Diluting silicone with Naphta substitute: what to use?

This is a really poor substitute for a proper casting formulation. This molding material will damage many surfaces, the resulting molds will be fragile, and will shrink significantly over time. I also seriously doubt that pound-by-pound, it's any cheaper. And you wouldn't be able to pour layers of any serious thickness, because the material won't set.

I bet there are distributors in your country that can sell you gallon quantities of silicones. They are so common in artistic and small-scale commercial work that I seriously doubt it's impossible. They may have no online presence and you might have to give them a call, though.

That said, you can use xylene, toluene, or ethyl acetate (the main component of many types of nail polish removers - but note that acetone won't work). Mineral spirits would work, although they evaporate very slowly. Kerosene likely has the same problem.

/r/ResinCasting Thread