DEET and dyneema

Are you sure your pack is made out of dyneema? I presume your pack is nylon with dyneema ripstop. I've seen light weight nylon (30D) severely affected by high concentration DEET before. I'm sure concentrated liquid DEET could do some damage to heavier nylons if it sat there long enough.

Yes is the pack fabric with Dyneema grid pattern, so assuming it's nylon (must find who switched my coffee to decaf this am). I've seen some posts where nylon is supposedly not affected but the DEET may have just eaten away at the coating (compared to the other non-affected pocket)

This convention of calling fabrics that are 95% nylon "Dyneema" complicates every discussion about fabrics of this type. The Dyneema component of the fabric is essentially impossible to damage with any chemical. It's polyethylene, which is the same material as the bottle the DEET is stored in. No chemical available to consumers will affect Dyneema.

Nylon is not as inert as Dyneema, but it isn't significantly harmed by DEET. I remember reading that, under some conditions, prolonged exposure to DEET at high concentrations can cause Nylon 6 to become more elastic, but this isn't likely to happen under normal use conditions, and strength wasn't affected.

Urethanes (like spandex, Aquaseal, Platypus Plus bottles, and many fabric coatings) are destroyed by DEET.

I used to use Jungle Juice (99.8% DEET) for its compactness and light weight. It did no harm whatsoever to my nylon clothing, nylon / silnylon backpack, tents, or shoes. But the oily stuff did take away some of the button markings on my camera (hmmm what does this button do again?) and it also mucked up my glasses.

Colin, I'm unsure what Dyneema is exactly, however, if it's indeed a polyethylene (similar to HDPE/LDPE), there are numerous compounds that will act as a solvent on it, including most aromatic / halogenated hydrocarbons, as well as aromatic ketones.

Cameron, I have to disagree with you. Dyneema and Spectra are Ultra High Molecular Weight Polyethylenes. UHMWPE, like HDPE and LDPE, are among the most chemically inert polymers in common use. Only the fluoropolymers have a better overall chemical resistance profile among common plastics. They are certainly not soluble in many aromatic or halogenated hydrocarbons, or in many aromatic ketones. I have stored toluene and xylenes in PE bottles for a year or more in the lab with no perceptible effect on the container, and in bottles with PE lids for much longer. Various sources list the resistance of UHMWPE to dichloromethane as "excellent" or "unaffected". The aromatic ketone avobenzone is a component of sunscreens, which are always sold and stored in PE bottles. Also, UHMWPE is by far the most inert polymer among the polyethylenes, and chemicals that will gradually affect LDPE won't necessarily affect UHMWPE.

At elevated temperatures, over long periods of time, acetophenone, decalin, and other members of the chemical families you mentioned can begin to affect the properties of polyethylenes. These chemicals are used in primers that enhance adhesive bonding between polyolefin surfaces. But those data are hardly relevant to short-term exposure of UHMWPE to DEET. No common cordage or textile fiber material is more inert than UHMWPE, and I stand by my assertion that no chemical in the form of a consumer product will affect it.

Colin, I'm more on the life sciences than chemistry side of things, so most of my knowledge comes from analytical point of view.

I do agree that it is unlikely any compound found in DEET, or at a concentration available to most consumers, is likely to effect HDPE. My comment was more meant to caution that there are such compounds available, and that given the thickness of storage plastic vs fabric, as well as elevated temperatures as a result of UV / heat source exposure, it is possible to have resulting damage.

I can offer some experimental results. 100% DEET dissolved HDPE, surface sticky after 24 hours. A large drop of 100% DEET left on a piece of Cuben Fiber (just Cuben Fiber, not the stuff that's bonded to nylon) and left to evaporate at room temperature did not appear to have any effect.

I was trying to figure out if there's any safe way to repackage DEET. I called 3M (manufacturers of Ultrathon). They told me that they coat the inside of their tubes with "something", but wouldn't tell me what, and told me never to repackage because it attacks virtually every kind of plastic, but refused to elaborate further.

