Permethrin Soak Method Guide

Permethrin Soak Method Guide

Permethrin is an insect repellant and insecticide that bonds to fabric and can be used on your clothes, tent, or hammock to prevent Lyme Disease, Rocky Mountain Spotted fever, or the Zika Virus by killing ticks, mosquitos, and insects that land on your stuff. The liquid Permethrin application techniques discussed below are only for treating clothing or outdoor gear and are not intended for human or animal use.

Soak or Spray: Two Ways to Apply Permethrin to Clothing and Gear

There are two ways to self-apply Permethrin to clothing, tents, and hammocks: spraying or soaking. Spraying your clothes or gear is a convenient way to treat them with Permethrin if you have a limited number of items. To learn more about the spray method using pre-mixed Sawyer Permethrin, see Treating Your Clothes with Permethrin. Soaking your clothes in Permethrin is the second way to treat clothing or outdoor gear and can be useful when you have bulky or a large number of items to treat. Before you begin, be sure to read all labels and documentation that comes with your Permethrin solution to determine if it is legal to use for this purpose in the United States. If in doubt, call the manufacturer and ask.

Permethrin treated clothing kills the ticks that land on it as long as you retreat your clothing periodically to maintain its effectiveness
Permethrin treated clothing kills the ticks that land on it as long as you retreat your clothing periodically to maintain its effectiveness.

How long does Permethrin Treated Gear and Clothing Remain Effective?

Both methods of Permethrin self-application, spraying, and soaking, remain effective for 6 weeks or 6 washes. You can prolong the effectiveness of self-applied Permethrin by storing permethrin-treated gear or clothes in black plastic bags (since sunlight breaks down Permethrin) or by hand washing items because the agitators in washing machines also accelerate its decay.

There’s anecdotal evidence that soaking your clothes with Permethrin instead of spraying is effective longer, but there isn’t any publicly available laboratory to support that conjecture. It’s just common sense that soaking will penetrate both the inside and outside of a garment while spraying it will just cover the outside.

If you want a longer-lasting treatment that will last up to 70 washings, you can send your clothing to a company called Insect Shield which has developed a proprietary process for Permethrin application that lasts longer than what you can do at home. I have no idea what they do that’s different, which is probably why they keep it a trade secret. Here’s a link to the Insect Shield order form that you use to send clothing you want them to process. The prices are listed on the form.

You can also buy Permethrin treated clothing off-the-shelf from many manufacturers.

Why would you soak clothes with Permethrin instead of spraying them?

Soaking can be more convenient if you have bulky items (like a tent or hammock) or you want to treat or many articles of clothing. Soaking is also likely to provide better coverage than spraying, including the inside and outside of garments than spraying which may miss spots. If an insect avoids the outside of a garment and makes it to your skin, there’s a good chance that it will still be killed if the inside of your clothing has also been pre-treated with Permethrin.

Martins Permethrin 10 percent
Martins Permethrin Concentrate

What is the most economical way of soaking gear and clothes with Permethrin?

While you can soak items in the pre-mixed 0.5% Permethrin Solution sold by Sawyer, it is more economical to buy a highly concentrated Permethrin solution like Martins 10% Permethrin and dilute it down to the recommended 0.5% strength solution recommended for treating fabrics. Concentrated permethrin solutions are also available in many feed and hardware stores.

While often intended for veterinary or agricultural use, highly concentrated Permethrin solutions diluted to a 0.5% Permethrin concentration are thought to be as effective at killing insects as the pre-mixed 0.5% Sawyer Permethrin solution. No one knows definitively in the absence of laboratory testing, although anecdotal accounts from many people suggest this to be the case. Follow all manufacturer product instructions and use them at your own risk.

How to dilute concentrated permethrin.

If you choose to dilute a concentrated form of permethrin like Martin’s 10% Permethrin, you need to reduce it to the 0.5% concentration recommended for clothing treatment. Many concentrated Permethrin solutions come with a built-in measuring cup for this process.

