Surface prepping sculpted foam?

[zorg]

gonna be getting some blue sculpting foam shortly (well its actually floor insulation)

my question is, say i have cut and sanded it to the required shape, how do i go about preparing the surface for molding?

does it get coated in something?

what tips you got?

thanks

-z

 

[the_batdemon]

Depends on what you're molding with. Stone or silicone, I don't see a need to use a protective coating. With Fiberglass, I'd use latex house paint or wood glue as a barrier between the foam and the resin solvents.

 

[zorg]

sorry i should have said to make silicone molds from. i don't want to put the silicone directly onto the foam. i would like to put a layer of something on it so i can sand it really smooth before molding.

but what?


-z

 

[the_batdemon]

I've had success getting wood glue pretty smooth. Also, dry wall sanding cloth gets the blue foam smooth.

 

[zorg]

i was thinking about applying a layer(s) of polyurethane resin over the top, but don't know if that would attack the foam or not :unsure

or even a skin of bondo then sanded down.

-z

 

[the_batdemon]

The resin will attack the foam, without a barrier. Try the latex paint, it's simple and cheap.

 

[zorg]

i would like to add extra detailing to the outer layer such as scribing lines etc.. so glue or latex paint would not work for me.

 

[the_batdemon]

The latex paint is just to act as a barrier between the foam and the resin. you could also use joint compound. This won't affect the foam.

 

[exoray]

If you want a hard shell to continue detailing...

Google "Foam Coat" there are a few products out there... There is the more plaster like "Rosco Foamcoat" and the the acrylic resin called "Steve's Foam Coat"

 

[00MrNotWrong00]

I like "Gripper Primer" , not cheap but works very well , and it's a sealant , will not attack your foam , and I have not had a problem with it peeling of the foam.

What have made ? I love foam carving and it's been around for some time but it always seems so new. There are still no rules or procedures , and no reefer-ance material.

Some one should write a how to book or something.

 

[fettster]

I used an autobody spray filler to seal urethane foam, it's the stuff in a tin that needs to be put through a gun but you can paint it on with a brush and sand it. I have also used straight gel coat

 

[Dung0beetle]

White (pva) glue or wood glue works great to provide a protective layer. (learned the hard way after hours of carving some foam just to end up with a goopy mess after trying to cover it in resin)

 

[JBReplicas]

I used Grey Gesso on a sculpt I did many moons ago, you paint it on in about 4 thin layers and you can sand it, however it does crack if mishandled i.e picked up by the girlfriend and 'moved'

 

[morpheus13]

You can also try acrylic medium. It cures VERY hard.

 

[BornKilr]

Batdemon mentioned joint compound. It works great and easily sands to a slick finish.

 

[zorg]

a lot of good advice guys thank you,

nice to read what worked for people and what didn't

i had though on that joint compound filler stuff but the stuff i have use in my home at least looks like it might be a bit fragile? (easily marked)

i think there was a chap on here who used it to skim the outer shape of a robot he was building.

it looked like a fast and easy (to sand) way of doing large areas.

anyway, anyone else like to throw their hat into the ring?

thanks again

-z

 

[zorg]

The latex paint is just to act as a barrier between the foam and the resin. you could also use joint compound. This won't affect the foam.

gottcha :thumbsup

 

[morpheus13]

Joint compound is cheap and works fine but is fragile in the end. You can definitely use it, you just have to be more careful with it. Acrylic medium goes on just like joint compound but cures to a stone-like hardness and finish. Its much more expensive and harder to work after hardening but I've dropped pieces 5 feet onto a concrete floor with no damage. Another benefit is that bondo grabs onto it really well for final detail sanding. I seemed to have a lot of trouble with bondo on joint compound.

 

[zorg]

i'm in the u.k. do you have any links or brand names of this stuff, i'm not familiar with it.

:thumbsup


-z

 

[zorg]

i'm in the u.k. do you have any links or brand names of the stuff you used, i'm not familiar with it.

:thumbsup


-z