What Epoxy Resin that works with Smooth-on?

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Kaptainkirk

New Member
Hello All!

Im currently working on making some copies and I have the mold made out of Rebound 25 which i've never had issues with.
But im trying to cast in a clear epoxy resin. The epoxy resin I bought was from hobby lower and cheap, I figured it would work fine, but the epoxy never wants to cure. I froze it and was able to remove it from the mold but once it cooled they just kind of flattened out like melted gummy bears.
Does anyone have experience or know of a brand that works with smooth-on silicone rubbers. I know they have the crystal clear, but I was seeing if there were some cheaper off brand options what would work just fine.
Or do the two not mix? I.e. silicone rubbers and epoxy resins.
 

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8 perf

Sr Member
From my experience, its best to use compatible products from the same manufacturer to get good results. I have never had good results using clear casting resin from any discount/ craft store in one of my silicone molds. Does exactly what yours did.
Id say use one of Smooth-On's urethane resins for a better result. I know they have a few types that are clear and can be tinted as well.
 

animator

Well-Known Member
Smooth-On has a customer support phone number. They have been great about answering my questions and suggesting products and techniques. Talking with them first has saved me from mistakes that would have wasted a lot of very expensive materials.

The phone number is on their website, and I highly recommend it.
 

udog

Active Member
Not sure the problem is the silicone mold nor a compatibility between manufacturers. Looks more like there is a problem with the resin you are using. Most resins (in general, some exceptions, but wouldn´t say epoxy is one) should be ok with a silicone mold in general terms and conditions.
 

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Duncanator

Sr Member
Epoxy shouldn't have a problem with a silicone mold. I agree with udog that the issue is probably bad epoxy resin.

One thing you mentioned was that you "froze" the epoxy to remove it. Not sure what you meant by that, but I have found that if epoxy is subjected to cold before it has completely cured, that it kills the catalytic reaction - and then never completes its curing process.
 

udog

Active Member
One thing you mentioned was that you "froze" the epoxy to remove it. Not sure what you meant by that, but I have found that if epoxy is subjected to cold before it has completely cured, that it kills the catalytic reaction - and then never completes its curing process.
Yes, that´s what I thought too. Actually frozen epoxy+fiberglass (prepeg) is used to laminate and reactivated when put in an oven to complete the reaction. It´s a common method used for carbon fiber laminating (vacuum bag compactation).
Not sure if Kaptainkirk means he froze it to remove uncured epoxy from the silicone mold or that he froze it just to demold. Which could be the culprit.
 

R2Origins

New Member
What are you using to release the Epoxy from the Silicone mold with? Any Epoxy should peel right out of a platinum silicone no problem.
EpoxAcast690 is one of my favorites, get a trial size, about $30. Crystal clear and meant for these applications, make sure you have a scale for weighing out, super particular.
Hope this helps a little.
 

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