Help! Omni MBC Lifts Omni clear coat!

[Guitar Charlie]

Hi,

I was finishing up a bumper (front plastic, Honda Civic) and noticed that I missed a spot on the edge with PPG Omni color, I thought I got everything and already cleared it with PPG MC 262. So, I mixed up some color and went back and sprayed the edge of the bumper that still showed the faint gray primer. As soon as the Omni MBC color hit the bumber the Omni MC 262 clear started lifting and bubbling up. What can I do? Should I re-prime (epoxy or NCP 270 sandable) the bumper and start all over? This is really frustrating because I was done except one little spot that I wanted to touch up and now it looks like I might be back to square one, any thoughts?

Thanks,

Charlie

[Phil V]

Charlie, the problem is you used a non catalyzed basecoat paint. I ONLY use catalyzed basecoats (mainly PPG DBU with the DRR reactive reducer). If you had used a catalyzed basecoat you would never have a lifting problem.

Your best bet at this point is to shoot a couple light coats of 2-K high build primer after wetsanding out the lifting/peeling area. You will have to scuff the whole bumper cover after you spot in the new basecoat color.

[Chris L]

Phil are you saying that a catalyzed basecoat wouldnt react on top of allready sprayed wet bed of CLEAR COAT?I use matrix,and i have had to dig out a bug or two and recoat with base,it never wrinkles,but always makes a halo or makes the clear look like it died back.I did however do it recently,and it let the clear dry about an hour,resprayed my base over it,then recleared and it came out fine.

[Phil V]

Chris, no - what I was saying is that if Charlie had used a catalyzed basecoat to start with then the paint wouldnt' have lifted when he tried to recoat with more base later.

If the clear he applied on his bumper cover the first go around was applied so that it fully covered the omni basecoat then the paint would not have lifted later either. ( when an uncatalyzed basecoat is fully covered with a coat or two of clear then that clear for all effective purposes works as a barrier coat isolating the basecoat under that clear keeping any new basecoat from reacting with the previous basecoat).

Actually Charlie made two mistakes (pointed out for illustration purposes only, not flaming Charlie). The first mistake was not using a catalyzed basecoat and the second was not putting enough clear over that non catalyzed basecoat to seal the base under that clear.

[rjp73]

So...let me see if I understand this. I too have a few spots that didn't cover correctly the first time around. After sanding the clear with 1000 wet paper I was going to apply more base color and reclear. If sanded through to the base in a couple of spots ( Omni non-cat!) , can I shoot some more clear on those spots and then re-base to avoid the lifting?

[isprayum]

theres one major rule to this respraying thing here. if you respray very lightly. and i mean very light, let it flash, spray a lil more, let it flash. I believe you can ALWAYS avoid lifting with light coats. once the light coats have covered the spot and flashed good, then you can go heavier to even out the color. if you respray anything too heavy, it will probably lift. especially over fresh clear.

[Guitar Charlie]

Thanks for the help. I guess I never encountered this before because I always used the catalyzed base coat but my friend did not want to spend the extra $ on paint and bought the OMNI which turns out to be the shortcut that took the long way around.

Won't I have to prime the whole bumper to avoid this from happening again or just spot priming the effected area work because the clear had more time to cure?

Thanks again,

Charlie

[Phil V]

Spot prime the affected areas where there is basecoat showing with little or no clear.

[wolfsautobody]

Phil are you saying that a catalyzed basecoat wouldnt react on top of allready sprayed wet bed of CLEAR COAT?I use matrix,and i have had to dig out a bug or two and recoat with base,it never wrinkles,but always makes a halo or makes the clear look like it died back.I did however do it recently,and it let the clear dry about an hour,resprayed my base over it,then recleared and it came out fine.

Could this have also occurred because he put the base on top of the clear before it had time to dry? I had a problem with DBU one time where I did pretty much the same thing happen. And it wrinkled on me too.