Clear Coat-repair problem

I decided to repair the hanger rash on my Geo Juno. I painted it with Dupont Chroma Clear top coat about 7 years ago. Came out fine, so I wasn't worried about the refinsh of a couple areas.
Well I had done this 2 years ago when the plane rack detaqched from the wall and the planes fell leaving some patching to do on the underside of the wing. No problem then, either.
This time I struck out. When I taped off the areas for the second trim colors, the tape lifted the clear coat in several places upon removal. It just came off like little pieces of saran wrap. Along with the base colors over it, etc.. So, for now, the repairs look pretty cruddy, and I'm out of time to do more for this season since it starts for us this weekend! Wish I knew why this happened.
Bill <><

What's underneath it, Bill? It is obviouisly an adhesion problem.

I bought a Mong Sport Bi-plane a number of years ago that had been enameled over dope. It looked nice and shiny, except, on closer examination, the enamel hadn't stuck down. I ended up peeling it all off, in sheets, sort of like you describe. The dope underneath was just fine. I went back and refinished it in just plain dope.

If you put a clear top coat over a dope base, that dope base can gas off over time and the top coat won't let it escape. That is one source of problem. However, some of these automotive finishes have to be recoated either within a short period of time, or they need to be left to cure for a considerable amount of time before another coat goes on top. A third possibility, I suppose, would be incompatibility between your base coat and top coat.

So, basically, what did you use underneath the top coat, and how long of a time was spent before the top coat was applied?

may be you got some of the stuff they used on late 80's to early 90's crysler products.

>may be you got some of the stuff they used on late 80's to
>early 90's crysler products.
>
>Tom

1988 Dodge black with clearcoat. Just after the warrenty period for the paint it started getting the worst case of Leprosy that you've ever seen. $1,000.00 for a repaint, definitly not done by chrysler or their products.
Dennis

LAST EDITED ON May-12-04 AT 05:47 AM (CDT)
 
Hi Bill,
Did you use the low-tack automotive masking tape (blue or green) or did you just use regular masking tape? Just curious. I had a similar experience last year using the regular stuff. I switched to the low tack tape and have had no problems since.
Leonard is also right about the automotive finishes. I occasionally use the Napa brand CrossFIre urethanes and they recommend shooting the clearcoat within 24 hours of the last base coat. Otherwise the wait is 2 to 3 weeks.

Hi Guys,
Thanks for all the replies.
After consideration of the problem, it appears that the Dupont Chroma Clear had an adhesion *life* on this plane. It wasn't apparent until I had to *mess* with it the second time.
Like I said, the original paint job is approaching 7 years old. The repairs needed were all in the nose of the airplane where the most abuse occurs. The clear coat is somewhat brittle, and the adhesion of the original clear paint, while not appearing to be *bad* originally, has seemed to weaken over the years.
In Jan. of 2003 I did some minor repairs in the same areas to get ready for KOI that year. I did not have these problems then.
This time I had to take it down to bare wood in an area (blind nut in engine crutch let go) and I refinished about 6 inches of the fuselage nose, and the nose fo the cowl (redid the whole cowl, with a couple areas of bare wood).
The 1/8th" blue 3M tape is what pulled up the clear, basically in a 1/8th" *line*.
The ship got a third in Concourses at Flushing when it was brand new, and now the nose looks worse than something I waould have done when I was 13 years old. Just very disappointed in how this *repair* came out.
Also, it might serve as a warning to anyone else in this same situation. Having done a bunch of repairs/blending with models, and real cars, using the same basic materials a bunch of times, I have not had this situation occur before.
Guess it's really time now to build a new PAMPA plane!
Thanks guys!
Bill <><

Bill,

I'm getting ready to rebuild last year's plane that exploded in the air (that was fun). It has an auto finish on it, but I intend to strip it all down to the covering or possibly bare wood, so I shouldn't have a problem.

What strips off catalyzed poly-urethane? Lacquer thinner? Acetone? MEK? plutonium?

The plane will get a new fuse with recycled wing, stab and control surfaces.

>What strips off catalyzed poly-urethane? Lacquer thinner?
>Acetone? MEK? plutonium?

Airplane stipper. They sell it at auto paint stores. Strips anything.

Nasty stuff I bet.

Why not just leave the paint on the parts?