For what its worth, I have my deet stored in an hdpe dropper bottle and hasn't been an issue. Its been in there for atleast six months.

In the interests of science, I sprayed both water bottle pockets with water from a spritzer and the side soaked in DEET lost a little beading ability and seemed to soak up a little more. Lucky this was the outside of a water bottle pocket it seems. Also the soaked pocket has almost lost its "gummy"-ness…. almost.

Deet will not adversely affect the nylon they use in climbing ropes and slings

This has been tested and the nylon stays close to full strength

As to dyneema, ill have to look up the references when im home, but i dont believe it affects the dyneema they use in climbing applications either

;)

"They told me that they coat the inside of their tubes with "something", but wouldn't tell me what, and told me never to repackage because it attacks virtually every kind of plastic, but refused to elaborate further."

I am not sure I believe the "attack" part. After cutting apart several Ben's 100% DEET bottles, I could find no evidence of any coating.

DEET is basically an oil. Generally, if WG will attack a piece of plastic, so will DEET. Generally this will "saturate" into most plastics. If this is what they mean by "attack" they should have said so. It is NOT usually destructive. Some plastics soften easily in the presence of oils. Some silicone/plastic blends used for coatings (on the Steripen Journey for example) literally turns into a gummy mess. Some plastics do not. PET, nylon for example soak very little. PET is often used for FUEL containers! HDPE is not effected by DEET…well maybe slightly, but not enough to notice. These are used as slides in guns where oil is often heavily applied. Hard plastics often fare worse. They loose integrity but will reharden as the oil disipates. Oil resistance was one of the properties needed to make sliding parts for items, sewing machines for example.

Note: I usually carry two bottles of DEET. I dilute both with WG. So, it is probabobly only 80% when I use it. Polyethelene or PET will not be disolved by this mix. Nor will my pants, usually nylon. Nor my tarp (silnylon.) Nor, does it effect the silicon coating. You thin silicone calk with WG to apply it. I am not sure about the coatings on the Gossamer Gear packs, but I had a bottle leak in a pocket a few years ago. It still works. Never really tested for waterproofness, though. I use a liner/compression bag so it wouldn't bother me if it did. Spectra line is not effected by DEET (well, maybe by lubricating the fibers a bit.)

Let me preface by saying I have no background in chemistry but I speak from some experience. DEET will partially dissolve the polyurethane coating on the Dyneema gridstop fabric but will not do any noticeable harm to the fabric itself.

86 the Deet! Back in the day when I worked for the USFS we routinely used DEET as a paint remover. Who in their right mind would want to put paint remover on their skin? Now-a-days I use Picaridin based bug juice and find it pretty darn effective; there are a variety of brands available, and even Avon has a line called Bug Guard Plus. I don't in the least miss the sticky, oily residue on my skin, or mucking up the surface or printing of something that I briefly touched. Happy Trails!.

Monty, nobody said that you should apply the DEET to your skin.

It seems like we keep going over this same point again and again.

You apply the DEET to some portion of your clothing where your body heat will slowly vaporize the DEET. The best place for this, in my opinion, is on the outside of your shirt collar. The heat from your neck will vaporize it, and the vapors rise around your head, thereby minimizing mosquito flights.

I carry a tiny container of DEET that is smaller than my little finger, and that works fine.

–B.G.–

"Monty, nobody said that you should apply the DEET to your skin."

Really? Tell that to REI:

"Protects exposed skin areas against mosquitoes, chiggers, fleas, gnats and ticks"

In this day in age, I believe there are many other repellent options which may not be as convenient and effective as DEET, but are potentially much safer. Here in Maryland, we have to constantly deal with tons of deer ticks and those nasty all-day Asian Tiger Mosquitoes, yet my kids have managed very well with DEET free products their entire life. They don't know what it feels like to burn their eyes out of their sockets after accidentally wiping their face with a DEET coated wrist, or witness their rain jacket de-laminate and melt away.

