Step 7: Weigh Parts A and B into separate containers such as a clean bucket or quart cups (the same ones you have in your shop for your cup gun), then gently mix both parts together. There is a long working time, unlike marble resin. Be careful not to whip the mixture to prevent air bubbles. Unlike a marble matrix, there is no vibrating the mix or using an air release agent, so start filling in one corner and allow the liquid to flow out and fill from that one corner. Never dump silicone liquid over the original piece. Starting in one corner allows better air release from the liquid. Also, make sure the mold is on a level surface. Within 24 hours, the silicone matrix will harden and cure, then you may can your de-mold process.
Step 8: After the silicone hardens (20-24 hours depending on shop temperature), break down the frame walls and gently pull the frame back from the hardened silicone. Slowly pull back the silicone part from the mounted original part. There’s a lot of “play,” or flexibility, with this type of material.
Step 9: Slowly grab a corner of the silicone and begin to loosen it and peel it back from the original part. It’s very pliable. Gently pull the silicone mold over and off of the original part. Trim any excess silicone, and you now have a pattern that is an exact replica of your original part.
Step 10: With the new pattern in hand, you’re ready to make a custom part. The silicone used in TinSil ® 80-30 is specifically created to withstand the effects of polyester resins and gel coats. A silicone corbel mold is tricky to spray gel coat into to get an even 18-22 mils of thickness. We opted not to use gel coat for purposes of the demonstration. Brush in the gel coat or attempt to lightly spray it into the mold, depending on the complexity of the pattern. Back pour with catalyzed marble when the gel coat sets up or dries. Allow the marble to cure.
We made an exact replica of the original cheap foam part, but now it’s an engineered composite part!