tips for spraying primer

If your spraying the whole car, did you take it all the way down to the metal?. I usually go through about 2-2 1/2 gallons of urethane primer, but i like to block it alot to make sure i have a flat and smooth surface. The air pressur depends, are you using a hvlp gun or a hvhp gun(regular suction gun). For the Gravity type i use about 20 psi-1.7mm tip, but you need to see what your gun requires. When I block I use 180 grit for the first and work my way to 400-600. When you are confident in you work, put a guide coat, or you can use some black spray paint and mist the panels, then wet sand it with 600 and look for any low spots where the black paint is still showing. If you got metal shining your high. You can use guide for any step of blocking you want. Personally i wont prime or paint nothing under 60-65 deg F. Causes a tendency for the paint to want to run and that sucks. Good luck.