hardening foam

[larryluftwaffe]

Sorry if this question has been asked before, but does anybody know a good way to harden EVA foam?
I'm not sure using a bondo resin would work with closed cell foam.
I'm just using it to make some armor plates for a set of boots, and I'm trying to find a way to make it all stiff (er)

 

[jordandau]

You'd have to coat the foam in something like PVA glue before bondo. Bondo would sort of melt it.

 

[Stony Props]

Epsilon (smooth on product) may be the way to go. It can leave your piece whit a bit of a hammered metal look to it.

 

[SMP Designs]

The short answer is: "you kinda can't."

The longer answer depends on the foam and thickness you're using. The thing is, if you just seal and bondo (or use any resin) the foam, it will make a nice hard surface, but if you knock it against anything, the fragile resin will snap and crack and there's virtually no way to fix that.

If you're using thin (2mm) foam, you can Worbla it and that will give it a lot more structure to support the resin with (less) danger of snapping the resin. Another option, if you get really clean cuts and very clean base build in the foam, is to use a heat gun to shape it, then use Plasti-Dip directly on the foam to give it a nice smooth surface. The hitch there is to use the brush on Plasti-Dip, never the spray. They have the same name, but they do not cure the same. A few coats will help give the foam pieces more structure an you can prime and paint it with ease.

Another tip with PD, keep a small bowl of Naphtha thinner nearby and you can dip your brush in that if the PD starts to get goopy or you want to brush over the piece while it's still wet to smooth it out more. While you will see some brush-strokes on the piece while it's still wet, the PD will self correct as it cures and smooth out.

 

[charades]

If you're using the thin craft foam EVA, you can hot glue thin styrene to it and heat form. This is the premiere tutorial I've seen: http://amethyst-angel.com/armortutorial/armormaking_construction.html

Really depends on what kind of angles and shapes you'll be making. I can see this being tough to do with some really complex edges and lines, but a great way to do small and/or smooth surfaced pieces

 

[larryluftwaffe]

You guys are rad. I've been wrapping my head around this for a bit, I'll see what results I get. Thanks!

 

[SDGlyph]

James Bruton at XRobots.co.uk put up a couple of experiments in coating foam with PVA (to seal it) and casting resin (to harden it) a while back. There's a video too.

 

[Malzabear]

You can harden foam with a lot of different things.

I know some people like to use worbla.. Which is a bit pricey. It's thermoplastic that can be heated, and formed.. And when it's cool, it's stiff again.

Another really popular way to seal it is with wood glue. It's surprisingly cheap and effective. It takes paint well. But you have to wait for the coats to dry COMPLETELY before putting a new one on, otherwise it could screw it up.

 

[larryluftwaffe]

Wood glue.....hmmmm that never would have crossed my mind.

 

[Hermes]

If I may interject as well, Styrofoam glue also works wonders. It is soluble in alcohol, and therefore, not water-soluble like PVA , which is a plus if you happen to be caught in the rain or something. I usually dilute it 50-50% ISH. It means, I have NO consistence at all, I go by the feel of the mix. It auto corrects brushstrokes to a degree, like Plastidip, and alcohol-based as it is, it dries pretty quick , and leaves a paintable surface.

 

[larryluftwaffe]

If I may interject as well, Styrofoam glue also works wonders. It is soluble in alcohol, and therefore, not water-soluble like PVA , which is a plus if you happen to be caught in the rain or something. I usually dilute it 50-50% ISH. It means, I have NO consistence at all, I go by the feel of the mix. It auto corrects brushstrokes to a degree, like Plastidip, and alcohol-based as it is, it dries pretty quick , and leaves a paintable surface.

Where can I get styrofoam clue?

 

[TurboTrey03]

http://www.therpf.com/f24/foam-finishing-question-thread-179203/

Some great stuff in here..