Matt, you seem to be reading the REI words, but you put your own spin on what they mean.

"Protects exposed skin areas against mosquitoes, chiggers, fleas, gnats and ticks"

Where in those words does it state that you apply the DEET to the skin?

Answer: it doesn't

It says that if you apply the DEET (in some undefined fashion) that your exposed skin will be protected.

I make a rule of never getting the DEET on my hands and never getting it directly on skin. I will get it on clothing that is an inch away from my skin.

–B.G.–

Me? I don't spin anything!

Seriously though, just how is the "layperson" gong to interpret that marketing bullet?

Fwiw, I worked at REI for many years, and I am highly certain that 90 percent of the people who bought Jungle Juice wouldn't have thought twice about opening it up, squirting a few drops of it in their hand, and rubbing it directly onto areas where they didn't want to get bit by bugs.

By the time they put the cap back on, the instructions on the back of the bottle were gone forever, eviscerated away by their deet-soaked hands.

:)

From the EPA:

DEET is designed for direct application to people’s skin to repel insects.

http://www2.epa.gov/insect-repellents/deet

From the FDA:

When applying insect repellents to children, avoid their hands, around the eyes, and cut or irritated skin. Do not allow children to handle insect repellents. When using on children, apply to your own hands and then put it on the child. After returning indoors, wash your child’s treated skin or bathe the child.

http://www.fda.gov/Drugs/EmergencyPreparedness/ucm085277.htm

DEET is most certianly intended to be applied to skin.

Yes, it is acceptable to apply DEET directly to the skin. No, it is not required for it to be applied directly to the skin.

DEET makes problems if you get it on your fingers, then spread that into your eyes or other sensitive spots. It isn't lethal, but it is just a problem. When I was in the military many years ago, we used Jungle Juice (DEET), so I had to learn the hard way what problems are caused on skin.

DEET works effectively if you put it on clothing as I suggested. If you apply it to the wrong parts of clothing, then it isn't going to do anything, but if you apply it to the right parts, it works. Obviously, there are fewer toxicity concerns if you apply it to clothing instead of to skin.

DEET lasts longer if you apply it to clothing as I suggested. If you put it on your fingers to apply, you will probably wash most of it off later. Instead, if you put it on clothing, you probably won't be washing it off during the course of your backpacking trip. Therefore, small amounts of it will still be there, still vaporizing, and still providing a protective vapor cloud. The companies that sell the stuff would probably prefer to see you using a lot of it, so they talk about applying it to the skin.

If you guys really want to put it directly on your skin, then that is OK by me. I just would not recommend it.

–B.G.–

Hi Bob. I agree that some strategically placed DEET on one's shirt may be effective; however, depending on the fabric, it may just dissolve! Or weaken substantially. I prefer to wear a long-sleeved, tightly woven fabric shirt such as the BPL Thoroughfare that was once sold on this site…'skeeters can't bight through it. Then I apply Picaridin – preferably the one made by Sawyer – to wrists, face and top of ears. Then I,m good to go.

As for the manufacturer's preferred method of application of DEET, allow me to quote from Ben's 100 Max Formula (96%): "Apply a few drops on your hands and wipe on exposed skin. Rub in well and clean hands after applying. Keep off of synthetics, plastics, furniture and paints. May damage leather. Hazard to humans and domestic animals. Do not apply over cuts, wounds or irritated skin. Do not apply to eyes and mouth or the hands of young children. Use just enough to cover exposed skin and/or clothing, not under clothing."

Also, from Repel Sportsmen Max (40%): "…Slightly moisten skin. Use just enough repellant to cover exposed skin and/or clothing."

I could also quote from REI's brand, but the directions have mostly been dissolved away. Oh well.

Anyway, I'm averse to putting something as caustic as DEET on my body now that there are alternatives available; at one time it was the only game in town, but I learned to manage the 'skeeters with long pants, long-sleeved shirt and a head net, a sometimes hot and uncomfortable solution, but I happen to like my liver. Happy Trails!