The Gear Shop => DIY - Do it Yer Own Damn Self => Topic started by: --ML on September 14, 2009, 09:14:07 PM

Title: Evaporative Cooling For Water Bottles
Post by: --ML on September 14, 2009, 09:14:07 PM
First of all, since this my first post on this forum, I’d like to publicly and sincerely say thanks especially to Mr. Halcon, Mr. McLean, and Mr. Nyerges and to the other principals here for putting this place together. As I wrote in a private email to Mr. Halcon, I think it’s really critical when a Forum gets started that it gets started on the right foot. I hope this place becomes a huge success and sets a new high-water mark for outdoor skills on the Internet. I see many people here whom I respect, and I really hope I can make some worthy contributions here. If there’s anything I can do to help, I hope the principals here will let me know. I hope this remains a positive place which I can enjoy and contribute to for a long, long time.

Thank you all once again, with great sincerity and respect.


Now, having said that, let me do what I do best—drag a forum’s content right down into the abyss. Members here will soon learn that bright lights like Mr. Chrystopher, Halcon, Dude, Kodiak Survival, Tap Code, Grizzly Dave, Mr. McCann, that Lou guy, Mr. Jensen, Mr. Qualls, and many more really set the high-water mark in terms of knowledge while The Nine-Fingered Rat Bastard (aka, yours truly) is the dim bulb who stumbles through life setting the low-water mark.

And speaking of water . . . .

Once upon a time, many of us here were exposed to those round, felt-covered cowboy canteens. If we didn’t use them ourselves, we probably saw them in western movies or on television in shows like Gunsmoke. That felt served two purposes: first, it kept the metallic rattling of the canteen down so a horse was less likely to spook. But more important, if you soaked it in water (or I suppose urine or anything else liquid), it kept the content of the canteen cooler through the process of evaporation.

Or at least that’s what we all thought. Since my goat-like aroma keeps me from getting a date on Saturday afternoon, I decided to see if this piece of old woodsman lore was true, or just that much horse effluvium.

*     *     *     *     *

For the last 40 or 50 years, the US Army has been equipping the troops with a fur-lined canteen holder. You see them all the time, hanging off the trooper’s belts. Originally made out of canvas and later made from nylon, the idea behind the fur lining was the same as the felt on the cowboy canteen, only better since the fur was thicker and really surrounded the whole water bottle.


Yeah, yeah, so does it work?

I took two identical plastic current-issue canteens, filled them both with water at the same temperature, and put them out in the sun on a warm day. One just sat there, while the other was in its fur-lined pouch which had been soaked in water (the photo you see at the beginning of this post). I left them out there for three hours, re-wetting the second about every half hour or so just enough to keep it damp (the canteen pouch has a big draining eyelet on the bottom so it really can’t retain too much). Even I was surprised by the results:

Test Conditions:

Starting Water Temperature: 72 degrees F
Air Temperature: Varied; between 82 and 84 degrees F
Ground Temperature (in direct sunlight): 98 degrees

Each canteen held exactly one quart of water.

Water temperature in plain canteen:


Water temperature in canteen with wet pouch:


Yowzah! That wet pouch hanging in the breeze kept the water 32 degrees cooler, and this on what most of us would consider an only moderately hot day! This was such a surprising result that I drove inland where it was hotter and tried the experiment again. Some more numbers:

Starting Water Temperature: 74 degrees F
Air Temperature: Varied; between 98 and 101 degrees F
Ground Temperature (in direct sunlight): 119 degrees
Water in Plain Canteen after three Hours in Sun: 117 degrees
Water in Canteen with wet cover, hung in sun but in breeze: 75 degrees

That’s a 42 degree difference!

*     *     *     *     *

I’ve been running cross-country this summer, and sometimes it gets pretty hot here in the vicinity of The Spider Hole. I’ve been taking one of these old canteen covers, filling the canteen with cold water and Gookinaid, and hanging it in the trees at the end of my run. After an hour or an hour and a half, the drink is still nice and cool.

Now normally I’m not a big fan of these military canteens. They have small necks and they’re made of dark, opaque plastic, probably so the troops can’t see all the crap that’s floating around in their water (Uncle Sam generally preferring to keep the enlisted personnel in the dark whenever possible). But the same principle can work with any water bottle. A wet towel wrapped around a Nalgene bottle and hung in the wind, some wet canvas wrapped around a beer bottle and left to cool in the shade and the breeze . . .you get the picture.

I think the synthetic fleece with a nylon covering that the US military used in their covers is a really good choice, but there’s no reason you couldn’t use some Polarfleece and Cordura nylon to make a cover for virtually anything. This is how those canvas and flax Desert Water Bags worked for the last 150 years or so.

