Hi everybody
does exist a spray to use on foam in order to make it harder.
I saw some foam planes whose wings are covered by a thin layer like a plastic layer.
I know that we can cover foam with fiberglass coat , but I am asking if there is a spray that can make the job
thx a lot

yes have a look here http://www.demandproducts.com/liquidrock.html

Thx erase for your fast response
I am trying now "outdoor satin sealer" , I don't know if it will work
then , if it is still flexible , I will try to spray varnish on it , I hope it will form an isolant in order the varnish doesn't etch the foam
results to be sent later :)

something in my head is saying that shellac is a good way to seal foam against stronger coatings. shellac is alcohol based and shouldnt damage the foam. you then maybe able to coat it with regular fiberglass resin perhaps mixed with a very fine filler such as wood flour or cabasil.