I prefer bagging up the clothing I plan to treat with Permethrin in 1 gallon freezer bags before pouring the Permethrin solution over them and letting them sit and soak.
I prefer bagging up the clothing I plan to treat with Permethrin in 1 gallon freezer bags before pouring the Permethrin solution over them and letting them sit and soak.

If you use a 10% Permethrin concentrate, you want to dilute it with 19 parts water and 1 part of 10% permethrin concentrate to produce a 0.5% Permethrin solution. For example, if you wanted to make a gallon (128 ounces) of a 0.5% Permethrin solution using water and a 10% Permethrin solution, you’d mix 6.4 ounces of 10% Permethrin solution with 121.6 ounces of water. If you do this using a 1-gallon plastic water bottle (shown above), you’d pour off 6.4 ounces of water and replace it with 6.4 ounces of the 10% Permethrin concentrate. Shake well to mix it up.

I recommend wearing protective gloves when working with Permethrin in any concentration, keeping it away from all animals, food, and water supplies, and only using it in a shady, well-ventilated, outdoor area. All of the containers used to hold Permethrin should also be properly labeled and disposed of as recommended on the product label by the manufacturer.

One reader has reported a sensitivity to diluted Permethrin that results in a burning sensation on their skin when their garments get wet after treatment. If in doubt, treat a test garment and wear it in rain to determine whether you suffer from this sensitivity. If this is the case, send your clothes out to Insect Shield for professional treatment or spray using Sawyer’s pre-mixed Permethrin.

Pour enough Permethrin solution to soak each item and then let sit for a few hours so that ot fully soaks the material.
Pour enough Permethrin solution to soak each item and then let sit for a few hours so that it fully soaks the material. Sawyer recommends 3 ounces of 0.5% Permethrin solution per garment. But you can add more if it’s needed to soak the item as long as it’s diluted to the same 0.5% concentration.

What’s the best way to soak your clothes with Permethrin?

While you can dip your clothes in a large bucket of 0.5% Permethrin (some people hold Permethrin Parties to do this with friends), I prefer bagging them individually in 1-gallon freezer bags and pouring a smaller quantity of Permethrin solution into each bag. This eliminates having a large amount of leftover Permethrin that is complicated to safely dispose or store.

I then massage the liquid into the garment and let it sit for a few hours to fully soak through all the layers of clothing, before pulling it out of the bag and hanging it up to dry in the shade. Sunlight breaks down Permethrin, so you should avoid drying Permethrin soaked clothing on a clothesline in the sun. Just let it air dry.

Once dry, the Permethrin treated clothing is ready to wear
Once dry, the Permethrin treated clothing is ready to wear.

Once the garments have dried, they’re ready to wear. There’s no need to wash them or dry them in a drier before use. Doing so will only begin to break down the Permethrin that has bonded to the garment’s fabric.

Can you soak clothing using pre-mixed 0.5% Sawyer Permethrin?

Absolutely. It can be far more convenient to soak your clothes using Sawyer Permethrin since it’s pre-mixed to the correct 0.5% concentration without having to dilute concentrated Permethrin, safely dispose of contaminated containers, or left-over Permethrin solution. It’s just more expensive.

How should you dispose of unused Permethrin solution?

If you have leftover Permethrin solution, please don’t pour it down the drain. Permethrin is deadly to fish and harmful to people if ingested in its liquid form. The safest way to dispose of it is to let it evaporate. You can also store any remainder in a bottle for future use.

Liability Disclaimer: The author of this article and website is not responsible for any damage, personal injuries or death as a result of the use of any information, maps, routes, advice, gear or techniques discussed herein. All activities are carried out at your own risk. 

Updated 2020.

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42 comments

  1. I have been doing this for years. Clothing, hats, socks, sleeping bag and am able to sleep outside in Alaska in the summer without a net. Just permethrin and DEET on exposed skin. I also treat my dogs bed, and the comforter on my wife’s and I bed, (the dog comes up there). On heavy tick days my wife just shakes the dead ticks off the comforter in the morning. No more ticks in bed. Great, and highly recommended.

