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Old Oct 01, 2010, 10:28 PM
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ny_hawk's Avatar
New Rochelle, NY
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The definitive paint for EPO foam

Okay well, I have looked and searched and have yet to find the final word on what the best paint is for EPO foam...

I am testing and have tested several kinds of paints and so far none adhere the way I want them to..

So out of all the brilliant minds and vast experience set here has anyone found a paint that will actually BOND to EPO foam. And by EPO foam I DO NOT mean some other kind of foam... The word foam is often tossed around these fora quite a bit and it's silly because different foams do not have the same properties at all..

So far I have tried:

"Epoxy" paint
Plastic paint
Enamel paint including Testors $500 per gallon paint.
Several Rustoleum primers and paints

Wondering about polyurethane based paints... So far doesn't seem like there are a lot of this type out there..

So has anyone found a paint that actually bonds to EPO foam? I refuse to believe that nothing will properly bond to this surprisingly nonreactive type of foam.

Jim
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Old Oct 02, 2010, 01:25 AM
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East Anglia, UK
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what is EPO foam. I know EPS and EPP but EPO?

Anyway, any foam needs a filler primer layer. Its normal to start with Spackle filler and one or more coats of clear water based acrylic varnish sanded down, or glass and epoxy.

Over thatt we normally spray Humbrol/Tamiya style oil based enamels.
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Old Oct 02, 2010, 01:34 AM
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Quote:
Originally Posted by vintage1 View Post
what is EPO foam. I know EPS and EPP but EPO?

Anyway, any foam needs a filler primer layer. Its normal to start with Spackle filler and one or more coats of clear water based acrylic varnish sanded down, or glass and epoxy.

Over thatt we normally spray Humbrol/Tamiya style oil based enamels.
EPO stands for Expanded PolyOlefin... It is a very durable foam with a nice natural finish, normally has large beads, is shiny in appearance and is very flexible, not brittle.. It is also very non-reactive.. It handles normal CA and I have not found any paint or solvent that eats it up, though something may..

Glassing is fine but there must be a best paint out there for EPO (the manufacturers often paint these models).. Polyurethane glue is used to bond it so perhaps a paint based on that or a primer.. Also wondering about polycarbonate paints..

Jim
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Old Oct 02, 2010, 02:45 AM
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Nothing sticks to olefins at all.

One of its main features.

Teflon apart, its the nearest to non stick there is..think polythene.

You might find a solvent that attacks it enough to get some form of key.

Try some on scrap and see.

If CA sticks it, which surprises me, why not paint Thin CA over the airframe?

Hmm. Dome olefins seem to take cellulose and alcohol based inks..

have you tried normal car solvent primer...it might works.

Once you have a primer down, all else becomes relatively trivial.y
Id try clear dope with cellulose thinners, ad cellulose car spray primers first.

Also some car fenders are made of olefin type plastic, and you may be able to get proprietary etch primers made for those that will attack it enough to get a key...
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Old Oct 03, 2010, 06:20 AM
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Quote:
Originally Posted by vintage1 View Post
You might find a solvent that attacks it enough to get some form of key.
If I can find some solvent that attacks it then how to use this as a key?

Quote:
Originally Posted by vintage1 View Post
If CA sticks it, which surprises me, why not paint Thin CA over the airframe?
I had thought of this but it seemed like cleaning the bathroom with a toothbrush... lol Also not sure how CA would sand... Spray on CA would be cool.. Never seen it though...

What kind of brush would work with CA?

Quote:
Originally Posted by vintage1 View Post
have you tried normal car solvent primer...it might work.
Hmm, no haven't.. Will look into it..

I'm trying a polyurethane base coat now.. So far no great results..

Thanks,

Jim
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Old Oct 03, 2010, 02:02 PM
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Riverhead NY USA
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Tom Hunt uses house paint from Home Depot mixed at the store to match his warbird color schemes.

http://www.rcgroups.com/forums/showt...t#post15880398

The secret to getting the paint to stick seems to be washing the plane (foam) down with alcohol before painting to remove the mold release agent. Tom's P-51 has been around for months now and shows no real wear on the paint.
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Old Oct 06, 2010, 09:50 AM
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Krylon fusion has seemed to work for me on EPO foam. Just tested it out, and it looks great. On EPS foam, it will eat it alive if applied heavily, and sometimes works in small amounts. On EPS, I'll use Krylon Short Cuts spray paint.

