Having my car repainted right now, 84 Z28 and the paint shop tried to spray my. Front bumper two times now and every time they go to bake it at all cracks ... but the rear bumper came out fine .....anybody else having this issue

 

It sounds like there are cracks in your plastic bumper cover. I posted a video on how to repair those- do a search and you should find it. It involves grinding them clean and plastic welding them. Not a small task, but what is needed if you want a proper fix. GOOD LUCK!

 

Might check your dealer for a NOS part. GM had 17 new ones in a MI warehouse for my 89 Camaro.

 

Then don't bake it. I've repainted a fair amount of flexible bumpers, never once used a flex additive and I've only experienced one crack. The crack occurred because I accidentally twisted it when one side slipped from my hand.

 

Weird. The cure cycle in our booth only runs at 145 degrees for 28 minutes. A black car in the sun on a really hot day probably gets a LOT hotter than the painted parts in the booth....especially since the cure cycle doesn't run that long. My gut feeling is if it's doing it during the cure cycle, its gonna do it in the sun, too.

Just curious....are they using solvent base paint, or water base?

Find out what they did different between the front and rear bumpers......if there are more paint layers from previous repaints, etc. If you have cracks in the plastic itself....you will see them as soon as you spray sealer over it. You'll know they are there WAAAAYYYYYY before it's all done and in a cure cycle. But I have no idea how far the paint is stripped down, etc.