Re: To CCJ

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Posted by Catherine Cartwright Jones on August 27, 2001 at 17:29:25:

In reply to: To CCJ posted by Lurker on August 27, 2001 at 16:52:07:

: I read somewhere that Henna releases it's dye before application to
: the skin, ( I understand that is why it's left overnight to "brew"
: with the lemon in it) If this is correct, why does no-one extract
the
: dye out in a liquid form that could be painted straight on to the
: skin and presumably would soak in and stain almost instantly, and
: forgo the paste bit. I realize that if this were possible it would
: already have been done, so why is it not possible, what nasty bit of
: chemistry prevents this from being done?

Hennotannic acid combines with oxygen on contact and changes ..and is
no longer useful as a stain. Therefore extraction is not helpful.

Also, the dye, Lawsone, in its pure form, is toxic on skin. Henna
dye is best kept mixed in henna, greatly diluted in the vegetable
matter. There are also many other compounds in the henna leaf, which
have excellent and usful properties, and are worth keeping.

The best way to get the dye available and ready to go on skin is to
mix the henna with an acid (to release the dye and retain the -h out
on the side of the second carbon ring) and do that in an inert
atmosphere (nitrogen for instance) to keep the acid from oxidizing.
Then ... some form of terpine of an -ol character may be added to the
paste hasten the oxidation once it's put on skin. This is PRECISELY
how many of the pre-made pastes are made, and its quite safe and
efficient.

Who are you?

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Re: To CCJ Lurker 20:37:12 8/27/2001 (0)

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: : I read somewhere that Henna releases it's dye before application to : : the skin, ( I understand that is why it's left overnight to "brew" : : with the lemon in it) If this is correct, why does no-one extract : the : : dye out in a liquid form that could be painted straight on to the : : skin and presumably would soak in and stain almost instantly, and : : forgo the paste bit. I realize that if this were possible it would : : already have been done, so why is it not possible, what nasty bit of : : chemistry prevents this from being done? : : Hennotannic acid combines with oxygen on contact and changes ..and is : no longer useful as a stain. Therefore extraction is not helpful. : : Also, the dye, Lawsone, in its pure form, is toxic on skin. Henna : dye is best kept mixed in henna, greatly diluted in the vegetable : matter. There are also many other compounds in the henna leaf, which : have excellent and usful properties, and are worth keeping. : : The best way to get the dye available and ready to go on skin is to : mix the henna with an acid (to release the dye and retain the -h out : on the side of the second carbon ring) and do that in an inert : atmosphere (nitrogen for instance) to keep the acid from oxidizing. : Then ... some form of terpine of an -ol character may be added to the : paste hasten the oxidation once it's put on skin. This is PRECISELY : how many of the pre-made pastes are made, and its quite safe and : efficient. : : Who are you?
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