On 12 Jun, 2005, at 23:11, Jeff Frye wrote:
I should have posed this question a few weeks ago when
we had the thread going. Anyway, what's the use of
having a bunch of chemists sitting around if you don't
tap the knowledge. I have some small bottles of 100%
DEET. That concentration scares the heck out of me.
What could I cut this stuff with (water, alcohol..)and
in what ratio and still provide effective coverage? I
always take the usual precautions, getting about 20
yards downwind from my gear when applying and washing
and sanitizing my hands before touching flyline.
Thanks in advance for your help.
Err, what's the question exactly? I have a large bottle of 100% DEET
(direct from a chem supplier) and it doesn't scare me one bit ;-) Is
it the toxicity that scares you? If so, a 5 fold difference in
concentration (20% vs 100%) doesn't make a whole lot of difference,
i.e. if the pure stuff would be dangerous, a 20% solution would only
be slightly less dangerous (and yes, there are exceptions, things
that have a very, very steep dose-effect curve).
The general understanding with DEET's repellency to biting critters
is that the concentration of DEET in the lotion that you put on your
skin does not so much influence potency as it does longevity. DEET
preparations from 10-20% up are effective against mosquitos; stronger
solutions (which usually equates to more DEET on the skin after the
solvent has evaporated) just last longer. For efficacy against ticks,
you need stronger solutions (i.e. more DEET), same with no-see-ums
(Ceratopogonidae, Culicoides). Anyway with no-see-ums the repellent
effect only lasts for an hour or so, and while DEET will stop them
from biting for a certain period of time, it won't stop them from
flying into your hair, nose and ears, and generally being a bloody
nuisance...
For general topical application, medicinal (i.e. non-denatured)
alcohol (ethanol) is the best solvent. If you want to treat your
clothes (you'd need a large supply of DEET then) you can make an
emulsion with water. A general use solution would be 20% (1 part
DEET, 4 parts alcohol), although I usually make 50% solutions.
And yes, keeping all this far from any PVC or ABS is very, very wise.
For in-field use, put the stuff in a pump spray bottle so that you
can apply it without actually touching the solution with your
fingers, as you would have to when it is in a standard squeeze
bottle. Or get Airflo fly lines ;-) (or silk of course).
Cheers
Henk
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| Dr. Henk J.M. Verhaar | e-mail:
[EMAIL PROTECTED] |
| Ecotoxicoloog en vliegbinder | tel: 035 656
2128 |
| Stichts End 17 | mobiel: 06 26
136034 |
| NL-1244 PK Ankeveen | web: www.xs4all.nl/
~flyrod |
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