Blue foam as a master?

[Lonnie Sweet]

Hi all, can the blue insulating foam you buy at home depot be used as a master for resin casting? Will it deform or any other problems? It's a small piece about 2-3 inches across.

[vaderman]

You can use it to sculpt a master. Make sure you seal it and then put a skin layer of of some kind. I use Aves Apoxie Sculpt. You can try Bondo Body filler, but I am not sure how it would react to the foam. Don't use the spot putty. That will eat the foam. You may need to test the bondo as well. You will need to mold it with RTV Silicone. Once you have the mold, you can make resin casts.

Scott

[Antenociti]

depending on the density of the foam it will deform if you pressure cast the mould/master... the higher density foams, 52kg/m3 and higher are usually fine for up to 60psi or so, any higher pressure and they deform.

the common craft foams and insulation foams are only 25-32kg/m3 and can deform at pressures as low as 30psi.

[Rogviler]

Pretty much anything in the body filler family will eat pink/blue foam as well as the beaded styrofoam, just FYI. Some people have had luck with mixing it so it'll cure really fast, like almost instantly, but that's got a whole other set of issues...

The only thing you can use like that would be epoxy glues. When in doubt, test it.

Other than that and the points mentioned above, you shouldn't have a problem.

-Rog

[Mark Yungblut]

Roll out yourself some Aves or magicsculpt and skin your foam with that. Look for an article cover this and other Expoxy goodness coming soon. until then ping joe Brown he has the technique mastered. Which is why we co-teach the class at Wonderfest.

[Migmaker]

just seal the foam with latex house paint then got to town with any thing you want to smooth it out, bondo fiberglass, whatever you wish
Will