Resin Addict Forum

Have been pouring epoxy into tin cure silicone molds, and getting about 10 molds before the silicone starts to let go in the small features, less than about a half mm. If I try for 20 molds, pieces of mold about 1mm start letting go.

Anyone have basic recommendations for extending the number of molds?

You're using pretty much the worst possible combination of materials! Try:

- Polyurethane resin (if possible)
- Platinum cure silicone
- Thick coating of release agent

Depending on the detail depth I work on an expected 30-40 pulls from a mould.

Thanks. Have to stick with epoxy, but will try platinum molds, and a silicone agent.

Is heating good, to speed up the cure and demold, or is slower overnight cure better, for making the mold last longer?

I would have thought that heat would be worse for the mould.

Also, have a look into silicone oils. I've heard of some people applying it to the mould and baking to rejuvenate the silicone, but have never tried it myself.

Silicone oil is different from agent? I have silicone spray agent on the way, with the platinum.

I would like to find out about the heat. I don't degas, so when heating after pouring, the bubbles don't have time to pop.

Yeah, silicone oil is different to silicone release agent. You only treat the mould with it occasionally, not every cast.

If you plan on painting, get wax release, not silicone release.

No painting.

We've been using the silicone release and it has helped a lot. Spray the mold before each pour.