"Coatings for Blue Foam?" Topic

So, as a follow-on to my earlier, polyethylene foam question, if I use Blue Foam (extruded polystyrene foam – comes in blue, or pink, depending upon the manufacturer), what type of coating(s) can I use to protect the outer surface of it, besides just white glue, and/or latex paint?

I'm interested in creating a robust, hard shell, that won't crack, or flake off, and that is pretty lightweight.

Ideally, some sort of material, like a putty, or epoxy that can be poured over, or painted on to complex, curved shapes would be ideal, in many situations.

For some other, simpler applications, I'm thinking just plain old, thin, styrene plastic sheeting.

Presumably, since this stuff is made of extruded polystyrene, it might just be compatible with styrene plastic glues (and/or other plastic glues), so I can secure it, and the styrene sheeting together, at the same time.

Anyone know if that is true, and/or have any experience with that, and/or other robust coatings?

Make sure you remove any plastic covering, then coat it in a 50/50 mix of water and PVA. Paint with a water base paint.

They make some industrial products designed to specifically do that. Wish I knew more…

Low Temperature Hot Glue works very well for gluing it; High Temperature Hot Glue will melt the foam…

Whatever coating you apply, DO NOT HEAT TO SPEED THE DRYING PROCESS… I am working on a terrain project, applying Minwax Polyshades urethane-stain over the top, and I baked them at 170 F, to speed the drying process… The foam insulation melted from the heat! To clarify, I had previously baked several pieces of foam insulation at 170 F, for 30 minutes, but the melting occurred after 60 minutes.

Inexpensive PVA/White Glue is likely your best option. Latex paint will also seal it, if 100% coverage is achieved; any opening for solvents to reach the foam will result in problems. Cheers!

I really like: link

But any of their products will work. Products designed to work with foam. Not cheap, but the elasta-shield will provide a good barrier with two coats applied. I have produced coatings that have allowed me to spray paint large terrain boards and then easily glue/flock them. Tremendous products for these types of applications!

Latex paint works too

If you don't mind tossing the brush used for it in the end, one thing that I've used for larger projects and I picked up from the local store is a mix of plaster and wood glue.

One standard bottle of wood glue and a plaster mix that is about a gallon diluted even more after the glue is added to bring it up to one and a half gallons, mix it up and paint it on in thin layers.

Be careful most styrene glue will melt it….I use superglue

For a hard surface use a thin coat of Bondo or Durham's Water Putty (both have the advantage of being cold-setting and sandable)

I normally use wood glue or house paint see some of my stuff here link they have held up very well so far

I put sand onto the wet latex paint and oversprayed with dilute white glue.

For gluing pieces together I use either a rubber cement like Evo-stik or something like No More Nails.

How about plain old Spackle? The stuff used for hiding nail holes in walls before they're painted. Its also called Filler. If bonding is a concern, just poke several holes in the foam with a toothpick so the Spackle has a place to get into. It dries hard and is very cheap.

I usually paint on a coat or two of acrylic paste, then paint with artist's acrylics. I have also coated the foam with artist's acrylic matte medium. The acrylic materials work similar to how the product recommended by BTC Terrain above works, sealing the foam, and providing a protective, elastic outer coating. If you want a thicker skin, simply add more coats.

In my experience, rigid coatings on foam tend to get damaged more readily in handling, than more elastic or flexible coatings.

With modular terrain pieces, if the outer-most coating is acrylic paint, I spray on a light coat of Dullcoat, or similar flat finish. This will keep the edges of the pieces from sticking together and tearing away from the foam.

In the following link, link
a third of the way down the page are two photos of a large terrain piece made using the materials mentioned above, Additionally, all of the terrain, including the entire fortress on the rise overlooking the port is also made of blue foam finished with the above products.

Some description of their use is offered in the following links:

link

link

link

Hope this might be of some help.

Thank you for all the recommendations, info, and links.

Sounds like I have more options than originally thought.

Having a decent shell coating that can flex a bit does sound like a good idea, so I guess I'll just need to create a model or two, and do a little experimenting.

Finally something that I know well. I have the ultimate answer for you. Fasco makes a two-part Vaseline epoxy which will not melt styrofoam. It's an overnight dry product, and can be tinted with coloured powders, and messy as all get out, to use.

But it will harden, over the foam, and you can hurt someone by hitting them with the cured product. It can be applied in a cake-frosting manner, but it's better just to use disposable gloves, and massage-in the product, over two or three days.

Available at Glue Products, 561 833 1863, and I don't work there, but buy most of my furniture finishing product from them.

I am planning some 1/285th geomorphic terrain boards out of foam, and I will be using plaster cloth and sculptamold to fill-in and smooth out the transitions between elevations. Both dry to a hard surface that will resist dings and dents. They hold paint well, and are easy to flock.

Don