[rotorwrench]

You can also use a conversion coating before priming. On steel I use Ospho. I always wipe my stuff down with prep sol before I shoot it and have never had a problem with condense. I don't completely agree that there will be differences in temperatures of materials due to different compositions. So if you move a project from the shade out into the sun, then it might condense a bit before it equalizes in temperature but it doesn't take long to heat up down here in south Texas. If you use a paint booth then stuff should stay at equal temps.

Capillary action can hold moisture in the joints between pieces of overlapping metal but it will dry out if a person hits it with compressed air several times and allows a dwell time before prepping to shoot the primer. I have never shot material over something that was wet with water before wiping or spraying it down again with prep sol and letting it dry out.