[pct-l] Deet

[jerrygoller at backpackgeartest.org (Jerry Goller)]

Interesting. According to the military's own research, concentrations of
DEET above 30% did not increase effectiveness. What did increase it was
timed release. The military developed a polymer based controlled released
formula that successfully addressed the break down issue and is available
commercially as 3M Ultrathon (just over 30% concentration) in both a cream
and a spray. Sawyer Controlled Release is a similar product with a
concentration of about 20%. 

The reason that 100% appears to work better is that DEET starts to break
down as soon as it is applied to the skin. It continues to break down until
it completely loses it's ability to repel, which is below 20%. Obviously, it
takes 100% longer to break down than it does 30%.

With controlled release DEET the DEET is encapsulated in a polymer at
"protects" the DEET molecules from breaking down. The polymers are
formulated to break down at different rates therefore allowing a constant
concentration of between 20 and 30%, depending on the brand, over a much
longer time period. Protection over 12 hours or greater is very common. I
only apply it once a day. 

Now I will agree that in very high concentrations of particularly aggressive
mosquitoes it is possible that augmentation with 100% concentration could be
beneficial. I've not run into that yet, but have read about it.

This system last longer than 100% DEET, is resistant to dilution by
sweating, is much more comfortable to wear, and it also tends to limit
dermal absorption of the DEET. 

We tested both products on BGT.

Jerry


http://www.BackpackGearTest.org : the most comprehensive interactive gear
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-----Original Message-----
From: pct-l-bounces@mailman.backcountry.net
[mailto:pct-l-bounces@mailman.backcountry.net] On Behalf Of Richard Woods
Sent: Wednesday, February 08, 2006 8:47 AM
To: pct-l@mailman.backcountry.net
Subject: [pct-l] Deet

I completed a maritime survival course in Alaska (I Survived in '85).
One topic was insect repellent.
One fact I'm sure of is that the effectiveness of Deet-based repellents
coincides with the percentage of deet in them. In Alaska, where mosquitos
should have fuselage numbers, the only truly effective repellant is 100%
deet. From personal experience, don't bother with cans, creams, sprays, with
anything less than 100% deet.  
Typically comes in a four-ounce bottle. Yes, this is the stuff that
dissolves plastic, and has a really nasty odor. However it does last and is
also effective against ticks, and, to lesser extent, deer and black flies if
I remember correctly. As I'm sure you all know, it has to be used carefully,
and has some significant downsides. Also the usual disclaimer applies: what
works for me might not work for you and verse-vice-a.

Last summer, my very unscientific personal comparison test of two types of
repellents ended voluntarily by the end of the first day on the trail. I
compared the effectiveness, for me, in the local conditions, and at that
level of exertion for me, of 100% deet and Cutter Advanced (Picaridin)
lotion. First I tried this new Picaridin- based lotion. Seemed to be
effective for about an hour, except that it came off wherever I was
sweating/chafing. However, by the end of the day, I was moving faster than I
wanted to, just to stay ahead of the clouds of mosquitos in pursuit of my
warm, sweaty, CO2-producing carcass. They caught up with me just in time for
dinner, and I relented and slapped on some 100% deet so I could finish
dinner and retreat into my tent. I gave away the Picaridin lotion to a SoBo
section hiker who had forgotten his at home. A little protection is better
than nothing.


On Feb 7, 2006, at 11:29 PM, pct-l-request@mailman.backcountry.net
wrote:

> I'd like to know what type of Deet of special formula they were using 
> in the "Grizzly Man" film.  The bush pilot never even flinched, but I 
> was swatting them away in my living room!  Maybe that's what drove 
> Treadwell mad.
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