C2 Painting Question

[Philip Whitaker Member# 2024]

I'm ready to paint my 64 convertible and have noticed that the body seams (where the panels are joined by bonding strips) become noticeable to the touch (barely noticeable to the trained finger of the painter (myself) ) when the panels are subject to a hot soak in the sun. I've painted Corvettes before and not noticed this. What I'm feeling is a slight dip (a few mills deep) where the seam is, when the panel is warm. When the panel cools in the shade the dip goes away.

The car was stripped to bare glass with chemical stripper (in small sections) , properly washed down with water and MEK immediately following stripping, recoated with red oxide polyester primer, boarded out to a 280 grit finish, and then primed with Dupont Uro Prime and blocked with 600, in preparation for the top coats.

While the prep looks great, I'm still concerned about the phenomenon that is occurring at the body seams. While it doesn't seem noticeable to the eye, it is in fact occurring.

Has anyone else noticed this? Is this normal? I know that some one out there can answer these questions for me. I don't want to shoot the top coats until I've figured out if I should be concerned or not.

I know that the seams on original cars can be noticeable. My car had one enamel repaint on top of the original lacquer paint, and the seams for the most part were all noticeable. However, I was under the impression that it was due to the paint materials shrinking over the years and the cold flow of the polyester panels.

Any advise regarding this matter will be greatly appreciated.

Thanks, Phil

[Mike M.]

Re: C2 Painting Question

If you do not wish the joints at panel junctions to be noticably shrunk in the sun, then i would(and have) grind the joints then glass oven the seams with resin and cloth and begin the pre-paint prep all over again. if you don't mind some noticable seam whrinkage when in sum, then blow paint on it now. mike

[Chuck S.]

Re: C2 Painting Question

Mike, you said "resin and cloth", but did you really mean "resin and fiberglass mat"?

[Philip Whitaker Member# 2024]

Re: C2 Painting Question

Mike,

Thanks for your response. My concern isn't so much that the seam is appearing under the suns rays and then disappearing when the car cools, but more that is this normal. If you're telling me that this is common to all C2s that don't have the seams modified, then I won't worry about it any more and I'll proceed in shooting the top coats. I feared that this movement in the paint might cause it to crack.

Do you think that there would be anything to gain by repriming the seam and then dry sanding it in the sun to minimize the shrinkage seen in the sun? Or would this just cause me problems when the car body cools off.

Thanks, Phil

[Mike M.]

Re: C2 Painting Question

chuck; you're correct. i meant random fibered mat, not the patterned cloth. thanks for picking up my mistake. mike

[Mike M.]

Re: C2 Painting Question

appear and disappear might be normal on a 10 to 15 year old original corvette lacquer job but if you allow the coats of primer you've already applied to sit in the hot sun for many days( we typically let em outdoors in the summer sun for 3 months to allow evaporation to go to completion.) then i'd guess it'd be several to 10 years before shrinkage at the bonding joints would be evident to the naked eye. I have never seen cracks at the junction of panels on an original paint c-2, just shrinkage. i'm no professional painter but i think i'd let the body sit in sun for months (or in a super heated garage) then see if the shrinkage persists. good luck, mike

[Philip Whitaker Member# 2024]

Thanks Mike *NM*

[Dennis C.]

Re: C2 Painting Question

Philip - Usually on my first coat of polyester primer over bare glass, I only shoot the seams. This seems to do 2 things. Help with the fill from seam shrinkage and give those darn little pin holes a chance to rear their ugly head. I let this cure and then sand - and shoot the whole body. Cure, wet sand and shoot again. At that point I don't recall seeing any more problems. Dennis