Mold Making: Two Part Silicone Mold

Step 6 Molding: Complete

After the second silicone piece has cured, you're done with the mold. You can take your master out and inspect the mold. Now you're ready to clap it back together and cast your final parts. I usually hold molds together with rubber bands wrapped tightly enough around the mold to keep it together without distorting it. I'll use a bucket or something similar to hold it in the right position for casting.

This kind of mold is perfect for a wide range of liquid casting agents, from hot wax, to plastics, to resins, to plaster. Remember a few key factors:

• Each molding material has a different cure time, viscosity, and surface tension. Some of these materials are prone to capturing bubbles in the mold. To prevent this, make sure to read up on how to prep the mold, whether it's adding talc, or a release agent, to get the best quality casting you can.
• Learn what the mold tends to do, and make procedures to correct the errors. I found that this mold tended to catch bubbles in the little spheres that stick out from the base. I found that by shaking the mold, and poking at the bubbles with a small rod, I could get a flawless casting.
• You can make multiples of this mold by repeating step five over and over again. Professionals tend to make a plastic or silicone copy of their part just for this purpose, so they can duplicate as many molds as necessary without damaging the master.
• Recycle your scrap silicone. Since silicone is so eager to stick to silicone, it makes sense to extend your materials by mixing in chunks of cured scrap silicone with large castings. It saves a lot of material. You can also cast excess silicone into sheets in a loaf pan or muffin tins to use as mixing boards. They make great palettes as paint and epoxy won't stick to them.

For video tutorials on mold making, visit Freeman Mold Making and Casting Supply. There is a great tutorial on a more complex molding technique on ConceptArt. You can also check smooth-on.com for information on various molding materials and suppliers.