# About sealing foam



## septimuspretori (Jan 26, 2011)

I have a question for those of you who use foam to make your own bases. What is the best way to seal the foam? 

Ben


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## Chinxy (May 23, 2003)

I've been using Mod Podge since back in the 90's! It seals great and it's clear. It dries very hard and you can paint over it very well. You can pick it up at Michael for about $5.


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## Mark McGovern (Apr 25, 1999)

Septi',

I like Zinsser Bullseye 1-2-3 Water Based Primer. It sticks to anything and seals the foam. Once dry you can paint over it with anything. It's more expensive than hobby products, but is useful for painting elsewhere around the house.


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## Night-Owl (Mar 17, 2000)

I've had the best luck with Mod Podge.


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## djnick66 (May 2, 2008)

I've sealed foam with Durham's Water Putty

http://www.waterputty.com/

Its easy to mix, has a nice color and texture, and is very hard and durable. You can also use it sort of like plaster to do some casting work. You can also carve and shape it once it is hardened. The stuff sets up quick, is cheap, and easy to use.


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## veedubb67 (Jul 11, 2003)

Have to agree - Durham's Water Putty.

The stuff dries rock hard and can be sanded.

Rob
Iwata Padawan


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## Spockr (Sep 14, 2009)

djnick66 said:


> I've sealed foam with Durham's Water Putty
> 
> http://www.waterputty.com/
> 
> Its easy to mix, has a nice color and texture, and is very hard and durable. You can also use it sort of like plaster to do some casting work. You can also carve and shape it once it is hardened. The stuff sets up quick, is cheap, and easy to use.


If you are talking about covering foam 'board' I'll 2nd DJnick's suggestion about Durham's. Its lightweight, strong and easy to work with. It's really inexpensive and can be found in many hardware stores. I used Durham's and foam board to extend the floor of my Nosferatu castle floor. I made a mixture that was a little thinner than peanut butter and spread it around with a spatula. I originally intended to carve the stones when it dried but found that it had great work-ability with dental picks while it was still damp. I extended the drying time by covering the un-carved sections with Saran wrap. Sealed it with primer and painted as usual.

Another product I also like for terrain on foam board is called Sculptamold. Its heavier that Durham's but it can be stacked high and bumpy. It's a "hobby" item but a big bag costs under $10.

Either product is great an both offer a variety of textures depending on how much water you add.


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## Mark McGovern (Apr 25, 1999)

The main reason I apply the Zinsser primer is, it makes the styrofoam surface more receptive to any other coating as well as protecting it from the solvents in oil-based paints. I've had some texturing materials flake off styrofoam; the primer helps prevent that from happening. So priming the styrofoam is always my first step, no matter what I intend to do to it later.


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## septimuspretori (Jan 26, 2011)

Thanks a million, guys...you've given me some options that are all relatively inexpensive, so I'm sure I'll eventually try them all...thanks again for the info!

Ben


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## spawndude (Nov 28, 2007)

What is the difference in Durhams water putty and plaster of PAris?


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## djnick66 (May 2, 2008)

spawndude said:


> What is the difference in Durhams water putty and plaster of PAris?


Aside from both coming in powdered form they are really totally different. Water Putty also is permenant. It won't get mushy or crumble like plaster, which for the most part is fairly soft. Comparing water putty to plater is like comparing epoxy to elmers glue.


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## Mark McGovern (Apr 25, 1999)

Plaster is also cheaper than Durham's. So if you're thinking of a large scale application - say, covering a big piece of foam for a diorama - the plaster would be more cost effective. You'd probably want to support the foam on a wood base so it couldn't flex and crack the plaster, Durham's, or whatever.

If strength is more important, Durham's is the better option. I've got a Polar Lights Mummy underway, and wanted to put a wall behind it. A thin coat of Durham's over the Zinsser primer was just the ticket to turn a chunk of Styrofoam into "stone".


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## djnick66 (May 2, 2008)

Unless you are doing a massive diorama thats like 4 x 3 feet, one can of Durham's would be more than enough to coat some styrofoam. Good quality hydrocal plaster too (not the cheap stuff) is rather pricey and often you need to buy very large bags of it (shop near me sells it in 25 l b bags).


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## apls (Dec 5, 2005)

David Fisher uses liquid resin, anyone ever try that?


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## Mark McGovern (Apr 25, 1999)

I tried to glue Styrofoam with a two-part epoxy cement and it attacked the foam; same with superglue. There are many resin products, so if Dave Fisher says he has one that works I'll take his word for it. But surely resin would simply create a smooth surface - good for a shiny floor, the inside of a UFO, or something similar. Either plaster or Durham's will impart a rough texture that can be modeled to represent stone walls, a natural landscape, etc. And I have to believe that they'd cost a lot less than any resin material.


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## apls (Dec 5, 2005)

On Monstermania dvd, David, after using a wadded up piece of foil,on balsa foam, used resin painted on with brush to seal the details that he cut into the foam.


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## otto (Jan 1, 1970)

For balsa foam, I like using a mix of 50% water and 50% Titebond wood glue. Paint the stuff on after the carvings finished, it soaks in a few milimeters and makes the surface rock hard when dry. By mixing with water, it goes on easy and doesnt obscure details. Then I paint and seal with clearcoat. Cheap, easy and effective. The Balsa foams pricey, but the glue and waters cheap!


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## Mark McGovern (Apr 25, 1999)

But Balsa Foam is not the same as Styrofoam. I'd be leery about using resin on Styrofoam without testing it first. And again, both plaster of Paris and Durham's Water Putty can be found much cheaper than resin products. Save your money for important stuff like aftermarket parts!


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## djnick66 (May 2, 2008)

resin will melt any kind of styrofoam I have ever seen. Plus its expensive.


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## septimuspretori (Jan 26, 2011)

Thanks again for all the help, everyone!

Ben


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