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I've seen questions like this pop up from time to time and for whatever reason, the materials are not available in my region (texas) or I can't find something similar to achieve the outcome. The best i've been able to come up with is plaster of paris, which gives a great look if you are trying to do natural rocks or something along those lines, but it's extremely brittle and winds up chipping over time. I've also seen resin sprays but it seems to be something that you have to have major equipment for, or find a place that does it as a service. I've been thinking of using that gutter sealer that puts down kind of a thin layer of rubber (after adding plaster of paris) to prevent the chipping over time. I'm really just wanting something light, durable, and relatively inexpensive (around the $20.00 range) if such a thing exists.

Any tips?

Maybe testors dullcote? Or I know woodland scenics makes a terrain sealer

What materials?

also foam as it expanded or extruded pu?

You can honestly get away a few coatings of PVA glue watered down to make a fairly strong surface.

i also hear some people do it with liquid nails for a more rubbery surface to protect against wayward dice and bumps.

though i dont know if you can thin that,.

Spray varnish with melt foam.

Plaster bandage?

Like they used to use on broken arms and legs (well, they did here, anyway. Now they tend to use other ways to immobilise a limb).

Wet it, apply it, let it dry. Apply latex-based paint over it. It's tough but flexible and offers a fair amount of protection, but the plaster WILL still chip if you treat it roughly. Then apply further detailing. And varnish

I had to repair one of my club's hills (it was an enormous 30"x16" hill) that had seen better days. The underside was all torn and chipped, the surface likewise. It was a plain old shaped white expanded foam hill.

Plaster bandage strengthened the surface and the cut sides, whilst gluing it to some mdf protected the base. Then I used bog (Car body filler, known to some as "bondo") to fill the gaps before repainting the entire thing. That was 10 years ago and it's still going strong.

This stuff

https://hotwirefoamfactory.com/025_All_Purp_FoamCoat.html

Papier mache works quite well too. Think back to childhood, using paper/tissues/toilet paper soaked in a thinned down PVA mix, slop it on the foam and when it dries it'll be nice and rigid.

Common house plaster you buy from a hardware store for walls and whatnot also works.


Automatically Appended Next Post:

 John Prins wrote:
This stuff

https://hotwirefoamfactory.com/025_All_Purp_FoamCoat.html

What is that stuff?

+1 on the foam coat. That stuff is amazing and relatively cheap. After you coat the foam with it, you can spray your scenery which really speeds things up. Makes your pieces super durable too. Highly recommended.

AllSeeingSkink wrote:

 John Prins wrote:
This stuff

https://hotwirefoamfactory.com/025_All_Purp_FoamCoat.html

What is that stuff?

Foam Coat! You mix it with water and it's sort of like a drywall compound, only more manageable and made for, as it says, coating foam.

 John Prins wrote:

AllSeeingSkink wrote:

 John Prins wrote:
This stuff

https://hotwirefoamfactory.com/025_All_Purp_FoamCoat.html

What is that stuff?

Foam Coat! You mix it with water and it's sort of like a drywall compound, only more manageable and made for, as it says, coating foam.

Yeah, so is it hard like a plaster or more rubbery like urethane or somewhere in between like epoxy?

I've been looking for something cheap to coat foam for some lightweight car ramps and I'm wondering if that would work, be too brittle and just crush under the weight of a car or too soft and not distribute weight enough causing the foam itself to crush, lol.

EDIT: Looks like FoamCoat is a polyurethane, also looks like it's not terribly cheap in Australia.

I use. Durhams Water putty. It's very cheap and mixes as thick or thin as you want and drys rock hard.

AllSeeingSkink wrote:

EDIT: Looks like FoamCoat is a polyurethane, also looks like it's not terribly cheap in Australia.

Is anything? No, Foam Coat is not structural.

I Just use a base coat of interior Flat or eggshell house paint
usally in a base colour I want and can be gotten in a one pint sampler jar at most hardware stores for under 5 dollars..it goes a looong way
Can be thinned a bot with water and has just enough give to not chip under normal use ..

For doing it on the cheap, or if you have lots of area to cover, I'd say any combination of layers of PVA glue or latex house paint tinted to a useful color at the paint store. Cut your foam with enough detail that you can lay the paint or tinted glue on thick without obscuring it. The glue can be thinned with water and also tinted with acrylic paint or pigment to serve as a base for further inking or drybrushing. I can't say how many layers is enough to be able to spray paint over it... maybe do a couple of test pieces, but I'd say 2 might do it and 3 very likely will.

The purpose-made products mentioned are likely superior, cost and availability being the limitations there. Good luck!

If you want a coat of something that will allow you to spray paint foam Plastidip is the go to product. The spray cans of it do not melt foam and it's cheap and easy to get. (Ace, Home Depot, Lowes all carry it)

If you want durability go with a coat of modpodge before you paint, it'll work wonders.

If you want something you can throw around a room and it will still hold together get Bondo All Purpose Putty. That stuff hardens to rock like strength and can take a very serious beating. It's also fairly cheap and easily available (again Lowes, Home Depot, etc.)

 John Prins wrote:

AllSeeingSkink wrote:

EDIT: Looks like FoamCoat is a polyurethane, also looks like it's not terribly cheap in Australia.

Is anything?

Some things more than others. When I looked it up it was 6x the price it was in the US which made it more expensive than going to an industrial supplier I know on this forum we are typically discussing GW products being rather overpriced, but when something comes out at 6x the price, at that point it's usually not worth buying compared to local options.

Since my last post I did find an online art store that apparently sells it for only 1.3x the US price which is much more reasonable (at least I think they sell it, they don't have any pictures or anything but the description in their catalogue seems the same).

No, Foam Coat is not structural.

So how not structural is "not structural"? Most coatings aren't structural in and of themselves, that's why I asked....

"...is it hard like a plaster or more rubbery like urethane or somewhere in between like epoxy?"

One amazing thing about polystyrene foam is that in itself it is not structural but if you apply certain coatings (that also in and of itself is not structural) that is capable of distributing load all of a sudden you get something that IS structural and capable of supporting the weight of a car quite easily.

Sorry if I sounded like I was being a naysayer, I was simply trying to figure out if FoamCoat could perform that task, and whether it can or not is dependent on whether it's stiff and brittle like plaster or rubbery.

PVA glue works well, throw some sand on top of it for texture. It's a lot less expensive than all the fancy crap, and far more readily available.