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Silicone mold life

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Silicone mold life

Postby RAuser » Wed Jun 29, 2016 1:42 pm

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?
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Re: Silicone mold life

Postby mangozac » Thu Jun 30, 2016 7:28 am

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.
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Re: Silicone mold life

Postby RAuser » Thu Jun 30, 2016 7:36 am

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?
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Re: Silicone mold life

Postby mangozac » Thu Jun 30, 2016 4:49 pm

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.
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Re: Silicone mold life

Postby RAuser » Fri Jul 01, 2016 1:34 pm

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.
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Re: Silicone mold life

Postby mangozac » Mon Jul 04, 2016 7:26 am

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

Postby Fleafa » Tue Jul 05, 2016 7:31 pm

If you plan on painting, get wax release, not silicone release.
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Re: Silicone mold life

Postby RAuser » Thu Aug 04, 2016 1:46 pm

No painting.

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