# painting styrofoam



## lewi55555 (Feb 22, 2012)

hi everyone u.k newbie here :wave:

i am constructing a series of model buildings out of styrofoam and i wanted to know how to prime, spray paint and lacquer it as regular primer dissolve.
maybe water based but which one?

thanks!


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## kit-junkie (Apr 8, 2005)

lewi55555 said:


> hi everyone u.k newbie here :wave:
> 
> i am constructing a series of model buildings out of styrofoam and i wanted to know how to prime, spray paint and lacquer it as regular primer dissolve.
> maybe water based but which one?
> ...


I'm not sure if this will kill your detail, but I would try something similar to a product we have here in "The States" called Kilz. It is a water based primer, so it shouldn't attack the styrofoam. As always, you should test it on a piece of scrap first.


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## rkoenn (Dec 18, 2007)

You are going to have to coat the Styrofoam with some type of thick sealer that forms a hard surface after it dries. Here is a link to one way to do it:

http://www.props.eric-hart.com/how-to/coating-foam/

It isn't that difficult, more like a bit time consuming and tedious.


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## Mark McGovern (Apr 25, 1999)

lewi',

First, welcome to the boards! I hope you get the answers to all your questions here. Before long you'll be answering other people's questions!

As you know, Styrofoam is easily melted by organic (oil-based, for those who haven't finished high school chemistry yet) solvents. What you need is an inorganic barrier that will adhere to the Styrofoam whilst preventing any reaction to the solvents in your paint. Kit-junkie and rkoenn are on the right track, a water-based primer is the answer. But it doesn't have to be Kilz, gesso, or joint compound; any water-based primer will do. 

Primers are formulated to provide better adhesion to a substrate. So, as the primer protects the Styrofoam from my paints they'll also help whatever I may be using to texture my constructions stick. I keep a can of cheap, dollar store household acrylic latex primer on hand just for priming Styrofoam.

While we're on the subject, here's a tip: since organic solvents can eat Styrofoam, you can use them to etch patterns in the foam. Let's say you're doing a large-scale brick wall and you want to add a few incised mortar joints to it. You could mask the wall so only the joints were exposed, then spray with an oil-base paint. The paint will etch the mortar joints cleanly if you don't use too much.

Best of luck with your projects, and please post some photos for us when you get them done.


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## lewi55555 (Feb 22, 2012)

wow, thanks for the quick and helpful advice 

ive sourced this in the uk 
http://www.paint-direct.co.uk/en-GB/product/548/979-0-0-0-0.aspx

so after this i can use regular spray paint? i will upload pics once its done.


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## djnick66 (May 2, 2008)

Testors spray paints say they work on styrofoam (and they do) but it never hurts to test it.


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## Bobj812 (Jun 15, 2009)

It was the year "Star Wars" came out, and my cousin and I decided we were going make our own SF super-8 movie. We made a group of buildings out of boxes and Styrofoam. I remember well spraying the gray and white paint on the pyramids and spheres and being proud that it looked a lot like concrete when done. And then being utterly astonished when I came back later to see the Styrofoam eaten away and eroded to globs of goo...


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## Mark McGovern (Apr 25, 1999)

djnick66 said:


> ...it never hurts to test it.


Agreed. Plus, it will help if you spray many light coats and let each dry before applying the next ones. That way you can build up the coverage you need without having to worry about the solvent bleeding through a missed spot in the primer and pitting your walls.


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## Mark McGovern (Apr 25, 1999)

Bobj812 said:


> ...astonished when I came back later to see the Styrofoam eaten away and eroded to globs of goo...


So THAT'S where they got the idea for _The Devil's Rain_...:dude:


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## rkoenn (Dec 18, 2007)

Mark, I believe you should be very careful about how you "etch" Styrofoam. What I mean is you need to be sure your etching medium will completely cure/dry/whatever. I remember as kids taking gasoline and putting a little on Styrofoam and what you ended up with was a gelatinous glob a bit like silly putty. It was probably toxic to handle too considering it had a fair amount of gasoline in it. We only did that a couple of times after discovering that it happened by accident. But you don't want to end up with strips of goo in your foam wall that never harden again.


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## kit-junkie (Apr 8, 2005)

rkoenn said:


> I remember as kids taking gasoline and putting a little on Styrofoam and what you ended up with was a gelatinous glob a bit like silly putty.


Homemade napalm! :thumbsup:


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## roadskare63 (Apr 14, 2010)

http://www.michaels.com/Top-Ten-Tips-for-Crafting-with-Styrofoam™-Brand-Foam/ae0088,default,pg.html

may help as well...

if you use foam core...you can get it at @ 1/4 inch thick...it is foam with a paper coating over the flat surface...this may provide additional protection, but the exposed areas where you cut will have to be sealed with water based sealer.

here is a 1:64 scale gas station i am constructing from foam core...i used pre textured plastic sheet facades i got from the hobby shoppe...but will be painting details with water based acrylic craft paints.





































good luck have fun....and welcome to the madness :thumbsup:


hey another thought...if you go to the model train or diecast customs and diorama forums, there are many more folks that may be able to shed more light for you!


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## Mark McGovern (Apr 25, 1999)

rkoenn said:


> ...What I mean is you need to be sure your etching medium will completely cure/dry/whatever...you don't want to end up with strips of goo in your foam wall that never harden again.


Point taken, Bob. I've used hardware store brand paint. Applied a little wetter than you'd do with mist coats, it lightly etched the foam, with nice, hard edges. The etching was pretty shallow - spray too much paint and it just eats the foam so you lose your pattern. For really deep shapes, you need to dig into the foam with a sharp knife to outline the shape, then dig the foam out.


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