[kaw550]

What effect will different color primers have under red?

I was told gray is the easest to cover.
Red would require less paint
white would make it "pop"
..............................................

[baddbob]

You want full coverage or to end up with a color that is equal to full coverage. Some reds really suck for coverage while others cover in two coats. A grey that is equal to your red in black and white shades (the same in terms of darkness) will cover well. A white undercoat will add brightness if full coverage isn't achieved but will also make for some piss poor repairability. Dark undercoats will add darkness to the color if full coverage isn't achieved but will also make for piss poor repairability. Dupont's valueshade system for determining what shade of grey is needed can help you determine which sealer to use, have a dupont supplier look your color up and tell you what valueshade undercoat is suggested. Do a sprayout testpanel with 5 coats of base over your sealer to determine when full coverage is achieved-tape off a panel and spray one coat let it flash then move the tape down exposing more of the panel, spray another coat then repeat untill five or six coats have been sprayed. Then look at each coat in steps to determine which coat produced no change and you'll then know how many coats you'll need. Or shoot a black and white testcard while you spray the car and cross your fingers that you've bought enough paint.