[hotrodf1]

Fellas,

My buddy and I are painting his mustang following a pucker up kind of guardrail incident. He has a Cobra style Cervini body kit for the car (new). I have limited experience with spraying plastic. Of course, used the plastic prep cleaner, and Bulldog adhesion promoter.

We sprayed a SEM brand flexible primer - you spray directly out of the can, no thinner, catalyst, etc. This stuff is IMPOSSIBLE to sand! Never have I ever spent 30 hours sanding a front bumper cover. The sandpaper (3M, other good brands) works only a little while, like for a small 6" square, then you have to reload with new paper. It is pure hell. We tried 180 wet, 180 dry, 400 wet, etc. The primer states that the maximum bending is 60 deg on a 1 1/2" radius - now thats FLEXIBLE!! Almost ridiculous.

I'm thinking we did not need this crazy primer ($34 a quart) to get these urethane pieces straight. They are pretty stiff - like OEM quality, very nice. And I do NOT want to have to go back through that again.

It seems a regular 2K urethane high build primer would be fine, right? The other Mustang I painted (mine at the time) was sprayed with it and I never had any issues, but the pieces were not off the car at the time, either.

Also sprayed some motorcycle fenders and side pieces, had to use special cleaner, adhesiion promoter, but they went fine with 2K primer, too.

ANyone have any thoughts on this?? We could sure use a break.
he's planning on keeping the car so we want to do it right, just not kill ourselves in the process.

[kenseth17]

never had any problems with regular 2k primer on urethane pieces. I normally use epoxy and if more fill is needed, I spray urethane primer on top. I don't regualarily use adhesion promotor either, but will once in awhile will. I've never noticed a problem with this. I believe the most important thing with urethane parts is to clean well, do a thorough job sanding, and reclean. In fact I seen a cavalier I put some urethane bumpers and skirts on. The kid totalled it not too long after he got the car back. Airbags blown, cracked windshield, front end was smucked in and the front urethane bumper lying loose and twisted to heck. That one I stripped the paint off to urethane cause someone prior did a poor sand job. I sprayed adhesion promotor on that one, followed by a coat of epoxy, and a few of urethane primer for a little fill and ease of sanding. I looked at the twisted carnage after the wreck, and there was only a small amount of paint was missing where it was really a twisted mess, majority of paint was unaffected. I believe flexible primer or flex additive is a waste of time-money. Wish I would of snapped a pic of it after wreck.

[hotrodf1]

Cool, thanks for the info. That goes along with what I was thinking as well.

I sure wish we would have known before we sprayed that crap and created such a waste.

oh well. not the first time I've learned things the hard way.

knucklehead. . . .