Once the clay is removed, replace the Lego piece you took out and add
another layer. You want the mold to be at least 1/2 inch thick above the
part.
To make sure the silicone does not stick to the bottom half of the
mold, you need to spray it with a Silicone Mold Release. If you don't,
you won't be able to separate the two halves.
Measure out some more rubber and add the catalyst. Stir it up
good and proceed with the degassing.
De-gassing your rubber. I transferred it to a clear
container and got some better pictures of the degassing stage this time.
You do not want to use the container that you originally mixed it in
because there will be some un-mixed rubber stuck to the sides of the
container. If you get any streaks of unmixed rubber in your mold
you may end up with some uncured, sticky spots.
You can see how it appears to boil. After a few minutes, it
will start to collapse as the bubbles pop.
Pour the top half of the mold starting from a low spot in the mold.
Once it creeps over the part you can pour it right on top.
