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Permalink Reply by Greyguy on December 11, 2015 at 8:06am

I have cast tin silicone in tin molds you should not have any problems in additional cure silicones but do a test

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Permalink Reply by Tim Daniel on December 12, 2015 at 2:25am

Cheers Greyguy, that sounds promising.

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Permalink Reply by John Douglass on December 15, 2015 at 1:41pm

Be very careful with that.  Platinum silicones are very tricky and have many inhibition problems including being cast against tin base silicones.  It will probably not work but you could run a small test to see for sure.  My experience is that the platinum will have an uncured surface where it touches the tin rubber.

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Permalink Reply by Tim Daniel on December 15, 2015 at 2:32pm

Cheers John. I was thinking, like Greyguy said of trying out tin silicone casting in a tin silicone mold. Very good to know that platinum and tin silicones are definitely not compatible.

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Permalink Reply by StopmoNick on December 15, 2015 at 5:35pm

I've been casting platinum cure silicone puppet bodies in fibreglass (polyester resin, though epoxy resin would work just as well) moulds.  I really don't see the point in having a flexible silicone mould to cast a flexible silicone puppet in.  

Although, if your original sculpt was hard, like a baked Sculpey, it does make sense to make the mould flexible so you can get it off.   I got a small batch of Adam Beane's CX5 sculpting material to try out, and it's hard as a rock unless it's too hot to touch, so silicone is probably what I'd have to use if I wanted to make mould from it. 

You seem to have success with platsil in platsil - I presume you are using some kind of mould release?  Maybe the mould release would also avoid curing problems if casting in a tin cure mould?  

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Permalink Reply by Greyguy on December 16, 2015 at 5:09am

Ya you don't want to pour plat silicone in tin mold but plat in plat would work with a release and tin in plat would work and tin in tin :)

An advantage to a soft mold is what Nick said if you happen to have to make a mold off a hard sculpture. Another advantage is if you make a mold with a hard durometer silicone and you are careful making a clean tight seam and you cast a skin in that mold you can end up with a almost nonexistent bit of flashing because when the mold is put together with a rubber band the mold can really squish together (ever so slightly) and make for the tightest seam

Also you need to make a flashing edge in the mold so excess silicone has a place to go

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Permalink Reply by Tim Daniel on December 16, 2015 at 10:04am

Awesome info, thanks guys. I just tried it out because I got some testing materials to try it with but it seems to work ok. Absolutely essential, like Nick said, is mold release. (I use Mann ease release 200 and petroleum jelly) like Greyguy mentioned, one big advantage also seems to be that with a clean seam, I can put a support board on either side of the mold and tighten it a bit in my bench vice. Just enough to squeeze it tighter than it would normally sit, and the result which can be seen in the picture above is almost invisible flashing without creating a flashing edge inside the mold.

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Permalink Reply by Greyguy on December 16, 2015 at 10:52am

dawn soap is something I was told about and heard about for years. will be trying it on the next project

Make sure you do test !!        most important

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Permalink Reply by Tim Daniel on December 20, 2015 at 10:07pm

I have been testing the method out and petroleum jelly seems to be doing the trick with various abrasive bits.

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Permalink Reply by Greyguy on December 21, 2015 at 3:39am

Nice to hear keep it up

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Permalink Reply by Jason Whetzell on October 1, 2016 at 6:01pm

Can I ask you what you use exactly?  Should any two part resin work for this?  My monster clay gets stuck in the ultracal no matter how much crystal clear I use and it's annoying.

StopmoNick said:

I've been casting platinum cure silicone puppet bodies in fibreglass (polyester resin, though epoxy resin would work just as well) moulds.  I really don't see the point in having a flexible silicone mould to cast a flexible silicone puppet in.  

Although, if your original sculpt was hard, like a baked Sculpey, it does make sense to make the mould flexible so you can get it off.   I got a small batch of Adam Beane's CX5 sculpting material to try out, and it's hard as a rock unless it's too hot to touch, so silicone is probably what I'd have to use if I wanted to make mould from it. 

You seem to have success with platsil in platsil - I presume you are using some kind of mould release?  Maybe the mould release would also avoid curing problems if casting in a tin cure mould?  

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