Re: What exactly are terps doing?
Posted by Catherine Cartwright Jones on August 8, 2002 at 16:40:42:
: hennotannic acid molecules which facilitates such fast and profuse
: dyeing of keratins?
As far as I can tell (taking deep breath here, with a caveat the size
of a medium dog):
Because lawsone is hydrophobic, it will dissolve readilly in a
monoterpene alcohol, therefore you get far more of the lawsones
available to penetrate and bind with the keratin. The acid breaks
down the vegetal matter and faciliates dye release, then the
monoterpene alcohol facilitates lawsone availability. Therefore, MORE
lawsone is made available to enter the skin cell.
The monoterpene alcohol reacting with the lawsone within the skin
cells contribute to more rapid and deeper level oxidation and
darkening than can be achieved without monoterpenes under the same
conditions of temperature and time. Perhaps the alcohols are
evaporating and oxidizing the lawsones as they go. Therefore, terped
henna gets darker than unterped henna, over the 72 hour period
following application, and this is particularly visible in the upper
layers of the stain.
Contrary to prior perception, monoterpenes do not contribute to a more
shallow henna penetration. Unterped and terped henna stains in a
comparison test disappered on the same day.
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