The important thing is that the cover stays wet and that air is free to circulate around it. If you can hang it in the shade (which I purposefully did not) it’s even better.

*     *     *     *     *

Thank you all once again for the forum. I hope this grows into a wonderful place. And I hope everyone hear realizes that any forum is only as good as its members, and that a positive, helpful, supportive forum is what we should strive for.

Before I hit send, I always ask myself one simple question: Did this post make the forum a better place?

I look forward to learning much from you.

Best regards always,


Title: Re: Evaporative Cooling For Water Bottles
Post by: Alan Halcon on September 14, 2009, 09:55:27 PM
ML, many thanks for the kind words. You're too kind.

Honestly, I feel we all have our strengths and all have something worthwile to contribute. I learn everyday. I enjoy that feeling of excitement when I learn something new.
As always, I enjoy your well thought out posts, and this one is no different.

thank you for your contribution and I look forward to more of your writings.


Title: Re: Evaporative Cooling For Water Bottles
Post by: The Wilderness on September 15, 2009, 12:13:02 AM
Wow ML! Great post. These are the kinds of posts that make forums standout.

Thank you very much.

Welcome to the dirt, I look forward to learning from your posts.

The Wilderness

Title: Re: Evaporative Cooling For Water Bottles
Post by: John McCann on September 15, 2009, 10:09:38 AM

1st, welcome to the dirt!  Good to see you here.

Cool Post (no pun intended).  These type of posts provide interesting ideas and information for our members.

At our camp, we don't have water, so Denise and I always bring 4 - 2.5 Gallon military type containers with water for the students.  We use evaporative cooling by wetting towels and draping them over the water containers.  It does keep the water cooler.

Looking forward to more posts!  8)  

Title: Re: Evaporative Cooling For Water Bottles
Post by: Longrifle on September 15, 2009, 11:48:37 AM

Thanks again for sharing your wealth of knowledge whether we knew it or not.  Like others have said, I try to learn something new everyday and in my line of work, thats a gimmee. I only wish it was survival or self-reliance related. 

I think this forum will be everything you expect and more.  Others will be able to come here and "drink from the well."  Here there is a WELLth of knowledge and good folks. 

I will stand and drink with each and every one them anytime!!!


Title: Re: Evaporative Cooling For Water Bottles
Post by: Dude McLean on September 15, 2009, 01:07:11 PM

 Thanks ML, and this is even a good post,  ;D... We expect nothing less from your fertile brain pan...
 Seeing these things in action is the clincher...

 These simple things are a forgotten "art" , if I can use that word. I recall wetting my canteen down in the deserts in 29 Palms while in the Corps, it made a huge difference.

 At DT09 , I did a class on passive cooling and heating.

 The cooling was how to make a "zeer pot" ... Get a large unglazed flower pot or? a round shape is better if you can find one , instead of the cone shape. With the large pot you get the next size down... Soak the large pot for an hour if you can. Then fill the bottom with about 2 inches of wet sand. Plug the hole first. Place the smaller  in the middle and then pack wet sand all around the sides,
 Once it is even with the top , you place a wet rag of cotton, or burlap over the top... Oh place in your veges or fruit etc.
 This will keep your eggs, fruit, veges etc very cool, .... Keep it in the shade, if a breeze can get to it, so much the better.

 This is  good for camping or at home ... Camping, it frees up room in your ice chest for more inportant things , like beer.
 This means you need less ice, or you are not forced to make a run as often, etc..
 At home it frees up space in your fridge and looks good on a counter etc...

 I did one other cooling system and one heating heating system...

 Again thanks to ML, glad you are here...

 Dude...check yer6....


Title: Re: Evaporative Cooling For Water Bottles
Post by: Kodiaksurvival on September 16, 2009, 06:08:07 PM
Thanks for the thoughtful post. Hope the trail is treating you well!

Title: Re: Evaporative Cooling For Water Bottles
Post by: recycler4570 on October 05, 2009, 12:05:07 AM
Thank you, and great to see you here!
That was an amazingly well set up demo!
I'd also never thought of using fleece as a cooling cover. i've got a buch of scraps sitting around somewhere.

Title: Re: Evaporative Cooling For Water Bottles
Post by: Grizzly Dave on October 05, 2009, 12:58:37 AM
Great post my friend and always kind words included.
I hope you are faring well and the spider hole is warm this winter.


Title: Re: Evaporative Cooling For Water Bottles
Post by: MountainManIndy on October 05, 2009, 11:07:10 PM
 :thumbsup: Great reconfirmation of my younger days of using one of those felt covered canteens... (playing cowboys and indians of course)...