Clean the foam lightly with rubbing alcohol and let it dry, then spray the Krylon Fusion over it, and after it dries, use something like Minwax polycrylic clearcoat to seal the paint.
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Old Oct 10, 2010, 04:16 AM
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Okay well so far I have come up with a process that looks like it may give me the results I want..

What I was really going for that perhaps I did not make clear here is to put a real finish on the foam but without glassing it... I wanted a finish that would not look like foam and that would be ding resistant...(the constant new dings make me nuts)

So far what I did was this..

1. Clean surface with alcohol..
2. Apply a light coat of CA over the area..
3. Sand above lightly 220 grit..
4. Apply a coat of primer..
5. Sand above 120 grit..
6. Apply a coat of finishing epoxy..
7. Sand above.. 120 grit
8. Apply a coat of primer..
7. Sand above.. down to 400 grit
9. Paint as desired..
10. Apply a clear coat..

I am up to 8 now..weight gain seems minimal..

The wing looked amazing after the epoxy was applied and appears to be much more ding resistant.. I had tried epoxy before but it didn't cover correctly, with the CA and primer this seems to help it cover evenly and it also seems to self level to a large degree..

In the end the finish should look like glass without the glass and be much more ding resistant.

I may try using different combinations of the above.. Such as CA with no epoxy as a base, or two coats of epoxy... In the future my technique for applying the CA will improve and the process will keep evolving..

Jim
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Old Oct 10, 2010, 11:58 AM
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How do you spray CA?

A thought just crossed my mind. I used to work with leather a lot and used dye to color it. I have never tried dye on foam but wonder how it might work. Anyone ever tried it.
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Old Oct 10, 2010, 02:50 PM
Since 1952
Canada, AB, Edmonton
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Jim, I came across this while looking around the Klass Kote site recently:

http://www.wowplanes.com/product_inf...roducts_id=130

Liquid Sheeting, it's called. I had never heard of it before, have not used it, and have no idea if it's any good.

FWIW.
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Old Oct 11, 2010, 11:21 PM
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Quote:
Originally Posted by WillyAA View Post
How do you spray CA?
I haven't got that down yet.. This first time out I simply wiped it on with a cloth, well several cloths..

Aside from spraying it on, the cloth kept binding with it but I realized that I could use a foam brush with foam safe CA to get better coverage..
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Old Oct 11, 2010, 11:27 PM
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Quote:
Originally Posted by Harry D View Post
Jim, I came across this while looking around the Klass Kote site recently:

http://www.wowplanes.com/product_inf...roducts_id=130

Liquid Sheeting, it's called. I had never heard of it before, have not used it, and have no idea if it's any good.

FWIW.
Hey that's interesting.. Similar idea to what I am doing.. Wonder if it definitely works with EPO and how strong of a 'shell' it has...

Jim
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Old Oct 13, 2010, 02:37 PM
Will fly for food
Maryland
Joined Sep 2004
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Why would you layer epoxy and primer?

The primer doesn't bond that well to epoxy and the layers can peel off.

Epoxy with lightweight cloth for strength. Surfacing primer to fill the grain. Paint.
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Old Oct 14, 2010, 04:06 AM
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Originally Posted by Pinecone View Post
Why would you layer epoxy and primer?

The primer doesn't bond that well to epoxy and the layers can peel off.

Epoxy with lightweight cloth for strength. Surfacing primer to fill the grain. Paint.
Not clear really.. You seem to suggest using primer over the epoxy? I used primer over the epoxy for the same reasons, always have.

I haven't had a problem with primer sticking to the epoxy at all.
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Old Oct 14, 2010, 02:05 PM
Will fly for food
Maryland
Joined Sep 2004
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I am talking about doing the epoxy - primer - epoxy - primer - epoxy layering that was mentioned.

A good way to develop delaminations.

Epoxy then primer then paint, tried and true and well proven to work
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