Originally Posted by 69 widetrack
It may not be rust, but left alone it probably will be...bubbles or blisters in paint are usually caused by moisture...this moisture very often comes out of your compressor into your air line and out your gun...You may not see it when you paint and it can take years for it to show up as a blister or bubble. The only solution is, as you said to sand it down, polishing is not and option, it needs to be removed, repaired, and painted.
Sorry about that but that's what it looks like and usually it is.
I have to agree with Ray. But there is no telling exactly what it is until you cut into one of the bubbles. I know you do not want to do that. But something is going on.
As for rust, metal is very porous, and sometimes rust can be deep in the metal, you grind and clean off the surface. It looks good and clean but underneath that rust is there and it will travel up to the surface once again. I know cos I went through this when I restored my 66 Pontiac Bonneville. 2 years later the rust returned and I was so sure I got it all.
So I have been exactly where you are. Gorgeous paint on my car and as it was a candy, there was really no way to spot repair it.
If you want to know exactly what's going on, you're going to have to dig into one of the bubbles. You can try sanding it down. Use a hard block like one of Motor Guards Run Blockers. I use these all the time in cases where I have to sand something out and not get to too far into the surrounding clear. Maybe you'll be lucky and they sand out.
Good Luck. Hope its not rust but I think it just might be.