Originally Posted by dt196
I've had this discussion with my paint rep for several years. My contention is that coverage is coverage. I use the 1" square self stick targets that are black and white checkerboard colored when I paint. It's known as black and white hiding. When you can't see the black and white through your basecoat, then and only then do you have "coverage"
For example, say it takes 4 coats of a yellow base to get black and white coverage. If you use a sealer that is close to yellow, you may think you have coverage in say 2 coats. But do you? No, the sealer is influencing the color you are seeing. Doesn't matter if your sealer is lighter or darker, you still don't have the true color of the basecoat until you have black and white hiding.
A sealer that is close to the basecoat will make you think you have coverage before you really do. Now I'm not saying it's not a good idea to seal with something close in color to the base. It makes a lot of sense, especially when it comes to those stone nicks and door dings that you'll eventually get.
Just my .02
Dan I totally agree with you. Dupont's valueshade system helps get the poor covering Dupont formulas out the door, but when it comes time to do repairs on these jobs that aren't really covered it can be a PITA. Every paint company has coverage problems with some colors but Dupont has the most problems within it's premium lines. I worked in a Dupont only shop for awhile and couldn't believe how many poor covering mixes we had compared to the PPG systems I had used. And to top it off Dupont got to sell us the valueshade primer and sealers to make the products work. Dupont's valueshade system has always been shades of grey.
Nowadays, I do mostly restoration and custom work and usually shoot a 50/50 black and white test panel to verify coverage. I spray one coat, then mask and apply another, then move the mask and spray another..., so I end up with basically a letdown panel showing the difference in coverage on each coat applied. I've found some mixes taking five coats to reach full coverage! The last one that took 5 coats took two gallons of color for the complete job$$$$. When piling this many coats of base on it's really important to activate the base for good durability.
Dupont's basecoats spray easy but there really is a difference in quality, and coverage between different company's basecoats. I spray more Global than any and now Nexa is coming to this area and from what I here the coverage is good-we'll see. Bob