cracking paint

[bobcat68]

What i have is two stage paint ppg. The problem is i keep getting a hair line crack in the seam sealer a the rear deck filler panel. This is the second time it has happened,i would like there not to be a third. This is the only place it happens? The car is still in the shop it was painted about a year ago, just know getting time to work on it again not sure when it started to crack again. I sanded out the crack it's not in the sealer just the paint not the hole length of the seam and it's not lifting? Any thoughts?

[astroracer]

You used a seam sealer to fill the bodylines at the tulip panel to fender interface? Just confirming what I think you are talking about. A pic would be better. If you did use seam sealer that's the reason the paint is cracking. You should use a good filler or leave it bare. The seam sealer is flexing with temperature changes. The paint doesn't flex as much, which is causing delamination and cracking. Clean it out and re-finish with body filler.
Mark

[bobcat68]

Mark,
Its the deck filler between the back window and the deck lid.Also its a 68 f-body I should of mentioned that in the first post. Some people weld these seams solid to get a solid look but they where seam sealed at the factory.
Robert

[dhutton]

What kind of seam sealer did you use? I would recommend a good quality two part sealer from 3M. They have a self leveling sealer that remains flexible among others.

[bobcat68]

Medallion urethane, it stays flexible It was recomended thru a couple resto shops

[HotRod47]

That was your problem, it stays flexible and the paint doesn't. Like was posted above, a better solution would have been 3M Heavy Bodied Seam Sealer. I don't remember the part number off the top of my head. It is a two part, where as yours is a one part and remains flexible. If you don't clean that out you will have to fix that crack 100 times, it will never stop doing it.

[smhigh]

https://www.pro-touring.com/showthread.php?50028-Body-seams-below-rear-window

[bobcat68]

Thanks for the help