Permethrin on water resistant pants?

for what it’s worth, insect shield refuses to even try doing their thing to these kinds of fabrics.

Thanks Ben. I saw that too. Sawyer says their product can be used on tents, backpacks, etc. which almost all have some water repellent treatment. Curious others experience treating such fabrics.

“It depends.”

Wrangler doesn’t specify the water repellent coating, but I doubt it would stop Sawyer permethrin from bonding to the fabric. And since they don’t specify, it’s hard to know if you can wash it out – whether you want to or not!

I’ve sprayed Sawyer permethrin on shoes, socks, shorts, windpants, shirts, windshirts, hats, and a silnylon tent. It seems to work.

And even if permethrin doesn’t stick well to your new pants, treating your shoes and socks seems to be far more effective than other clothing:

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

— Rex

There are many different types of fabrics and coatings out there. For the pants you mention (wrangler cargo pants) they happen to be made primarily of nylon. Nylon is fairly water resistant, but it does soak some water. Depends on how the fabric/threads are handled. Generally speaking, it WILL pick up and hold permethrin in effective amounts for about 50 washings.

Anything than will absorb a little water will pick up and hold permethrin as a general rule. Wool, cotton, nylon, linen, etc…basically anything that will stain will also pick up permethrin. Polypropylene, in general, does not. However it has a molecular affinity for permethrin, so it WILL wash out after about 5-7 washings.

Coatings may or may not be a barrier to permethrin. Silicone coatings are not a barrier, generally speaking. A tent made of silnylon usually has a coating that will pass a certain amount of water molecules, hence permethrin will “stick” to it in rather effective amounts. But, the silicone can degrade or be washed out over a certain number of weather events, along with the silicone coating. Also, UV will destroy the permethrin molecule. Some coatings do not like permethrin, though. More like a polypropylene in nature. Poly in general has to have an infused dye rather than a surface dye. It is likely responsible for picking up more permethrin than would otherwise be accounted for by the raw poly.

Anyway, Cotton will accept permethrin for up to 70 or more washings, easily. Poly will be coated with permethrin for about 3-7 washings. There is no difference in the permethrin molecules between the various companies. Only the “carrier” or “solvent” is changed. Cheap horse dips often use petroleum products (it smells like kerosene) in high concentrations(10-25%.) Water based stuff usually tops out at around 7-10%. An effective coating can be used with a 0.5% solution. Lower if you let clothing soak for longer and will have excess. ALL excess should be exposed to UV before disposing of it. Permethrin will pass through a  water treatment plant and tiny amounts raise hell with the aquatic life. DO NOT DUMP IT DOWN A DRAIN or SEWER! DO NOT SOAK/APPLY PERMETHRIN IN YOUR WASHER OR SINK!  DO NOT DUMP IT ON THE GROUND WHERE IT CANNOT BE BROKEN DOWN BY UV! Of course follow all other restrictions about handling it. (I generally spray it on house foundations, floor joist in contact with the foundation, driveways on a sunny day, etc.) Avoid contact with house cats.

Thanks for the info James. I notice Sawyer and other liquid treatments say good for 6 weeks and or 6 washings. Would keeping the garments in a sealed bag in between washings extend the 6 weeks in your opinion?

brad, i asked sawyer the same question a few years ago and they said that it would likely help a bit.

Thanks Ben.

And even if permethrin doesn’t stick well to your new pants, treating your shoes and socks seems to be far more effective than other clothing:

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

I don’t buy it.  If that’s the study I’ve seen, they placed ticks in several places on persons’ bodies and watched what happened.  Shoes/socks were the only place where the ticks were put directly on treated materials.  For all other placements, they placed the ticks on skin somewhere.  It’s no wonder they killed more ticks on the shoes.

Also, “73.6 times less likely” is both bad English and bad math.

Not that any of that has bearing on Permethrin’s effectiveness on DWR’d clothing.

With two clicks, you could have found this:

If scientific journal articles were rejected for bad English or unusual math – we’d see about 90% fewer papers!

Three clicks for the other study:

Pathogen-free nymphal Ixodes scapularis Say were placed on the left shoe, right leg, and left arm of 15 (5/treatment group/d) human volunteers wearing untreated outfits or outfits treated with permethrin either commercially or using a do-at-home treatment kit.

I still treat virtually every piece of clothing I wear, and my tent too.

YMMV / HYOH.

