Well here is what I remember for chemistry class years ago.

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Posted by Faery Ring on April 10, 2001 at 19:00:40:

In reply to: Re: Interesting! posted by Catherine Cartwright Jones on April 10, 2001 at 15:13:16:

Well here is what I remember for chemistry class years ago. There
are two types of molecules: polar and non-polar. The most common non-
polar liquid is water. Then there are polar liquids like oils and
ether. They are opposites, which is why oil and water don’t mix. So
the rule is non-polar substances such as sucrose (table sugar) would
prefer to dissolve in non-polar solvents (water) and polar molecule
prefer polar solvents. Unfortunately this is not a hard and fast
rule (it really depends on the molecule in question). Alcohol tends
to exhibit properties of both.

The lawone molecule is supposed to be insoluble in water but it is
soluble in ethyl alcohol (grain alcohol) and ether. So you would
think that if you added a little ethyl alcohol that it would help to
dissolve the lawsone dye in the paste but it is not so simple. I
have found that my experiments with ethyl alcohol are that it doesn’t
stain the skin very well. %100 water works better for some reason
then a water ethyl alcohol mixture. The biggest problem is that
water penetrates the stratum corneum (dead skin cell layer) better
than most other solvents. Terpenes are polar molecules that may
transfer the lawsone molecule into the skin faster. Terpenes are
small enough to penetrate the dead skin cells unfortunately they can
cause irritation. However, things get more complicated because
terpenes such as camphor carry an oxygen molecule that may oxidize
the lawsone molecule causing it to turn browner faster then with
exposure to air.

So that’s my hypothesis. I haven’t done enough research on the
subject. I hope to test camphor and menthol and I would like to try
to test some propylene glycol instead of ethylene alcohol.
Unfortunately I don’t have much time to dabble in these sorts of
experiments.

Faery Ring

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: Well here is what I remember for chemistry class years ago. There : are two types of molecules: polar and non-polar. The most common non- : polar liquid is water. Then there are polar liquids like oils and : ether. They are opposites, which is why oil and water don’t mix. So : the rule is non-polar substances such as sucrose (table sugar) would : prefer to dissolve in non-polar solvents (water) and polar molecule : prefer polar solvents. Unfortunately this is not a hard and fast : rule (it really depends on the molecule in question). Alcohol tends : to exhibit properties of both. : : The lawone molecule is supposed to be insoluble in water but it is : soluble in ethyl alcohol (grain alcohol) and ether. So you would : think that if you added a little ethyl alcohol that it would help to : dissolve the lawsone dye in the paste but it is not so simple. I : have found that my experiments with ethyl alcohol are that it doesn’t : stain the skin very well. %100 water works better for some reason : then a water ethyl alcohol mixture. The biggest problem is that : water penetrates the stratum corneum (dead skin cell layer) better : than most other solvents. Terpenes are polar molecules that may : transfer the lawsone molecule into the skin faster. Terpenes are : small enough to penetrate the dead skin cells unfortunately they can : cause irritation. However, things get more complicated because : terpenes such as camphor carry an oxygen molecule that may oxidize : the lawsone molecule causing it to turn browner faster then with : exposure to air. : : So that’s my hypothesis. I haven’t done enough research on the : subject. I hope to test camphor and menthol and I would like to try : to test some propylene glycol instead of ethylene alcohol. : Unfortunately I don’t have much time to dabble in these sorts of : experiments. : : Faery Ring
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