Permethrin long term technique

[Arthur]

Soaking with Permethrin is supposed to last 6 weeks or so and multiple washings. Commercial applications are supposed to last 70 washings.  How do they do it?  It seems to be some secret handshake process.  Sure would be nice to know how us mortals could accomplish the same thing. Any ideas?

[Brad Rogers]

I think the “home” applications are 30% permethrin and the insect shield treatment is a much more potent solution that can’t be sold to non commercial buyers.

[Ryan Smith]

I always assumed they put it under high pressure and/or heat which made it bond to the fibers better. No real idea though.

[BlackHatGuy]

It certainly has high heat as part of the process. I send my clothes to Insect Shield for their professional treatment, and one of the cautions they give is that they use high heat, so anything shrinkable will, certainly, shrink.

[Matthew / BPL]

^Yep. My shirt came back from Insectshield smaller. Pants and hat came back fine.

[Rex Sanders]

https://backpackinglight.com/forums/topic/91472/

No statistically significant differences in number of tick bites were detected between commercial permethrin treatment (19.33%) and the do-at-home permethrin application method (24.67%)

— Rex

[Bob Moulder]

This past spring I wore the RailRiders Eco Mesh pants with InsectShield on my local hike where the woods were chock full of ticks.

I really don’t like these pants because they are so huge in the legs, but I wore them just to see the effect of the permethrin treatment when a tick latched on.

Answer: NOTHING!

I actually didn’t find a tick on my leg but quickly found one crawling up my dog’s front leg. I took that tick, put in on the thigh area of my “InsectShield” pants, sat down on a rock and observed it for a while.

I did not see any unusual behavior at all as the tick crawled around… no signs of distress whatsoever. I had to corral the tick occasionally to keep it in the same area as I watched it for 15 minutes. Still nothing.

This was only the second time I wore these pants and they have never been washed.

Here’s a photo of the actual tick in question on the actual pants in question. Definitely a deer tick.

[Matthew / BPL]

I’m hoping the treatment is effective in repelling mosquitos. My fingers are crossed!

[James Marco]

Permethrin is a nerve agent. It can take several hours to work on clothing, but, once an insect has landed and gotten it’s feet on the fabric, it is doomed. It is NOT a repellent like DEET. It will ward off any insects because they have a minimal sense of self preservation, though. Once they plant their feet, they shortly (like 10 seconds or less) loose all interest in eating/biting/stinging. As an example, you will see a mosquito land on your shirt, then try to slide his proboscis between fibers in the fabric…he may do this repeatedly on nylon or other close knit fabric. Then he will use his front feet to wipe his proboscis clean. He will die eventually, but he may bite in the first few seconds. But, it will not be a bad bite, nor, will she drink her fill. Sooo, yes it is sort of a repellent, But a few sprays of DEET are more effective used this way.

There is no difference in how effective a home dip and the commercial method are. Permethrin acts as a dye on the fabric. Heat, some chemicals can speed the bonding, but it will be the same after it dries and is rinsed. Loose molecules should be rinsed off…they can bleed onto your skin, or, into the environment. I dip my cloths, dry them outside, then rinse them all in a 5gal bucket. All excess water is used on the foundation/driveway, but you can also pour any excess on the road and let UV break it down in sunlight. Then, I launder my cloths, normally. Anyway, the concentration of permethrin left on a fabric depends on the fabric. Dyed nylon will not hold as much as clear nylon. Wool will not hold as much as dyed wool, nor as much as cotton. PET absorbs very little. Vinyl absorbs enough to be effective. So, it is difficult to say. Sometimes, dyes are added directly to the PET while they are making threads, so this might be the ultimate in longevity. I usually use 2.5% permethrin mixed to a 1% dilution. Dip, dry, rinse, launder, and dry. This takes about 4-6 hours depending on humidity, etc.

Depending on the fabric, I get between 20-70 washings out of my hiking cloths before a retreatment is needed. My fleece looses effectiveness in about 3-4 launderings or rain showers. My long-johns I have never had to retreat…about 30 or so launderings before they start thinning beyond usability(wool.) Sawyer spray has a rather low concentration. I apply it heavily to one pair of pants and one shirt and let it dry. But, at .5% it doesn’t really have enough molecules of permethrin to come loose…ie, there is no excess. After several sprayings, you should rinse/wash them before wearing them.

About 1% of the population is allergic to permethrin. Soo, test it to be safe. It is specific to insects, fish, amphibians and of all things, cats. DO NOT let wet spray get onto a cat. You can often buy it as a flea spray for dogs. I think it was derived from the chrysanthemum plant.

[JCH]

So…I live in NC Florida, otherwise known as the tick capital of the world.  I have looked down to see a WAVE of seed ticks crawling up my leg like I had stepped in an anthill…easily more than 40.  We. Got. Ticks.  Oh yeah, and mosquitoes too…bigguns!

I have not had a tick latch onto me in the 4 years I’ve been wearing IS treated clothing…knock on wood. I’ve found them ON my clothes, but not a single bite.  Mosquitoes have not biten me through IS treated clothes.  In fact, the shirt and hat actuallly do a good job of keeping them from landing on my face and neck. Sure, they buzz around being a pain, but do not land.

