Question:

Would it melt styrofoam insulation board?

Answer:

It will not melt the styrofoam, and would be OK to apply, but the lacquer thinner generally used to control the consistency WILL melt the styrofoam. If applying to this type of material, it would be recommended to first apply a base coat without any lacquer thinner and little powder. You can then topcoat with moderate amounts of lacquer thinner if you want to add more powder component for higher build applications.