Made one of the 'Dude-Flowerpot-Cooler's... when it was 100+ here in Riverside, CA.  Put it in the shade on my patio. Start - Ambient air temperature - 112 Degrees Farenheit. Temperature inside the inner pot... 68-72 Degrees Farenheit... made for a cool can of beer... especially considering the outside temperature.


Title: Re: Evaporative Cooling For Water Bottles
Post by: Alan Halcon on October 07, 2009, 08:38:15 PM
The Zeer Pot is a cool thing of things, Indy, isn't it?

Title: Re: Evaporative Cooling For Water Bottles
Post by: MountainManIndy on October 09, 2009, 10:29:13 PM
Yep, the Zeer pot - or Dude's potted-pot-cooler... is not only neat... but anything that keeps a can of beer cool on a very, very hot day... FABULOUS  :thumbsup:

Also - looking forward to the weather cooling down, so I can try out the Dude's - Inverted-triple-pot-carriage-bolt-washer-spaced-single-candle-radiant-heater... NOW THAT should be just as neat (and yes, Dude I've all ready put it together with NEW, untainted with water, unglazed ceramic flower pots... and steel carriage bolts and washers - nooo galvanized or aluminum stuff). It'll be interesting to test the temperature radiating from the contraption in concentric circles of distance... the physics is certainly sound... (OK -- you can separate the engineer from the lab, but ya can't separate the engineering out of the engineer)...  

I'll let you know how it works - later in the season...  :thumbsup:

Title: Re: Evaporative Cooling For Water Bottles
Post by: Alan Halcon on October 10, 2009, 10:49:19 AM
admittedly, I've never tried the flower pot thingybobby, even though I've known about it for some time. I look forward to a full report. :thumbsup:


Title: Re: Evaporative Cooling For Water Bottles
Post by: Dude McLean on October 11, 2009, 12:19:32 AM

 The steel parts are the way to go.... Just have to space it ...

 All it really is a is a space heater... Try it in a tent.. or a small closed room, with some air so you dont up and die..

 It should at the least take the chill and damp out of the air..

 What I really like about things like this,is it is something most of us have heard about,read about,seen pictures, but never ever did it..

 The doing is the ticket... otherwise it is just a damn theory....


Title: Re: Evaporative Cooling For Water Bottles
Post by: John McCann on October 11, 2009, 05:23:07 AM
Nuthin worse than just a damn theory....  ???


Title: Re: Evaporative Cooling For Water Bottles
Post by: FigureCarver on October 13, 2009, 03:55:13 AM

Welcome to the Dirt.
Thanks for sharing

Sig :sig:

Title: Re: Evaporative Cooling For Water Bottles
Post by: LMagna on October 26, 2009, 06:33:52 PM


If you ran the results using a dry cover on one canteen and a wet one on the other or do you think the dry cover would just slow down the warming of the liquid and the eventual results would be pretty much the same? Or would just the ?blanket? insulation keep the contents cooler than the ambient temperatures?

If my old memory serves me right, the water in my canteen during my past escapades in Uncle?s overseas fun spots became fairly tepid to say the least even with the doors removed and the constant down wash from rotor blades. 

Maybe I should have hung the canteen on the outside of the chopper during monsoon! Then we would have looked like those guys who drove tanks around, junk hanging from everywhere! {:^)

Title: Re: Evaporative Cooling For Water Bottles
Post by: travellingJeff on November 30, 2009, 08:50:44 PM
ML  You've shown me a way to keep beer colder, longer.  A saint you are, sir :)  Great idea, I'll give it a whirl next time!

Title: Re: Evaporative Cooling For Water Bottles
Post by: wildman800 on December 01, 2009, 11:46:17 AM
Hanging a canteen or other vessel (especially ceramic) in the shade where the breeze can circulate around it will also keep the contents cooler.

This is why our neighbors south of our border used to (may still) keep ceramic water jugs under the eves, outside of buildings, in the shade, in the breeze.

I have found that the westerns (silent and talking), from the early 20th Century, were close enough (time wise) to those "wild west days" that there is much historical fact that was included in the backgrounds because the audience, who knew better, would not have tolerated the lack of detail.  Please remember that the last Confederate Veteran did not die until the 50's - early 60's.

Check out the "poor man's automobile air conditioner": a bucket filled with ice that had a towel hung from it upwards so as to catch the wind coming from the side vents that used to be a part oif every automobile.  The water from the melting ice would be absorbed by the towel, the wind from the vent would be cooled by the ice water soaked towel, voila, cool moist air inside the vehicle.

Title: Re: Evaporative Cooling For Water Bottles
Post by: black arrow on December 01, 2009, 08:55:11 PM
Thanks for the post, ML.

Good visual aids, helps the point sink in.