Auto body repair & detailing: clear coat, air filtration system, diaphragm type

Question
Hi, can I use an iwata lph400 (tip 1.3)to base coat and clear? I've been using it for both and the base goes on fine but the clear doesn't look good. the care ends up looking like a "teflon frying pan" very interesting look almost like a powder coat. Anyway the clear directions say use 5-9 psi but it seems that at 40 psi it looks better. Any advice would be great, thank you. Sincerely, Dan Cory . Columbus Ohio

Answer
Dan, it could be a lot of things going wrong here. If you're using a fast dry clear, they are inherently high in orange peel. It's a give and get sort of thing. They do great on one or two panels on a 75 degree day, but during the summer- well, I suggest a slow clear in warm weather. Also, go up to a 1.5 tip. I like having too much fluid- you can always cut back fluid, but once it's flow is maxed, you just can't get any more paint to come out. Do you have a pressure gauge on the head of the gun? That's what they mean by the pressure being 5-9 PSI at the head or cap. The pressure on most guns is different at the cap than at the gun. Are you using a cheater valve, or a true pressure regulator? Cheater valves on a spray gun screw up volume of air- that is the whole ball of wax with a High volume, low pressure gun (HVLP). A diaphragm type regulator reduces pressure while allowing maximum air volume at that pressure. Air fittings can also mess with air volume- there are large diameter air hose chucks and hose fittings that are twice the diameter of regular air tool fittings. You need to be sure they are fitted onto BOTH ends of the air hose. What sort of air filtration system do you have? You can't beat a desiccant drying system for the money. Humidity and water vapor from the compressor will reduce flow. Now, putting all this aside, if you get better results at a little higher pressure at the cap- I say go with it for now. You are compensating for one or all of these aforementioned flaws in the paint delivery system. I do think, however, that with some money and diligence, you can make your paint lay better with the equipment upgrades I suggested here. If every problem reduces flow 10%, and there's 5 problems with your paint system- well, do the math. Bill