I noticed the other night when I was working on the rudder spar that the primer was getting really scuffed up. So, out of curiosity, I ran my fingernail over a spot, and the primer scratched right off !!! I tested this in a few more spots, and everywhere I scratched, the primer easily came off. I have some other tail parts that were primed several years ago (I bought the tail kit "gently used" from an ex-builder), and their primer application seems to be holding up. All parts (old and new) were primed several weeks ago using rattle can SEM self-etching primer, and the primer I'm using now is the stuff that was given to me by the previous builder (and is thus several years old). It sprays on fine, and looks nice, but I thought it was supposed to be a little harder to scratch off...
Anyway, I'm just trying to figure out what's going on here. Should I toss this stuff and get something else? Anybody had this happen while using SEM's products? Could this be temperature related (even though it's not that cold here in TX)?
(And BTW, I'm not trying to start any rattle can vs. etch/alodine/prime debates here. I'm going rattle-can all the way - well-except maybe in the wings around the fuel tanks - jury's still out on that one...)
Anyway, I'm just trying to figure out what's going on here. Should I toss this stuff and get something else? Anybody had this happen while using SEM's products? Could this be temperature related (even though it's not that cold here in TX)?
(And BTW, I'm not trying to start any rattle can vs. etch/alodine/prime debates here. I'm going rattle-can all the way - well-except maybe in the wings around the fuel tanks - jury's still out on that one...)