Paint adhesion to foam

[octagon]

Hey guys,
I am just finishing up a Windrider Hurricane. It of course comes unpainted, so I decided to use Tamiya acrylic and an airbrush to finish it as the plane Willie McKnight flew in the Battle of Britain.  I have good results from the colour point of view, but the paint does not adhere to the foam underneath very well. That is to say that even normal handling of the plane will result in paint scrapping off to reveal the foam underneath. It is to late to do much on this plane, but is there something I should have done to the foam before applying the paint? Some process to make the paint more adhesive to the foam ? Is there anything I can add over top that will help at this point?
Thanks in advance
Rob

[Michael]

I have painted regular foam with water-based acrylic paint, by hand-brush, with excellent results.


I have painted the new type of rubbery foam (EPO?), such as on the newer Parkzone and E-Flite models, first with a coat of grey primer (Tremclad, or similar, enamel based spray paint from Home Depot), and then the same brand in various colours for finishing. (Always test on a piece of scrap foam first.)


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Now that you already have an unstable finish of foam, you'll need to find a clear-coat that doesn't affect the foam or the paint.


Test, on a scrap piece of foam with the same paint you used, with a clear spray lacquer, matte, satin or glossy, whatever suits the model. If that ruins the paint finish or melts the foam, try to apply by hand-brush a water-based polyurethane on another piece of scrap. The last may actually be the best method.

[Papa]

One of the problems with foam is it is molded. Manufacturers use mold release to stop the foam from adhering to the mold. This also prevents paint from adhering. With the raw foam you should wash it thoroughly with soapy water to remove as much release as possible and then use Michael's method.
Use of an intermediary like primer is good as it links the two surfaces and creates a minute 'tooth' for the paint to adhere to. Clear coating will protect the paint job.


Jack.

[octagon]

Thanks guys. I did have some matt clearcoat that I was going to apply to dull the finish and the decals down. Dave at Pinnacle suggested it. Appreciate the help.
Rob