    One thing missing from the article is the formula for dilution. It is:
    C1*V1 = C2*V2, where C1 is concentration of your concentrate, V1 is the volume of the Concentrate, C2 is the final Dilution and V2 is the volume of the final concentration. It works like this. I use concentrated permethin at 38% and want to end up with 1 liter of 0.5%. The formula is:

    0.38*V1=0.005*1000ml, goes to V1=(0.005*1000)/0.38 = 19.7ml.

    Use 13.2ml of 38% permthrin to 1 liter of water to achieve 0.5%.

    • Cliff – I’m having trouble following your calculations. Isn’t 5% = .05 (not .005)? That would mean you would use 132 ml of 38% permethrin to 1 L of water.

      Also – how did you get 19.7ml?

  2. How about Gordon’s Permethrin 10

  3. 1.75 ounces of your 36.8% solution per gallon of water will give you a 0.5% solution.

  4. Why is there such a huge difference in the concentration for treating a yard vs the unpublished usage outlined here? For example 1.5 fluid ounces to 10 gallons water to treat grass. Whereas this article indicates 6.4 fluid ounces to 1 gallon of water. That’s a huge difference. Am I missing something? Just want to make sure I’m being safe. Although I suppose since the product specifically says to not apply to clothes in any concentration….

    • Jeff, it must presumably be that the higher the concentration the faster / more reliably it works / longer it will last. If you put very concentrated permethrin next to your skin it would probably work better but would almost certainly not be tolerated.

  5. This the first time I’ve used permethrin and am spraying my cloths. I have to admit I have’t bee as careful as I should and twice now I am dizzy, nauseated and tired. Is this an effect of the Permethrin or just a coincidence? Getting ready to go to the BWCA and expecting lots of bugs.

    • Kind of hard to say. I have no idea what you’ve purchased or how you’re using it. Maybe you should just send your stuff to Insect Shield.

    • Mima – I had tried the aerosol spray and found it very difficult to contain/control the over-spray. I use the pump spray bottle and it has worked much better for me. I hope that helps you and others.

  6. The spec for treating military clothing is MIL-DTL-44410C. A web search will bring up a .pdf which describes the process for treating clothing.

    The kit provided for doing so includes the equivalent of a gallon Ziploc, a piece of string, and two bottles with 9ml (about 1/3 oz.) 40% permethrin in each. One bottle (I guess the other is a spare) is mixed with 15 oz water in the bag and agitated, the garment is rolled up and tied and placed in the bag, shaken and kneaded to distribute the solution and left to soak about three hours, then hung up to dry. The document says this will last the life of the garment (50 washings).

    I did notice some difference in the permethrin specified and the 36.8% product I’d been purchasing. The 36.8% concentrate has a cis/trans isomers ratio of max. 42% cis and min. 58% trans, whereas the 40% concentrate in the mil spec has 35%/65% ratio.

    Being the inveterate tinkerer, I had to find that stuff and finally found some Gardstar 40% EC (Emulsifiable Concentrate) with the same cis/trans ratio and bought a quart of it. It costs about double what the 36.8% product does. I don’t know if all that makes any difference but I’ll have on hand enough to treat my entire family wardrobe. I was able to fish out of pertinent military documents the supplier for the permethrin in the kits but I couldn’t find a website for that company so I searched for and bought what had the equivalent specs.

