RE: Can EPP foam be covered with heat-shrink covering?
Yes ! I have covered several epp foam wings with a low temp covering and a couple with Ultracote.
You need to have a good covering iron with good temperature control, I use a Black Baron that has a control with degrees marked.
First I use a spare block of styro foam to clean the surface of the wing of any loose strings.
Next I cover the wing with a coat of 3M 77 adhesive spray.
I cut out the approximate sizes of covering, I smooth out the covering over the surface and trim to fit with a 1/4" overlap.
Lastly I set my covering iron to 175 degrees and smooth out and seal the laps.
If the covering becomes discolored your iron is too hot. Try on a spare piece of foam.
After a while the covering may become loose, simply reseal with the iron.
Good Luck
Woodduck