Painting Foamies.

As some of you know I pranged my Sky Trainer ( again). It is now under repair but I'm at a loss as to what paint to use on the repairs.
There are a multitude of videos on YouTube advocating everything under the sun, & quite frankly I'm getting one of my dizzy spells!
Any ideas?

I paint my Depron (not exactly the same as EPP) with artist's acrylic paint. Comes matt, semi & full gloss.
Cheapest by volume are the big 500 ml bottles but you can multi colour packs of small bottles or tubes.

I am not sure if it''s made from EPP ( Expanded polypropylene) or EPO ( Expanded polyolefin) or if it makes a difference ! You don't use any form of primer then?

No primer but two coats (brushed) may be required depending on how 'thick' you want the colour to be.
Water based, but 'shower' proof when dry, they are pretty thick.
Two coats, with a light sand in between, on the long Q400 fuselage gave a reasonable colour and finish.

Taken with a flash its actually more purple!
Including a light white coat on the white Depron wings and tail the paint added just under 1 oz to the all up.

Acrylics are the way to go, in my experience there totally waterproof ( I use them on fishing floats as well as for my art).

I agree with acrylic, household emulsion and water based gloss are also a type of acrylic paint, the key point is that they are water based and not solvent based. I broke the fuselage of my Bix 3 completely in half and repaired it with a carbon fibre tube and epoxy. I then used white emulsion to paint over the join, sanding between coats. ..... It was very rough brush job and I'm sure I could have got a much better result with a roller or spray, but I just wanted to get the thing flying again quickly.
The break is just under the motor where the Fuz goes narrow. As you can see, with a bit more sanding it could have been a nice smooth finish. A coat of clear lacquer might have helped as well. ..... You have a great range of cheap colours by buying the little emulsion tester pots as well.

Thanks chaps. I found a local hard-wear store that sells a good selection of acrylic hobby paints.
Also a limited range in spray cans, including clear for a nice shiny finish, I do like shiny !

I am a bit peaved with the suppliers I got the spare wings from though. Unpacked them to find they hadn't supplied a new carbon fiber tube to join the wings!

crash happy
Do be careful with spray lacquer even if they are 'acrylic'. With spray its not the 'paint' that is the problem but the propellant. Most will attack the foam until it dries off completely.
I have sprayed acrylic painted Depron with car clear lacquer to get a glossy(ish) finish but only by using very light coats and being super careful to avoid creating local 'wet' patches as these soften any previous lacquer coats, then the acrylic paint, allowing a chemical attack on the foam. Whilst not usually structurally serious its does rather ruin the gloss effect you are trying to achieve!
The only recovery I have found is to leave it for several weeks to fully harden and then to 'start again' rubbing down with wet and dry.
My Fairey Delta had the benefit of this approach.
It went from this dead matt (actually emulsion) as built.

Sanded to this.

To this acrylic paint + lacquer

And it probably helped that the original paint had dried for 2 years before it was repained!

Well That turned out nice Quorneng! As I said I am not sure which foam it's made of. When I repaired it last I used a light coat of spray filler as a primer, then a coat of plasticized car paint. It didn't eat the foam but when it hit a well placed light tower paint came down like snow ! It was dead easy to get the paint of the salvageable bits though, just put gaffer tape on, pull, and the paint came off with it!
I am going to follow the general consensus of opinion and use acrylic. I'll experiment with the clear on a piece of old wing.
It's definitely going to have a lot less paint this time. Perhaps it might get off the ground without flaps!
Thanks for all the advice.

I took note of this Eric "Heat-shrink films won't stick either, but oddly - epoxy will! Self-adhesive tapes will stick"
I use gallons of epoxy for boat repairs so I tried some epoxy primer on a scrap bit of foam, works great.
One thin coat applied by brush is perfect. If you try & lay down several thick coats the foam goes soft, but after four days it had hardened again & it sticks like sh-t to a blanket. The primer can then be painted with polyurethane to give a gloss finish. Thanks for that little nugget.

Absolutely. One thin coat is definitely the best way to go.

Use an old credit card to squeegee epoxy on to the surface. It will only go in the grainy bits of the foam and go on thinner so not affecting the foam at all, but uses less expensive epoxy and makes for a better finish. This method also works well on wood, for you old fashioned chaps.
Wouldn't it be great to find a material that didn't need its surface filling?

Martin