  7. So, this is a great recommendation. I have used both the spray and soak methods and moth are effective. And, after some thought, I have another method to apply. We had an un-used 1 gallon plant sprayer in the back shed and my wife suggested we mix up a batch from concentrate and spray our gear. So, 4 ounces concentrate (@ 10%) blended with 76 ounces water yields a 0.5% concentration. We put a blue tarp out in the shade and then carefully layout clothes, foot wear, etc so they are flat and each piece touching the adjacent pieces. Then apply, let dry, turn items over and re-apply. This is the most efficient way we have found (practically zero waste, minimal handling required) plus it is easy to do tents, screen rooms, and other “bulky” items. Jb

  8. You’d never believe I was a math major…

  9. Read the label on the product! To get 1 gallon of desired emulsion,at 0.5% concentration, mix 1 2/3 fl. oz of permethrin sfr 36.8% + 126 1/3 fl.oz.of water to obtain your gallon of mixture. They also list 1.0% and 2.0% emulsion on the chart,up to 192 gallons of finished emulsion. Also their SDS lists 36.8 % concentration, 15% hydrocarbons, and the rest is water. They even tell you not to mix with anything but water. The labels and SDS sheets are quite complete, if you take time to read them before hoseing yourself down! another BOB.

  10. I’ve seen a lot of people freak out about it being poisonous while still liquid. Doesn’t seem possible since a potion of twice the strength of what we’re soaking clothing in (1%) is what’s prescribed for people with head lice.

  11. Thanks Philip for taking the time to let the average guy know how to affordably protect their self and family from mosquitoes, tics and other insects/bugs while enjoying everyday life outdoors. If it were up to big business and regulators no one would know how to do anything but pay for expensive products. I like your DIY approach and will start protecting my family this way. I have so many friends and even family members who now suffer with Lyme disease that when you think about it may have been prevented by using this clothing soak method and some DEET. Great job!

  12. Does anyone have any experience with the effectiveness of Permethrin treatment as protection from no-see-ums?

    And thank you for all of your helpful calculations and advice!

  13. I bit the bullet and did my own permethrin soaking before my section hike (in Virginia) this August. No problems with ticks: hurray. Thanks for the instructions.

    But a question: is there a risk that in rinsing out clothes along the way that some of the permethrin be wrung out? In wringing out some clothing while on the trail, the rinse water seemed cloudy in an unusual way. I wondered weather it was not simply sweat but the permethrin. Could that be possible? If so, it would certainly be a concern both for the protection the clothing provides and for the environment.

  14. After soaking the clothing, can you dry them in the dryer – maybe after they drip dry? Socks can take 3 days to dry if you do not put them in the sun.

  15. I premixed Martin’s 10% permethrin to a 0.5% concentration. I used a clean plastic container. About 1 month later, the permethrin has floating “slime” and some has turned black, almost like a mildew appearance. One of the ziploc bags I used for soaking also had this same black slime.

    Has anyone else experienced this? Any guesses as to what’s causing it? Should this solution be disposed of, safely, or used?

  16. Gotcha … misinterpreted your original reply.

  17. Hi Philip, thank you so much for this super informative post, and to those who have left comments with additional guidance. We are planning to go ahead and try this method. Unfortunately, we are based in the UK and unable to purchase Martins Permethrin – indeed, the options look significantly more limited this side of the Atlantic! We have narrowed our potential options down to two brands: Lignum Pro (62.5) and Permost CT. We think we have a preference for the Permost (its main non-active ingredient is propanediol which seems pretty inoffensive, whereas the inactive ingredients in the Lignum have a few more general health warnings attached). However our main concern is the Permost apparently is ‘microencapsulated’ permethrin, with 50% being large and 50% being small, to give longer lasting results when sprayed on a surface. Appreciate this is completely out of the scope of your initial post, and may not be something you have come across, but just wondered if you had any thoughts on how this might impact the effectiveness when treating fabric?

  18. I ran into an issue with mites infestation in my jome. My question is, can I soak my bed sheets and blankets in permethrine to get mites out of them?

  19. Another use is to spray/soak a bandana, then tie it around your best friends neck (dog) to help keep ticks away.

  20. I've lost my dwarves, my wizard and my way.

    Excel setup (seems to work in LibreOffice Calc as well):
    A1 = % Permetherin concentration you have on hand (be sure to format as a % before typing number in)
    B1 = .05% (ditto pre-formatting)
    C1 = volume of water (in ml)
    D1 = =(C1*B1)/A1 …will give you the amount of concentrate needed in ml

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