scuffing is all that's required, and it needs to be done if the epoxy primer is over 72 hours old, not a big deal, need to break the surface 'gloss' to provide good adhesion for the next coat regardless what it is, other types of primer are not moisture proof
Eric - I've had chemically stripped metal phosphate treated, and in good storage the metal stayed 'virgin' looking for years, but I still epoxy prime everything now regardless if it'll have to be resanded - save some work/time now, wind up spending even more down the road totally stripping and redoing pieces, etching primer that's sat for months/years should be totally removed ... YMMV
Bill
