I always wash my permethrin-treated clothing separately using just cold water (based on a tip from BigSteve) and no detergent (although sometimes I'll use a scrub brush to get stubborn dirt off, like around the cuffs or the collar).

Edit: Correction -- formerly "BigSteve", now "DIYSteve"

I used up my pint of 10% solution last year, and just picked up a bottle of 36.8% solution for reapplying.

I suck at math and can't find an appropriate conversion calculator online. Can anyone help me out with the dilution ratio? I used the standard 9:1 ratio for the 10% solution, and had good results with that, so I am looking for a similar end product out of the 36.8% solution.

I used up my pint of 10% solution last year, and just picked up a bottle of 36.8% solution for reapplying.

I suck at math and can't find an appropriate conversion calculator online. Can anyone help me out with the dilution ratio? I used the standard 9:1 ratio for the 10% solution, and had good results with that, so I am looking for a similar end product out of the 36.8% solution.

I use 1 tablespoon of the 36.8% permethrin to a 12 ounce spray bottle, which I figure gets me close to a 1.5% concentration.

The math I used is as follows: 1 tablespoon = 0.5 ounce, so 1 tablespoon of 36.8% permethrin in a 12 ounce bottle, where the remainder of the spray bottle is filled with water, produces (0.5 ounce x 36.8%)/(12 ounces) = 1.53%.

So, assuming a 12 ounce spray bottle, if you only wanted a 1.0% solution, you'd use 2/3 of one tablespoon, or 2 teaspoons.

I use 1 tablespoon of the 36.8% permethrin to a 12 ounce spray bottle, which I figure gets me close to a 1.5% concentration.

The math I used is as follows: 1 tablespoon = 0.5 ounce, so 1 tablespoon of 36.8% permethrin in a 12 ounce bottle, where the remainder of the spray bottle is filled with water, produces (0.5 ounce x 36.8%)/(12 ounces) = 1.53%.

So, assuming a 12 ounce spray bottle, if you only wanted a 1.0% solution, you'd use 2/3 of one tablespoon, or 2 teaspoons.

Navy Salad's formula will serve you well - I just ran his formula on a scrap of paper. I'm a pharmacist and do this type of calculation all the time. If you assume 30ml per ounce, 12 ounces = 360ml. One teaspoonful = 5ml, so two teaspoonfuls = 10ml. Using 10ml of the 36.8% permethrin will give you 3.68gm. Add that to 360ml of water (370ml final volume) and you get a 0.99% solution.

To be exact 1 fluid ounce = 29.6ml, but we're not doing chemotherapy infusions here...

One teaspoonful = 5ml, so two teaspoonfuls = 10ml. Using 10ml of the 36.8% permethrin will give you 3.68gm. Add that to 360ml of water (370ml final volume) and you get a 0.99% solution.

360ml : 10ml to me is the same as 36:1

It seems like you are going through a lot of gyrations to get there. But then I am just a simple farm boy.

Just having fun with you. Actually your explanation would make it easier to mix up in small amounts. Thanks. I may use it myself if I get a jug of 36.8% (which I may do).

Navy Salad's formula will serve you well - I just ran his formula on a scrap of paper. I'm a pharmacist...

Thanks for double-checking me, graywolf! I took enough chemistry in college to remember sometimes these calculations can take a tricky turn (like with pH problems), so this gives me more confidence.

Just having fun with you. Actually your explanation would make it easier to mix up in small amounts. Thanks. I may use it myself if I get a jug of 36.8% (which I may do).

Hey, I didn't find your post offensive at all - some of the best life lessons I've learned have been from farmers, loggers, folks in the trades, etc. I'm thinking of picking up some of this strength myself.

I linked to that page because it has an interesting caution about not washing permethrin-treated clothes with other clothes because you probably don't want your underwear treated.

That seems like you are taking some statements out of context, intentionally or not.
If you read the entire paragraph you will see that the reason you don't treat underwear is because outer garments are what the insects come into contact with, not because you don't want your naughty bits to become contaminated...which seems to be what you are alluding to.

-------------- Nature exists with a stark indifference to humans' situation.

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-------------- Nature exists with a stark indifference to humans' situation.

Now, I am not promoting the use of any of these; I am only asking if anyone has tried them, or knows if they are safe enough for use on clothing.

EDIT AGAIN: Never mind...it looks like most of these use Phosmet and judging from the notes to veterinary services are not a good idea for humans to use on clothing. And this is not to mention how toxic it is to bees and other pollinators.

-------------- Nature exists with a stark indifference to humans' situation.

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-------------- Nature exists with a stark indifference to humans' situation.

AFAICT the generic name is phosmet, an organophosphate insecticide.

Per quick Google research I don't see any history of using phosmet on humans. Cf., Permethrin, which has been used on humans for decades in lotion and shampoo form for scabies and lice.

I didn't see anything re spraying phosmet on clothing as a repellent. I did see some studies re farmers' dermal exposure to phosmet.

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