Sun darkens skin because it triggers the production of melanin, a brownish-black pigment that helps filter out harmful ultraviolet rays. It lightens hair because the UV light triggers the breakdown of these selfsame melanin molecules into simpler and evidently less colourful compounds.
The exact mechanism by which this is accomplished is not as clear as it might be. "The ionic pathway probably begins by nucleophilic attack of the peroxide anion on the o-quinone grouping," says one medical text, clearly written by the kind of faqer you wouldn't want to be stuck in a corner at a party.
The melanin in both skin and hair is meant to protect the other tissue, but in skin it's renewed (and thus the skin gets darker) whereas in hair it's not, since hair is no longer living.
The exact mechanism by which this is accomplished is not as clear as it might be. "The ionic pathway probably begins by nucleophilic attack of the peroxide anion on the o-quinone grouping," says one medical text, clearly written by the kind of faqer you wouldn't want to be stuck in a corner at a party.
The melanin in both skin and hair is meant to protect the other tissue, but in skin it's renewed (and thus the skin gets darker) whereas in hair it's not, since hair is no longer living.
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3 comments:
This is great to know. I couldn't understand why I had to dye my hair every 2 weeks this summer while tanning.. Now it makes sense! Donna G.
Very interesting. This has been a query of mine for sometime :D
So blonde, bronzed beauties are really just (sun)damaged goods :) Miaaooow
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