Sanding and finishing EPP Foam?
I am building a Cloud Clipper flying lawnmower from plans. The plans/instructions called for mostly foam for the build and did not specify which type. I went with 3" thick 1.3# EPP foam for the primary airfoil. I built my own hot wire cutter which worked pretty well. Now I am at a point to finish the airfoil, i.e. filling and sanding some of the bumps and pockets that are bound to come up. However, in sanding the EPP foam even an 80 grit sandpaper does not seem to do anything to the foam, the sanding bar seems to simply run over the foam with no change in the surface texture.....hmmmm. I tried looking on the internet with some explanation as to how to sand/finish epp and prepare for covering but am coming up empty.
Any help appreciated.
Also, based on the plans/instructions I am planning on covering the foam with Sig silkspan covering by adhering it with thinned alphetic resin and then painting with acrylic paint - this already seems like a big pain to me and I haven't even started! Any other covering recommendations?