are you taking it off a wing or fuse?the way i removed it from my wings on my older ucontrol planes was use 120 grit sandpaper and sand the ribs then it falls off between them,on a fuse or solid wood i also sanded but that was a bit more difficult.i sand as much as i can get off and smooth the wood with a finer grit paper.i havent used silkspan for many years now.