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Hard Coat For Styrofoam Model

10/16/2017 1:46 PM

I have a styrofoam model that I want to preserve....the styrofoam is easily dented or damaged with foreign contact, but it's something that is to be actively used as a form, so I need a coating that will produce a hard impervious shell, and not react with the styrofoam....I'm thinking about 2mm thick shell....any suggestions?

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#1

Re: Hard Coat For Styrofoam Model

10/16/2017 2:00 PM

Two part, clear epoxy! No solvent thinners and formulated to brush on.

I did a huge ice chest for a deep sea fisherman using two part epoxy and glass over two inches of Styrofoam slabs and he loved it, used it for years. I used a commercial product called Fuzor 305 that was out of date from my lab at the time. It has a blue tint, but any two part, 100% solids epoxy/polyamide will be your safest. most durable choice.

Just brush a coat on (after testing on a scrap piece) , let it cure then coat again. if needed.

MIL-24441 Type III, Epoxy Polyamide - Protective & Marine

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#12
In reply to #1

Re: Hard Coat For Styrofoam Model

10/17/2017 12:56 PM

Good choice, Lyn. I did the same for my commercial fish boxes. Not sure if the model is a uniform one (square etc,) or rounded etc.. With my boxes, I glued 1/8th Philippine mahogany doorskin over the panels. Very lightweight and hard, impact wise,. Then glassed over that, to prevent too much resin soaking in, thus giving a higher glass-to-resin strength ration. For his application this is probably way overkill..

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#2

Re: Hard Coat For Styrofoam Model

10/16/2017 2:12 PM

Water based Truck bed liner. Plastikote, and Duplicolor are just a couple that make it in water base. You can even get it in rattle cans.

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#3
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Re: Hard Coat For Styrofoam Model

10/16/2017 2:28 PM

Interesting! Can you use that to make a hard, one-time mold?

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#5
In reply to #3

Re: Hard Coat For Styrofoam Model

10/16/2017 4:12 PM

Why not? You spray or brush it on your styrofoam (thick), let it cure, drill a hole in the bottom and pour a solvent in it. I have used the water based truck bed liner at work, once cured, it is has extremely good chemical resistance, including solvents (MEK, acetone). Styrofoam disappears very quickly in said solvents, leaving you a hollow, plastic mold.

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#10
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Re: Hard Coat For Styrofoam Model

10/17/2017 4:07 AM

For what material? If you are casing metal, no need to take the foam out.

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#4

Re: Hard Coat For Styrofoam Model

10/16/2017 3:31 PM

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#6

Re: Hard Coat For Styrofoam Model

10/16/2017 4:21 PM

I wonder, styrofoam dissolves in toluene but epoxy has a good resistance to toluene. So could a "lost wax" like epoxy/fiber glass mold be made with styrofoam being melted by toluene?

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#7
In reply to #6

Re: Hard Coat For Styrofoam Model

10/16/2017 4:41 PM

#5

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#8
In reply to #6

Re: Hard Coat For Styrofoam Model

10/16/2017 4:49 PM

Yes, Styrofoam disappears in Toluene also.......

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#11
In reply to #6

Re: Hard Coat For Styrofoam Model

10/17/2017 11:18 AM

The big issue would be whether you could get your wax out of the mold. The Styrofoam surface finish is a bit rough, so ejecting a wax pattern would be a challenge.

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#9

Re: Hard Coat For Styrofoam Model

10/16/2017 6:50 PM

Paint with household latex paint to protect it from the next coat of epoxy resin and fiberglass cloth.

Sand and Bondo as needed.

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#13
In reply to #9

Re: Hard Coat For Styrofoam Model

10/17/2017 1:01 PM

Have done that also , with the first styrofoam that came out in the 50's, using fiberglass over.

Another way we have made molds is to apply a mould release over the piece, then use Plaster of Paris with a fine mesh matrix. Let it cure, easy to cut in half, or what ever, and you have a female mold to do what ever you wish to. Maybe make another male mold..

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#14

Re: Hard Coat For Styrofoam Model

10/21/2017 11:23 PM

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