PDMS curing issues when using 3D print as a mold


I would like to use 3D prints as molds for a PDMS replication. Unfortunately, the surface of PDMS in contact with the mold does not polymerize properly and stay sticky.
The real problem is that I have to bond this PDMS piece on another one (by plasma activation) and it does not work when the PDMS is mold with a 3D print.
So does anybody has encounter the same problem and has a solution?
Is it possible that some components of the resin get into the PMDS and prevent PDMS bonding?

Just speaking as an old-school propmaker, not all silicones are alike. Which begs the question, is PDMS tin-cure or platinum-cure? Judging from the complaint, it sounds like the latter. My only suggestion is if your project is imprecise enough to allow it, spray the 3D print with a coat of lacquer or similar protective coating. Going next-level, if you have the facilities for it, mold and cast a copy of your 3D print in a material that is agreeable to PDMS. Just watch for shrinkage factors that may affect your precision.


I think it’s platinum cure, might be similar to Smooth-On’s Solaris

I haven’t tried theirs yet, waiting to get enough dead tanks to make it worth while. They have a sample kit for under $80 that I think you could do about 10 tanks with.

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