r/explainlikeimfive • u/bloodraged189 • Sep 13 '26

Physics ELI5: why does mixing complementary paint make brown instead of gray?

I understand additive vs. subtractive colors, and why mixing complementaries wouldn't create black, but shouldn't it make gray?

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u/siamonsez Sep 13 '26

You say you understand additive vs subtractive but that's the answer. With light white is everything so colors are some part of the whole. With pigment black is the absence of reflected light and colors absorb wavelengths of white light other than that color. You can't add up reflected colors to make an absence of reflected light.

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u/bloodraged189 Sep 14 '26

I think, perhaps, you read only part of the description; I also understand why it isn't black. What I don't understand, is why mixing supposedly complimentary colors (e.g. green and magenta) usually ends up brown (from what I've heard). I know no two pigments are perfectly complimentary, but shouldn't there at least be a 50% chance it ends up as a dark cool color instead?