diluting DEET?
Ben Crowell
and lightweight form to carry. Folks here have suggested applying it
either with an atomizer or by using a fold-top baggie as an applicator.
Is it water-soluble, so that you could dilute it to 25% while you're
on the trail? It seems like you could save a lot of weight on a long
trip by diluting it, since people seem to say that
25% is just as effective as 100%. If I was going to dilute it, I guess
I'd need to find a polyethylene container to do the dilution in
(maybe an old DEET container, if I can find one).
Or is dilution pointless, since you'd just apply more of the diluted
stuff?
hlil...@juno.com
Concentration affects duration of protection and how well it protects
against bad infestations.
"DEET-based insect repellents are available in a range of
concentrations from5 percent to 100 percent. A 5 percent product will
provide approximately 90 minutes of protection and a 100 percent
product approximately 10 hours. The "effective" time increases as you
increase the concentration of DEET.
"Generally, the longer you are outside, the higher the concentration
you should use. Higher concentrations also are recommended for all
outdoor activities in regions with large populations of biting insects
or ticks. Other factors are the type of activity and geographic
location. The EPA has determined that, when label instructions are
followed, all concentrations can be used by individuals of all ages."
http://www.deetonline.org/faq.php#q9
Ben Crowell
Interesting -- thanks!
So on the one hand you do get somewhat higher bang for the buck with
more dilute stuff. Diluting it from 100% to 5% would make your supply
last three times longer:
(100/5)x(1.5 hrs/10 hrs)=3
On the other hand, it would be more of a hassle to have to do the
dilution in the field, and apply it more often.
I'm thinking that the dilution might make sense on a long trip where
you basically intended to keep moving every day, all day, without a
lot of stops. In an area that's not too wet, I usually find that the
bugs don't bother me as long as I keep moving. The main time I really
need DEET is in the evening.
I guess this also depends on how much you intend to apply. Ryan Jordan,
in Lightweight Backpacking and Camping, claims a 0.2 oz bottle of DEET
can last for 2 weeks. I dunno, this seems like an awfully small amount
to me.
hlil...@juno.com
<crowel...@lightSPAMandISmatterEVIL.com> wrote:
If you can even effectively dilute it. I'm pretty sure Deet is
organic which means it won't mix well with water. It probably will
mix with alcohol and maybe the combination will then mix with water.
I'd at least try it before heading out and depending on that working.
Otherwise you could get a bottle with Deet on top floating on the
water on the bottom much as oil floats on water.
Ben Crowell
> If you can even effectively dilute it. I'm pretty sure Deet is
> organic which means it won't mix well with water. It probably will
> mix with alcohol and maybe the combination will then mix with water.
> I'd at least try it before heading out and depending on that working.
> Otherwise you could get a bottle with Deet on top floating on the
> water on the bottom much as oil floats on water.
Yeah, that's what I'm worried about. This fact sheet
http://npic.orst.edu/factsheets/DEETtech.pdf
says its water solubility is ">1 g/L," and mentions diluting it with
ethanol on p. 5. I don't understand why the solubility is given
as a > rather than an =. The only diluted form of DEET I have around is
some REI-branded Jungle Juice, which says "other ingredients...75%" on
the label.
If the only way to dilute it is with ethanol,
then obviously the idea of diluting in the field is
not a way of saving weight, since you'd have to carry the ethanol.
Well, I suppose there are other reasons for bringing some ethanol
along :-) I guess I could do experiments to see whether it's
soluble in a mixture of ethanol and water, but the thing is that
DEET is nearly colorless, so it might not be so easy to tell
whether it was mixing or not. I wonder how chemists determine this
kind of thing? Some of my co-workers are chemists (I teach physics
at a community college), so maybe they can tell me something useful.
peanut gallery
I've been mixing 100% DEET with a little water for years and it works
fine. The trick is to mix it just before applying. To do this I pour a
little water in one hand, add a few drops of DEET out of the bottle,
rub both hands briskly together to mix it well, and then while
they're still wet I apply it wherever I want it. If I just need a
little I'll mix the water and DEET in the cup of one hand and stir
vigorously with a few fingers, then use those fingers to apply it.
Don't skimp on the water. It makes it easier to spread the DEET over
large areas of skin and will evaporate quickly enough, leaving only
the DEET.
It doesn't need to dissolve into the water for this to work. A bunch
of microscopic beads of DEET suspended in water will still do the
job.
Ben Crowell
> I've been mixing 100% DEET with a little water for years and it works
> fine. The trick is to mix it just before applying. To do this I pour a
> little water in one hand, add a few drops of DEET out of the bottle,
> rub both hands briskly together to mix it well, and then while
> they're still wet I apply it wherever I want it. If I just need a
> little I'll mix the water and DEET in the cup of one hand and stir
> vigorously with a few fingers, then use those fingers to apply it.
>
> Don't skimp on the water. It makes it easier to spread the DEET over
> large areas of skin and will evaporate quickly enough, leaving only
> the DEET.
>
> It doesn't need to dissolve into the water for this to work. A bunch
> of microscopic beads of DEET suspended in water will still do the
> job.
Aha!!! Usenet at its best! This is exactly the information I needed.
I also found out that commercial formulations of DEET use ethanol as
a solvent. For people who don't mind carrying the extra weight of
diluted DEET, you can save a significant amount of money by buying
it at 100% and then diluting it yourself at home.
Has anyone here tried permethrin? How do you apply it to your clothes?
The wikipedia article makes me worry about the ecological aspect
of using the stuff.