Coating styrofoam?

[PropReplicator2]

So I've got a structure I've recently built from foam board and was wondering what you guys use to coat it to add some durability? I've used a fast setting resin like onyx fast and it worked great but was extremely thin and cracks after too much sanding. I've heard a million things from plasti-dip to watered down Elmer's glue. The end goal is to have a sandable surface that can be primed, painted, and molded.

 

[Moviefreak]

This works well...

 

[PropReplicator2]

This works well...

View attachment 1358992

I'll give it a shot, ive got plenty of it at the house.. I was looking for something that could sort of soak into the foam to apply a layer of rigidness rather than a thin layer of hardness over the foam like this or bondo would.

 

[Moviefreak]

I'll give it a shot, ive got plenty of it at the house.. I was looking for something that could sort of soak into the foam to apply a layer of rigidness rather than a thin layer of hardness over the foam like this or bondo would.

Maybe do the watered down Elmer's Glue to soak in, or Gesso to soak in. Once dry, add this Bondo layer on that for added rigidness? Just a thought.

 

[wtyler3]

I use foamcoat almost exclusively now. it is the best filler stuff I have every used and I have tried everything out there. Hardens but easy to sand, can be sculpted, it is water soluble and non toxic.

Buy FoamCoat | Cosplayshop.be

It is made for your exact need, but I use it on everything. They will ship I think up to 4 bottles.

 

[TazMan2000]

Aliphatic resin or Carpenter's Glue will work and probably available everywhere.
Either hang your foam object from a place where it won't show, or stick it on a coat hanger to ensure that after your coat your foam, it doesn't lie down on a face where it would bond to something and ruin the coating.
Use a wide brush so you can coat your object with only a few strokes. Re-apply as needed. If applied correctly the glue will smoothen itself out. Several light coats are better than thick ones. After its dry, start sanding and see where you need to fill.

TazMan2000