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. I explain how to do this below.
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 a 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 (tent or hammock) you want to treat or many articles of clothing. Soaking is also likely to provides 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.
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.
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 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. A 32 ounce (1 quart) size bottle of Martin’s 10% Permethrin comes with a built-in measuring cup which is useful for this process.
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.
Precautions. Martin’s 10% Permethrin is a neurotoxin and you do not want to get it on you or inhale its fumes. See the manufacturer’s safety sheet for more information. I recommend wearing protective gloves when working with it, 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 labelled and disposed of as recommended on the product label by the manufacturer. One reader has reported a sensitivity to diluted Martin’s 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.
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, 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 left-over 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.
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.
Liability Disclaimer: The author of this article and website is not responsible 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.
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