Article: Hair shine and sunscreen safety

Q & A

Cosmetic CONUNDRUMS

Q What causes hair to lose its shine after permanent hair dyeing?

A Virgin, newly grown, unprocessed hair contains a natural hair conditioner manufactured by the body, known as 18-methyl eicosanoic acid (18-MEA).

18-MEA is covalently bonded to the hair shaft as a monolayer of branched fatty acid with highly hydrophobic properties. This layer resists the entry of water into the hair shaft and adds shine. The ammonia and hydrogen peroxide present in all permanent hair dyes removes this 18-MEA layer from the hair shaft.

Removal of the 18-MEA can be likened to placing rubbing alcohol on the wood finish of a fine walnut table. When the rubbing alcohol removes the ...

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