— Rex

I agree with Rex. Personally, I treat everything except socks and underwear.  I have never had a reaction to it, but I am cautious about any poisons.
Using a 5 gallon bucket:
Mix about 4 gallons of water and various amounts of whatever stuff you can get.
For 0.25% ant dust, about 2.5lb in 4 gal is good enough.
For a 10% aqueaous solution, I mix about 250ml or half pint to 4 gallons.
(NOTE: This results in a low concentration solution. Since permethrin is attracted to clothing, this is fine.)
Shoes are first dipped in. Let stand about a minute and remove these, hanging them up to dry.
Rain Jacket is next. Again, about a minute, then hang up to dry.
Then my hiking cloths: shirt, pants. I leave these in for about a minute hanging them to dry.
Then sleeping cloths.
Then the tarp, backpack, sleeping bag or quilt, hat, bandana, drybags, etc. 
If there is anything left, I pour it into a spray bottle and spray around the house as needed: foundation, sills, around the cellar, etc. IFF there is any left, the walkway and decks are sprayed. Anyway, I make use of all the solution. NO LEFTOVERS. I don’t think I have ever had enough to use it for everything it could be used on.

I don’t do most clothing again…just new (after initial laundering) cloths. Any poly based fabrics (fleece, shirts, poly long johns, etc) is done yearly as the exception, since, these are known not to pick up as much permethrin. Other materials are usually done once, or done last…more to use any solution up than because the clothing really needs it. Sometimes, I will do my pants, or a set of wool long johns for example.

I assume it will last about 50 washings on nylon/cotton/wool. If that was the ONLY cloths I wore, 50 washings is around a year at once per week. Lifetime of my shirts and pants is around 6-9 years. Since I ONLY wear hiking cloths for hiking around 60 nights per year (and I have a few sets) I expect not to be bothered with doing nylon, wool, cotton goods again before they are worn out. I’ve been using permethrin for over 20 years.

Most of my hiking is in the ADK’s, Catskills, or Vermont. Really, ticks are a minor problem, though serious in nature. Black flies/mosquitoes are the main reason I use permethrin. It isn’t a repellant, though. You still need DEET.

Rex:  Yes, that first one is the study I’ve read.  (I read the whole thing.)  I’m not sure whether you were just showing me the study or disputing my interpretation of it.  The study itself actually mentioned the inconsistency of whether the ticks were placed directly on the treated clothing or on skin somewhere near the clothing, but neither that fact nor its potential implications was carried into the abstract/summary.  To me, that inconsistency makes any conclusions about shoe treatments being more effective than pants treatments (for example) questionable.  And, of course, ticks in the real world don’t get “placed,” so the study itself says nothing at all about the prevalence of ticks falling on shoes compared to legs.

My point is, it’s probably important to keep treating pants and shirt regardless of the study’s appearance of giving treated shoes most of the credit.  I personally treat pants, shirts, socks and/or scree gaiters, and a thin pair of glove liners to wear in camp.

James, from everything I read, DIY treatment only lasts 6 washings or 6 weeks. Insect Shield method will last up to 70 washings according to them.

Brad, no. Permethrin is permethrin. Only the solvents, temperatures and pressures vary. I think they might have been comparing Sawyers spray-on stuff.

James-I agree the chemical is the same, I don’t see the at home spray on application lasting 50 washings or the amount of time you mentioned.

Yeah, the volume of permethrin in a solution counts more than the percentage during a spray-on application. The methode of application is wrong. Your target really needs to remain wet for the maximum time allowed for good penetration. Like dying nylon fishing line, the longer you leave it, the darker it gets…up to a point.

Usually just till the surface is damp, is not enough. Soaking, however, will allow all portions of a fabric to absorb the chemical: outside hairs, thread body, and all internal twists & weaves. .5% is good, but, I have trouble with soaking a single pair of hiking pants with what comes in a Sawyers bottle. I believe Sawyers comes in .37l bottles.

Hmmm .37L is 12oz, At that dilution (0.5%,) you would need 10.75 bottles of Sawyers to make up one gallon of a dip, should you be inclined. Or 43 bottles for 4 gallons.

As the fabric attaches to permethrin or visa-versa, it leaves solution. Even when it is down to a .1% solution, it will still work, just leave in in a bit longer, exactly like a dye bath. Or, diluting a .5% solution in half by adding an extra 12oz of water will let you soak both your pants and shirt for a half hour and do a longer lasting job than spraying it on.