Platinum silicone not curing, is epoxy or acrylic paint to blame?
I've done some molding and casting with platinum cure silicone, but for the first time the curing has failed with the surface remaining sticky goop. This is the first time I've used platinum cure silicone on epoxy clay painted with acrylic paints, which leads me to assume one or the other is to blame. But which one?
The epoxy clay was Apoxie Sculpt, and the sculpture is roughly a year old, absolutely totally cured. It was also fully painted using Vallejo acrylics, so there would be no direct contact between the epoxy and the silicone. That makes me suspect the paint rather than the epoxy, even though I haven't had this problem with painted plastic.
What I do know is the silicone itself hasn't gone bad, because there was some left over I used to make a skin texture mold from an old face cast. It cured well within the expected time, as did the residue in the mixing cup.