"Richard Riley" wrote

My Long
EZ had acrylic enamel over an unknown dark grey primer (circa 1989, it
wasn't lacquer based but I'm not sure what it was) - when I went to
strip the paint the topcoat peeled off in large sheets, it hadn't
bonded to the primer at all. I don't know what the failure was, it
might have been either the primer or the topcoat. So I'm strictly a
Linear Polyurethane guy now, from primer through clearcoat.

I suspect the problem was that of the primer, not of the topcoats.

Ever notice(d) what the 1987 and 88 (and perhaps 89) automobiles with light blue
and gray paint did? Most, if not all had the paint peeling off in sheets or
fading all of the way off, without starting to strip them. You may have not
noticed that, but I did. I had one of the automobiles that had said light blue
paint. I would stand there (usually at the gas pump while I was doing nothing
else) and peel off silver dollar sized sheets of topcoat with my fingernail.
There was a recall that I did not take advantage of, (because I was a
contractor, with 7 people depending on my van being there with the tools
everyday) until it was too late, and had expired. Expired? Ridiculous. That
sort of thing should never expire. I still have not forgiven GM for that one.

I was told that the problem started while the paint companies were trying to
meet new regulations for the amount of volatiles in the paint, and the new
formulas did not have adequate UV resistance, which would cause the bond between
topcoat and primer to break down. The light gray and blue topcoats were the
worst at letting UV through, I guess. I don't know for sure if that was the real
answer, but there was a real problem. Perhaps that was a common link with your
problem.
--
Jim in NC