What went wrong?

[Spychocyco]

So this isn't on one of my PBG builds, but another guitar I'm working on. Hopefully someone here has the answer so that when I sand this down and do it again, I don't have to repeat.

Before I put the clearcoat on this one, I couldn't really see these "dirty spots," (of course there were a lot of scratches from wet sanding) but once the clear was on, they popped up all over the place. I sanded the clear off in one spot which seemed to be the worst (pictured) and tried to sand the spots out, but it didn't really work, despite sanding a bit too deep on the corner, as you can see. Since I was looking at a complete sanding I hit it with clear again hoping for a miracle, but it looks even dirtier.

It's a rattle-can finish, but the same types of primer, paint and clear that I've been using on other builds, and this is the first time I've had this particular problem. Of course, it's also the lightest color I've ever tried to spray. My first thought is that the paint may have been a little too soft still when I did the wet sand, but I don't know.

[Sonic Mountain]

Might need some more pics. Is the finish kind of 'wrinkled' in that area? Or are we talking more about specks of dust or something?

[Simon Barden]

It's very hard to say. It's possible that the paint is reacting to some greasy finger marks, or as you suggest, the paint may not have been dry all the way through before you started sanding. The top layer can feel dry, but it can still be semi-liquid underneath that, resulting in a rough surface where the sandpaper breaks through the hard layer and into the soft.

In general, if it bubbles up, then it's a reaction to something, if it's pitted, then it's probably because the paint/lacquer wasn't fully dry.

I had a black-faced headstock that I needed to sand back. I'd put many layers of black spray on as I'd needed to build up some height with it. All done according to the manufacturer's recommendations, although by necessity using a lot more coats. The top layer was hard and firm, but underneath that, the bottom layers were still soft and sticky.

[Spychocyco]

Might need some more pics. Is the finish kind of 'wrinkled' in that area? Or are we talking more about specks of dust or something?

No wrinkling or bubbling. It really just looks like dirt or grease smeared all over it. I'm thinking Simon is probably right in that it's some sort of reaction with something, whether skin oils or something else.