It rips off any epoxy that seeped through the peel ply – that is what it is there to do.  It peels off the excess, and it is finely porous to allow the excess to seep through so it can be removed. If there is amine blush it should be on the discard side, though this was not an issue with polyester and vinylester resins. The peel ply leaves an imprint of its contact surface on the remaining laminate. The peel ply I used many years ago left a finely textured surface. I don’t know if this is always the case though. Cheers, P