Mold Making: Two Part Silicone Mold

Step 4 Mix and pour your silicone

Silicone is a great molding material because of its natural tendency to not stick to things. This makes it ideal for casting a wide variety of things from plastics to plaster. However, it does love to stick to itself. If you don't make sure the mold is properly sealed in between castings, you'll find yourself with a big block of silicone with an action figure prize inside. I'm serious.

I recommend you use a digital scale to measure out your materials. I try to gauge the volume of my mold by some simple geometry. Always mix a little more than you think the mold will actually take to fill. It's very difficult to mix up a new batch of material on the fly when this happens. Also, before casting, inspect your entire mold to make sure that there are no possible holes or leaks. Even a tiny pinhole leak in your mold could mean you find a pool of cured silicone on your rug and a lightly silicone glazed part in your mold when you come back to check it the next morning.

Mix as per the manufacturer's instructions, and pour in a high, thin, even stream to eliminate air bubbles.