Obviously this is annecdotal at best, but I will never again go out without IS treated socks, pants, shirt, buff and hat. And I will tell this story to anyone who will listen.  HYOH.

 

[Bob Shuff]

Hi James,

Your detailed post is very authoritative, and I want to believe it all.  I also have Rail-Rider shirt and pants and a (Sea to Summit?) treated head net.  I’ve thought about sending in some other clothes, or treating them myself.

Regarding your statement about how long the home or professional treatment lasts, how do you know this? It seems unlikely you would have sufficient personal “sting” experience to know how many washing until it starts to lose effectiveness.

Like I mentioned, I want to believe, but previously I heard the professional treatment lasted longer, and assumed, maybe wrongfully, that the company could back up those claims.

[James Marco]

Bob, I have been using permethrin on my cloths about 15-20 years. I have tried all sorts of dip methodes and that is the one that works without getting into the environment. As far as bites and stings, yes. I have used permethrin long enough to to know when they start loosing effectiveness. You can watch a mosquito land and pretty much judge how effective it is by how long it takes him to loose interest in biting. Not all mosquito’s do this BTW. Right after they hatch in spring, even DEET doesn’t deter them…they are really voracious.

Way back when, I would use Ant Killer on my clothing. Then I found out that it was deadly to fish/amphibians and cats and would NOT be broken down in a sewage treatment plant. Soo, I sort’a developed my own technique for using it. A LOT of people have picked it up, I am sure.

Commercial processes just do it in large batches, and reuse the solution. Heating does help with bonding (again, like dye,) but if you start with a 1-2% solution and let it dry on your cloths, that’s enough to work fine. But, it takes a while. The first couple years I had mixed results…not enough at around .25%. Jerry at Backpack Gear Test (web site I used to visit a lot) told me to use more. So I upped it to around 1% and it works fine. He used it since 1967-69 in Viet Nam. (Military issued a LOT of it.) I studied up for several years on it. No problems found with people except some allergies.

This was maybe 15 years before sawyers came out and likely 10 years before Rail Riders. Basically, I dip all hiking cloths once. At around 50-70 washings, the things are worn out anyway.

[BlackHatGuy]

@jamesdmarco: Do you know how much sweat affects its longevity? Say I get 50-70 washings after treatment. When I hike, I sweat. A lot. Especially in warm weather. My shirt and pants can be pretty soaked after a long day hiking. Does this lower the 50-70 to a different number, or is it just the detergent that affects it, not sweat itself?

[James Marco]

Well, water will effect dyes. How much? Good question. I believe there is too many variables to say definitively. But, I think (once in a while) that you might loose about the same as a laundering after a week of sweating. Surficants (detergents), bleach, high oxygen levels, all tend to break the hydrogen bonds used for permethrin. But again, this is very minor. Sort’a like a dyed cotton shirt. The more you wash it, the lighter the dye becomes. At least that is the way I think of it.

[Gerry B.]

I do know they subject the clothing to 150 deg F heat for 30 minutes because I asked a few months ago when regarding the treatability of a silk liner (no)!

 

[JCH]

Heat is definitely part of the process, but I doubt thats it.  The process is patented so pretty much all we can do it guess what is involved/how it works.  I have sent previously treated clothes back for re-retreatment…but I’m not certain if it was abosolutely required or not.  I hadn’t laundered them 70 times, but after 2 years, I figured it prudent given the number of ticks and mosquitoes we have.

[Bob Moulder]

Given these responses it appears my notion of how it is supposed to work is obviously incomplete.

But I figured that after 15 minutes with a tick crawling around on the permethrin-treated fabric that I should see some noticeable reaction.

A couple of months ago I treated some other clothes using a home mix made with Martin’s permethrin diluted to 0.5%. I let them dry thoroughly and put them in one of those big air vac bags. I’ll give those a test when cooler weather arrives… maybe just let some skeeters land on my arm and wait for them to chow down. I’ve definitely had them bite me right through thin polyester clothing.

[Bob Moulder]

Heat is definitely part of the process, but I doubt thats it.  The process is patented so pretty much all we can do it guess what is involved/how it works.

I have also wondered if perhaps using a stronger solution and drying the treated clothes on very high heat could replicate the process… but I’ll bet they use some sort of [substance+process] that emulsifies the permethrin.

[JCH]

…but I’ll bet they use some sort of [substance+process] that emulsifies the permethrin.

+1

When I first became aware of Insect Shield many years ago (the first commercially available example I am aware of was from Ex Officio and branded Buzz Off) there seemed to be a bit more “honest and open” discussion of what the process actually was.  I’ve spent time on the Insect Shield website over subsequent years and most of that information has been removed, replaced by marketing platitudes…Surprise!  In the beginning when IS spoke of a very tight bond between permethrin and the fabric I think they used the word “molecular” and hinted that the treatment and the fibers became “fused”  into a singular thing.  Diminishment of protection was not a result of the permethrin being washed out (although, like dye, I would not be surprised that it is…very slowly), but more that sun and oxygen were doing what they do best and simply wearing it out.

I think the process is much more involved that heating up the solution/garment.

