What is the best hard coat for Pink Isolation foam.

I am making a somewhat large prop out of pink insulation foam and i want to give it a smooth hard coat. I know most things melt insulation foam so what is the best way to get a nice even hard coat so it takes paint well?

Morning, it would depend on a few things. I used Hot Wire Foam Factory hard coat products in my theater. But that leave a very rough stone like texture, and if you're handling the prop, it probably wouldn't hold up. The other product I almost used, was Styrospray 1000. It's a thin layer of plastic that coats the prop and it appears very robust. It's a bit in the pricy side though, so a large prop may be expensive. It can be painted on or sprayed on if I'm not mistaken? There are some reviews of it on the forum.

What are you making exactly?

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You can also fiberglass over it if you properly prepare the foam, otherwise it would definitely melt it.

I've used Smooth-On's Epsilon product for that. A couple of coats makes it really solid.

Easy Flow 120 polyurethane resin shouldn't melt the foam, haven't handled it to see the finish in person yet though.

You can lay fibreglass if you use laminating epoxy instead of polyester. The downside is that it can be hard to get a properly smooth surface with fibreglass on the outside of a prop.

You could also make your own coating out of laminating epoxy and fillers. I would use colloidal silica and microfibres for strength but that would not sand well. If I would want a sandable surface, I would add a second coat with epoxy that has talcum powder (baby powder) instead of microfibres. You could find it in stores for boat repair. There might be smaller repair kits so that you wouldn't have to buy large amounts.

Urethane resin has worked for lots of people. I have had bad luck with one type though (Esprit Composites), that melted styrofoam ... and the plastic cup I tried to mix it in.

There are several older threads on this subject also that you could look up and read.