interior of the clay blocking.
I used plastelina to displace as much silicone as I could knowing that in the end I'm gonna have to wrangle with that when I cast - having each half made of nice solid silicone would have been great or even if I had used plaster as a support shell (I'm watching vids and tutorials as I go so I didn't have that technology when I started using plastelina.)
Overall I suspect that for this kind of figure - pourable silicone might not be the way to go. Brushable (thick paste) silicone like Rebound 25 with a plaster support shell is what I'll try next.
Building the box for the pourable silicone and using plastelina to block off the front - I might have gotten away with a flat pour but since I didn't have a good sense of how forgiving the Oomoo is when demolding an underhang like the hands would have created I tried it this way. Cosmonaut in his coffin. My workspace on the back porch and after using sealant and release agent, pouring the silicone so it is 1/2 inch over the highest point of the figure. Overnight curing and then demolding. You can see the plastelina I used to block off the bottom. The surface of the mold is VERY ROUGH, I guess that is ok but still pretty ugly compared to the nice clean mold halves I was dreaming of. This is due to the surface of the plastelina used to block off the front side.
Concept artist and creature designer.