Ok, I welded my emblem holes up on my quarters on both sides and spot puttied. When I sanded it down I went through the clear and base. I prime with 2k as soon as the primer hit the panel the paint cracked and spidered even were I didnt go through the clear. trunk and door didnt do this and paint and prepped the same time.

When the paint cracked it went through the clear and paint. Last night I sand the areas and used dupicolor rattle can primer on it to see if if would react again (I didnt want to mix and clean the gun it was late and the area was the size of a dollar bill). this morning I dry blocked that area and the rattle can primer is still there. Do I need to get rid of that primer and prime with the 2k for the paint to lay right? and what would make this happen? paint to wet?
http://i154.photobucket.com/albums/s254/chevelleman66/DSCF1752.jpg

http://i154.photobucket.com/albums/s254/chevelleman66/DSCF1747.jpg

Did you fill those holes with just filler? -if so they won't hold up.

The cracking you describe is actually lifting and you may need to seal the repair area to keep the solvents from attacking that old paint.

So can I spray 2k on it without thinning it out? or will I need to strip it down to bare metal? Also when I was wet sanding the fender I went through the base and clear down to the primer, should I spray light dry coats of primer on it.
I have never had to seal a car, I might add a little base color to the primer but have never seal. Is there problems with doing it this way?

No I used sheet metal 2 part weld on it which is suppose to hold and then a little spot putty. I'm building it to just cruise it this year seen I sold my 69, The body is coming off this next winter to get a new frame and 1 piece floor.

I just decided January to put this project on the road, so far we (me and my daughters)got the brake conversion p/d /b new bushings,new brake and fuel lines and a complete front suspension with the 496 in placed back with a m-20 and hoping to have paint on it by Satuarday

is it a Laquer primer?
I did that once, it wrinkled up just like that, when i topcoated, the solvents in the basecoat actually reacted with the primer

No its urethane primer and the paint on the car is omni paint, so when I bought the paint I bought the same brand.

if you welded it heat will do that,,,best to go to metal again

Looks like a good old chemical reaction. I would take it down until no trace of the reaction remained, then spray it with 2k primer/sealer. Try to spray the primer dry, thin, and dusty. You want to keep the wetness to a minimum until you have a solid coat of primer all over the area, then you can get a little more aggressive. Once you break through to the old paint this kind of thing sometimes happens. You may still have a lifting/reaction problem as you try to repair it. Hopefully not. Just keep working it. Get a solid sheet of primer/sealer over the area any way you can. Good luck.

A classic case of lifting. The solvents from your primer went under the edge of the old paint and reacted causing the lift. Take a DA and take the whole area down to metal and feather edge the old paint. The heat from the welder didn't help any here either.

You will want to remove any trace of cracked paint. You also want to feather the repair with a fine grit sandpaper. The finer grits will leave a smaller grit scratch vs a coaser grit, with the small scratch there is less area for any solvent to attack and recrack.

I would do any final sanding with something around 600 grit.

Also the best barrier to help prevent future cracking is epoxy primer. Epoxy is an excellent solvent resistant product, urethane can wick solvent. Spray 1 coat of epoxy straight do not mix in reducer. Spray it dry but NOT DUSTED on, dusted on will yield no affects.

You show another perfect reason as too why I hate OMNI, it can be a bear to fix. Cheap paint yields cheap results.

Also tinting primer with basecoat is a BIG NO NO, you can only tint with pure tints off a mixing bank not mixed basecoat!!! that would be another big problem...Eric

Eric, Can I ask why you cant add a paint stick of base into primer? what does it do other then give you a closer color of the base? I've never had any problems thats why I'm asking. I got out of painting back when b/c came in to the picture, but still paint one or two cars a year

Eric, Can I ask why you cant add a paint stick of base into primer?
I dont know of any paint manufactor that allows basecoat to be used as the tinting additive. If you want to tint you need to tint with the pure tints off the bank.
A PPG rep once told me the added resins in the basecoat effect the primer chemical makeup. He said a few things can happen but adhesion and durability(as in rock chips) were the biggest.

Thanks!