[Bob Shuff]

If it’s patented, then the information should be publicly available – not that I would know or have interest in digging into it.  Maybe someone else with more time or experience could?

I wouldn’t be surprised if the IS website became more legalized than marketing platitudes.  Molecular was probably over-reaching and was removed when they realized that.  I’ve seen a lot of company’s closely guard their trade secret, only to find out later that it’s clever, but not ground-breaking innovative.  Of course, someone from IS could set us straight if their process is patented.  I give them credit for having as much info on their website as they have.  I may also send them some garments to treat soon.  It’s worth it to me vs DIY, and then I’ll be more confident that I didn’t screw it up.  The bundle they have seems like a good deal for me an my son’s clothes – just need to decide what to send in.

The shrinkage warning worries me about my Smartwool/Icebreaker clothes.  I usually wear these for sleeping so maybe that’s not as critical.

Socks seem like an obvious one – any experience to report on that?  A windshirt/jacket and buff would also seem like no brainers.  Gaiters? Maybe my Tilley hat? (I’ve heard that one shrinks so I never put it in the dryer and stretch it wet).  What else would you guys treat?

[BlackHatGuy]

I did treat my Darn Tough wool socks, they came back smaller and, interestingly I guess, not as soft and pliable, if that makes sense. I still wear them on pretty much every hike though.

[JCH]

Bob, as mentioned, I treated socks, pants, shirts, buff, and hat and that is what I recommend.  Overkill? Perhaps, but as you said, its worth it (for peace of mind). Were I on a budget, I’d treat socks and buff (most obvious entry points).

Shrinkage is modest, but real, and if the item was slightly baggy prior to treatment likely it will fit perfectly after.  If it fits perfectly prior, it will be tight after :)

[James Marco]

I used to do a lot of dying of various materials, from feathers, rubber, vinyl, poly cord, nylon lines, etc. I did this as part of my fly tying. In most cases, the dye/substrate bond is a loose hydrogen bond. In most cases the primary solvent is water. Some acid may be used like vinegar, or in exxtreme cases like polyesters maybe a slightly stronger acid like dilute sulfuric acid (used to buy it at a garage as battery acid.) Heat WILL improve the set, but cold dying is possible for silk, wool, and other “shrinkable” materials. It just takes about 10-20 times longer. Unlike colored dyes, permethrin is fairly clear so it is nearly impossible to judge by sight. But a commercial processor no doubt uses a spectrum analysis from a known light source to read how much is on the fabric.

In most cases, though, you can just let it sit in a bath of .25% solution overnight and it will bond as many molecules of permethrin as it is capable of bonding. The solute (the dissolved permethrin) will gradually be reduced until it reaches a balance between the concentration of the bath and the cloths, or, equilibrium. IFF you add more permethrin, it may bond more, or, it may do nothing.

Soo, this indicates that they would use a strong bath (perhaps not water,) under pressure, and heated. Removed from the bath, they would then have to wash out the excess molecules from any cloth. Again, there are environmental concerns, soo, they likely reuse this and chemically filter it (or UV it strongly) before release. I am sure they have a lot of fancy equipment to do this with.

But, you can do this at home with very simple equipment and even if it is not heated or done with special solvents, most clothing can be treated. Nylon, wool are the two I do most often. You just have to have a 5 gal bucket, perhaps a gallon of 2% permethrin and a gallon (warm if desired) of water. The permethrin will stick. And, it will last. Fleece is a problem, it doesn’t stick too well, nor as strongly. But if I needed a fleece sweater for hiking, it was undoubtedly too cold for mosquitoes. An Ultra-Light wool hiking shirt is usually enough down to about 40F. Long Sleeves are highly recommended. Long Pants are highly recommended. No, I do not do my socks, nor underpants. On a day in the NE with literally a thousand black flies buzzing around my head, I get maybe 2-4 bites on a two week hiking trip. In a few cases, I have bumped into clods of voracious mosquitoes, but mostly, they do not bite. Last week I came home with one mosquito bite after a week long hiking trip thru two beaver swamps and many lakes. Works for me.

[Rex Sanders]

For best results against ticks, treat socks and shoes:

The success of permethrin-treated clothing in reducing tick bites varied depending on the specific article of clothing. Subjects wearing permethrin-treated sneakers and socks were 73.6 times less likely to have a tick bite than subjects wearing untreated footware. Subjects wearing permethrin-treated shorts and T-shirts were 4.74 and 2.17 times, respectively, less likely to receive a tick bite in areas related to those specific garments than subjects wearing untreated shorts and T-shirts.

https://backpackinglight.com/forums/topic/91472/

— Rex

[James Marco]

Rex, Yeah. I hate to have any allergies develop, though…especially on my feet. But, I wear heavy wool hiking socks OVER my hiking pants which are treated. And, I do not wear T shirts. Typically a UltraLight long john top(long sleeved) or nylon long sleeved top is actually cooler than exposed skin in sunlight and saves a LOT in scrapes and cuts. These are also treated. Only had one common tick on me in the past 15 years using permethrin. He was quivering and looked to be very sick…course, maybe I was quivering…hey, ha.

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