Auto body repair & detailing: Clear coat problems, types of solvents, grease remover

Question
I'm having some problems with clear coating, I'm working on my 3rd attempt. Ever time I spray the clear I get these little bubble looking things. When I wet sand it the bubble things turn into little white specks that look like overspray. I have a water trap/filter at the tank and on the base of the gun. I double checked the measurement of the clear. It's correct.After the 2nd time I thought that maybe the gun had some old paint left in it, so the 3rd time I used a new gun, that has never been used. the temp. outside has been in the upper 70's to 80's. The gun that i'm using is a HVLP, and the regulator on the gun is set around 10-20psi. Please tell me what I'm doing wrong, and if I can fix it without having to sand the clear coat off again.

Thanks, Zach

Answer
Are the little bubles coming up after the clear has been applied or while you're appling the clear? What is the ambient temperature? What is the humidity level? What clear are you using? It sounds like it could be fisheyes or solvent pop. If it's happeng while you're applying the clear, it's probably fisheyes. This is a contamination on the vehicle problem, and can be corrected by washing with soap & water followed by a solvent cleaner (wax & grease remover). you will have to sand past the fisheyes, where they are removed completly - clean correctly, reapply color and clear. If the problem is solvent pop, this is a problem where the solvents were'nt allowed to flash (evaporate) before subsquent coats were applied. This traps solvents in the lower coats, when they finally evaporate they bust through the very top surface of clear which has started getting hard allready. This can be caused by; too high a temperature for your clear, not enough flash time between coats, too low air pressure, coats being too wet, and high humidity makes it worse. Clears have two types of solvents; flash & transfer. The transfer solvents evaporate on the way to the car, and the tail solvents evaporate after the clear has been applied (this leaves the film wet enough to allow all of the clear to be applied without getting dry spots. If your gun is too close to your work, or air pressure is too low it will trap the transfer solvents which causes the clear to skin over rather quickly. This traps the tail solvents, and when they do evaporate it pops holes in the finish. The only way to repair solvent pop is to sand past the affected area, reapply color and clear. The white specks sound like the wetsand residue in the fisheyes or solvent pop. When you wetsand clear the residue is white, this gets into the low areas (pinholes from solvent pop, or craters from fisheyes) and looks like little white specks. You will have to sand past those, or it will never go away. No matter how many time you clear it won't go away until they are removed completly. I hope this helps, if not feel free to call me 910-362-7582 M-f 7:30-2:30 eastern. Also 10 to 20 psi on a hvlp gun is a wide range, pressure shouldn't fluctuate more than just a couple of psi to keep the finish even.