How to make molds of your polymer clay sculptures and use them to cast hydrostone sculptures.
WHAT YOU NEED TO BUY:
In this "how to make a mold" tutorial I will be showing you how to make molds of a sculpture you have made in polymer clay. We will be using Rebound 25 which is a super flexible brush on silicone rubber that is made from a 2 part compound you mix together. We will then use a strong gypsum plaster called Hydrostone to make the cast. I will also use Stoner- Rapid Release which is a releasing agent in spray form. This prevents prevents your sculpture or the cast from sticking to the mold.
This tutorial works best for sculptures that are very contained with no protruding limbs.
Here I have sculpted a fairly contained sculpture of a mushroom man. Notice that there are no gaps between his arms and his body and there are no thin limbs stretched away from his body.
There are undercuts but it doesn't matter in this instance because the product we are using is very stretchy, so we will still be able to remove the cast from the mold.
You will need some thick, double-walled cardboard, plastic or something else that is strong enough to hold in the silicone whilst your mold sets. You will also need scissors and sticky-tape to assemble it.
Assemble a box (with no lid) just big enough to house your polymer clay sculpture. Be sure that is it fairly solid as you don't want it coming apart when you pour the silicone.
Now you will need to seal the box so that it is water tight for your mold (or silicone tight in this case). A hot glue gun works well but you can also use clear tacky fabric glue if you don't have one. Carefully work the glue into all the edges of the box making sure that every edge has a good seal.
Place your sculpture inside the box to ensure it fits perfectly. Notice that there is at least 1 centimetre of space around the sculpture. Of course you don't want to make the box too much bigger than the sculpture or you will simply waste your silicone. In some cases making a round container saves on space.