I have made a bunch of molds of shells with hydroperm. My question is simple …do I need to put primer on these molds before using them. I can find no other instructions other than to dry the molds at 300 degrees.
While I’m a new fuser and have not used hydroperm molds, I do have info that may help. In Brad Walker’s book “Contemporary Warm Glass” (p48), he describes 2 types of gypsum cement molds: hydroperm and hydrocal. In his description he writes: ” By contrast, gypsum cements do not need kiln washing. They are also able to pick up more detail than the other kinds of cements.” Good luck -your project sounds like fun.