Friday, April 25, 2008

A Lesson In Solvent Pop

I wheeled the MR2 out of the garage and looked over the bumpers. The front bumper looked like crap. Lots of sanding scratches under the basecoat. A huge run was on the lefthand end. And there were lots of teeny "craters". I probably could have lived with any one of the three, but the three combined, made a respray necessary. So I got out my 400-grit eraser and went to work...

When I shot the bumpers I was super, super careful at controlling the dust. I even shot without the fans on. I laid the basecoat down, inspected carefully for dust - none. I laid the first coat of clear down, inspected carefully for dust - none. I laid the second coat of clear down and had "dust nibs" everywhere! This can't be right I thought to myself.

My friend JP suggested the possiblity of solvent pop. He asked how thick I was laying out the clear. I was laying it on about as thick as I could get it and not have it run. "Too thick!" he suggested. I took this photo of my roof when I painted it in December.

Some time spent with google yeilded this this this webpage. The pic at the bottom of the page looks like it could have been from my car!

I setup an experiment with the valence that goes underneath the front bumper. It's not visible, so I wasn't too concerned with small defects. I painted the right hand side using thin coats of clear. I painted the left hand side using thick (as before) coats. Sure enough, the right hand side came out great, the left hand side had "craters". Lesson here, don't lay out the clear too thick, it will solvent pop. There were still some tee-small dust particles, but nothing very significant. They will probably come out with a good buffing. Had I known this before I could have saved a lot of work wet sanding the body. Live and learn!