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DIYSteve
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PostSun Jun 11, 2017 9:36 pm 
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hatchetation wrote:
obtaining concentrated permethrin (an EPA Restricted Use Product) as a member of the general public is illegal

Illegal? What legal authority supports that claim? I just did some quick research and found no such authority. AFAICT, the EPA has approved permethrin for agricultural uses (e.g. spraying livestock, crop spraying), food handling establishments, pets, clothing and even some medical uses (e.g., lice control). The EPA estimates that more than 2,000,000 lbs. of permethrin is legally used in the U.S. for those various uses. Most of that is agricultural use, e.g. crop spraying, hosing down stock, all of which eventually gets into the aquifer. The few grams by the entirety of hikers treating clothing represents some teensy fraction of some teensy fraction of some teensy fraction of that 2,000,000+ lbs.
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Navy salad
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PostSun Jun 11, 2017 10:25 pm 
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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"
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hbb
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PostTue Jun 13, 2017 4:15 pm 
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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.
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HitTheTrail
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PostTue Jun 13, 2017 4:56 pm 
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hbb wrote:
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.

37:1 would get you close.
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Navy salad
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PostTue Jun 13, 2017 11:06 pm 
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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.
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graywolf
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PostWed Jun 14, 2017 6:58 am 
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Navy salad wrote:
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...

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HitTheTrail
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PostWed Jun 14, 2017 9:06 am 
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graywolf wrote:
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.
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graywolf
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PostWed Jun 14, 2017 9:29 am 
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Can't help myself - it's second nature to me.  Now, if the permethrin concentration was simply 36%, then it becomes very intuitive.

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HitTheTrail
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PostWed Jun 14, 2017 9:43 am 
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Just having fun with you. hockeygrin.gif  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).
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Navy salad
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PostWed Jun 14, 2017 9:50 am 
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graywolf wrote:
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.
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graywolf
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PostWed Jun 14, 2017 10:01 am 
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HitTheTrail wrote:
Just having fun with you. hockeygrin.gif  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.

Navy Salad: You're welcome!

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Schenk
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PostWed Jun 14, 2017 10:56 am 
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hatchetation wrote:
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.

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PostWed Jun 14, 2017 1:51 pm 
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Thanks to all chiming in with suggestions on the dilution ratio, I appreciate the help.  up.gif
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Schenk
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PostFri Jul 07, 2017 12:02 pm 
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OK, so permethrin works well, and if it works, why think of an alternative?
Curiosity.
Has anyone tried any of the other insecticides or repellents commonly used on Farms and Ranches for livestock?
Like this one:
http://www.truevalue.com/product/Farm-Ranch-Supplies/Livestock-Dairy-Supplies/Farm-Animal-Insecticide/Prolate-Lintox-HD-Lifestock-Insecticide-1-Qt-/pc/17/c/2935/sc/2866/50914.uts

Or this one:
https://www.valleyvet.com/ct_detail.html?pgguid=a5d34c1c-516b-4fbd-98c5-4a83d318c421&sfb=1&itemguid=7f5331f5-fe37-4a15-8170-3569ba3abf15&utm_content=35135&ccd=IFF003&CAWELAID=120295250000091148&CATARGETID=120295250000171793&cadevice=c&gclid=Cj0KCQjw4vzKBRCtARIsAM3l8OAUzmbkN63kTZnu5_0e9L3YfDWknMrZDPKgyUFzpjhcZyXNDGmamy0aAq2CEALw_wcB
EDIT -DO NOT USE THIS ONE!

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.

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DIYSteve
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PostFri Jul 07, 2017 2:01 pm 
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Schenk wrote:
Like this one:
http://www.truevalue.com/product/Farm-Ranch-Supplies/Livestock-Dairy-Supplies/Farm-Animal-Insecticide/Prolate-Lintox-HD-Lifestock-Insecticide-1-Qt-/pc/17/c/2935/sc/2866/50914.uts

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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