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DEET Dissolves Breathable Fabrics

Heavily Patched Hard Shell Pants
Heavily Patched Hard Shell Pants

I’m a skeptic by nature and have always questioned authority, standard operating procedures, gut feel, the status quo, and institutional knowledge. In work and at play, I often put these truths to the test by doing experiments or establishing quantifiable metrics that invariably show that long-held beliefs are grossly incorrect.

Does DEET Melt Synthetics?

I’d always heard that DEET dissolves breathable fabrics, such as Gore-Tex, and that you should keep the two from coming into contact with one other. I’ve never had this problem outdoors when I’ve used DEET, but I couldn’t pass up the opportunity to test whether it is true or a myth in a more controlled setting on a pair of breathable rain pants.

One winter, I managed to shred a pair of Mountain Hardware Cohesion Pants, slashing dozens of rips in the legs with sharp front points, while learning to use crampons. Mountain Hardware Cohesion Pants are made with Conduit DT, a proprietary Gore-Tex knockoff that has three layers: an outer shell layer made from Epic nylon, a middle breathable layer made from Conduit DT, and an inner Epic stretch liner. I tried to extend the life of these pants with duct tape (see above), but finally donated their remains to science.

DEET Concentrations

I applied three squirts of Ben’s 100% DEET and Ben’s 30% DEET to the Epic nylon fabric on the outside of the Cohesion pants. After 3 days, the 100% DEET solution (right in photo) was still quite wet, while the 30% DEET Solution (left in photo) had mostly dried. There was little evidence of any external damage to the pants leg.

 

Turning the pant leg inside out however, showed another result entirely. The 30% DEET solution had soaked through the outer shell layer and melted the middle Conduit DT layer and the inner liner. However, the damage was highly localized. [Does the photo below remind you of the Andromeda Strain?]

The damage under the 100% DEET application was much more significant, and large patches of the Conduit DT layer and the inner liner were melted away. As it turns out, this process is ongoing and the fabric continues to dissolve, unabated.

Mitigating DEET Clothing Damage

The evidence is quite clear and shows that DEET does dissolve breathable laminates. However, the strength of the DEET solution that the laminate comes in contact with is a determining factor in the amount of damage that will occur. Hikers who are concerned about the impact of DEET to clothing made using breathable laminates are advised to flush the point of contact with water to minimize potential damage.

Written 2009. Updated 2014. 

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12 comments

  1. Nice test bro!! I had heard this rumor a few years back but never had the stones to test it on my own gear. Thanks for the sacrifice and for sharing your results.

  2. I recently discolored my plastic Highgear watch with bug-spray (just partial overspray from my arm). I'd guess it's a polypropylene material, but it could also be HDPE (high-density polyethylene). Care to expand your experimentation?

    I'm just keeping bug-spray away from my gear or using a liquid that can be rubbed directly into the skin without overspray.

    Great topic.

  3. We salute those brave pants, which made the ultimate sacrifice in the name of scientific research! Good to know the rumor has some veracity.

  4. I've gotten a lot better at pointing my crampons since then. No rips for a while, now, with my newest pair of pants. :-)

  5. Chad – sorry for the delay in approving your comment. You got trapped in my spam filter. Let me see if I have an old watch somewhere to expand the DEET test. Good idea for a series of posts – maybe I should call for donations.

  6. Thanks for using your gear. I’d heard this rumor and can say it’s true of tent fabric. The only thing good about deet is it keeps my allergy to the out doors from showing up in red spots and welts as it does when ever I try to use one of the new safe products on the market. Sure wish they could come up with something as effective as deet and as benign as skin so soft Oh, and without the grammy smell.

  7. This comports with my own experience. Nylon is just fine (thank goodness for us climbers!) but other plastics are a crapshoot. It will melt plastic bags (making secondary containment a challenge) and is merciless toward swiss army knife handles.

  8. Today I had the misfortune of having a spray bottle of Ben’s Deep Woods with DEET get wedged sideways in the small outer pocket of my daypack. Somehow the plastic cover over the nozzle came off and the spray button was activated, releasing enough Ben’s to leak all over what I had in the bottom of the pocket. The main casualty was my Swiss army knife–I soaked the knife in warm soapy water in the sink to wash off the repellent, and when I rinsed it off I noticed fatal cracks and milky discoloration in the plastic, and in fact some of the plastic turned soft–soft enough to shave off with my fingernail! Very creepy. I’m slightly comforted in finding a few other entries online from other folks who’ve had this same thing happen to them–but still grieving for my knife which will never be the same. My husband says it’s “patina,” and the knife (multitool) still works… I wish there were a way to replace the damaged casing. But the bigger question is, do I want to buy another bottle of this stuff and use it anywhere near my body? I don’t think so!

  9. A fellow hiker in the Adirondacks once gave me a spare bottle with the comment “Its so good, it will melt plastic” (and gave me a big thumbs up while saying this).

  10. The chemical DEET is a plasticizer and will harm a wide range of outdoor gear containing plastics or film if not carefully stored and applied. Many repellent brands use DEET including OFF, Repel, Cutter and Ben’s to name a few. If you do use a DEET based repellent, as many do, use precautions when storing and applying to your skin. If you are concerned with the plasticizing effects of DEET use a repellent with the active ingredient, Picaridin. This active ingredient will not harm your outdoor gear or clothing and will provide up to 8 hours of mosquito and tick protection. I recommend a Picaridin 20% active such as Natrapel. The company I work for, Tender Corporation, manufactures both Ben’s and Natrapel.

    Frank Meyer, Chief Marketing Officer, Tender Corporation

  11. Good info. Wonder if DEET affects DWR finishes as well.

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