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I stripped paint off this nonferrous metal mailbox, then applied oil based primer:

enter image description here

I would like to paint the mailbox the same paint (color/sheen/grade) as the rest of the house, visible above it. I know that red-ish paints require gray primer and this is white. Will this red-ish paint be appropriate for this primer or should I pick a color that will?

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The only difference is that a red paint will "seem to cover" a gray primer somewhat more easily than a white primer. That is, it will take fewer coats to make it look good.

All paints allow a certain degree of "print-through". That is, if you painted a checkerboard with 1 coat, you could still see the checkerboard pattern. That is just a practicality of how paints are made. The answer is more coats - with enough coats, even the checkerboard would be hidden.

In a perfect world, you make the primer exactly the color of the topcoat. It will print through just as badly as the checkerboard. But you won't notice! LOL!

So that's what the gray is all about. Color has 3 traits:

  • Hue
  • Lightness
  • Chroma (saturation)

Lightness tends to be what prints through strongest, so the goal with gray primer is to get the lightness closer. So that print-through will be less obvious.

For instance, I have both white and gray primer in one paint system. When painting yellow, I mix the primers about 6:1 (a little gray goes a long way) giving a light gray, probably a Munsell 9/ in lightness. (0-10). It works better with the yellow than white does.

Red is particularly difficult, since good pigments are Just Not Available anymore. You probably don't want cinnabar, since it's mercury. So reds tend to be worse than average with print-through.

So, what does "more difficult" mean? It simply means more coats to get good coverage.

Overcoating will work, provided you follow the manufacturers' instructions regarding compatibility and cure times.

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  • so bottom line, do you think i should choose another color (e.g. blue) that fits on a white primer or it would be good to proceed with red?
    – amphibient
    Sep 25 '21 at 17:40
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    Sorry, I guess I left off the conclusion @amphibent. As long as you're willing to add a 3rd or 4th coat as needed, you can paint any color you want over white. Sep 25 '21 at 18:02
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It should work okay as long as the primer is fully cured.

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  • what does "fully cured" mean/imply?
    – amphibient
    Sep 24 '21 at 16:11
  • What does "should work OK" mean? Will red look sufficiently red over a white primer, or will the color appear to be different than the red on OP's house because it was (presumably) over a grey primer?
    – FreeMan
    Sep 24 '21 at 16:15
  • The word "cured" means that the chemical reaction that hardens a resin or paint has finished taking place. It is similar to the word "dried", but that strictly refers to water based paints.
    – Joe Blowe
    Sep 24 '21 at 17:09
  • It "should work OK" means that it should work well enough.
    – Joe Blowe
    Sep 24 '21 at 17:11

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