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#1
Old 04-11-2014, 11:51 PM
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Exact name of PVA "cooling" material and source?

I picked up a couple of "cooling towels" at the dollar store; I'd read about "cooling towels" a long time ago but really didnít believe they were likely to work very well. So yay, I can try these for a buck and if the dollar store version work, then I can be pretty sure the higher end stuff does, too. Well



This material is extraordinary. Even against very warm skin the material is significantly cooler and remains that way. It does this without bulk and without needing to be dripping wet, the two big downsides to the other cooling products I've used. (Cooling products have become absolutely crucial for me now that my primary transportation is my bike: I get very hot very fast, and so does my dog Preston, who is my biking companion most of the time.)

So far the only thing I know for sure is that it is PVA, similar to the kind used for car wipes but with this amazing added cooling ability. I haven't yet run across anything like a brand name for the specific material itself that clearly distinguishes it from the other kind of PVA material, and I would really like to purchase it by the yard, fabric-style, so that I can create my own products instead of having to pay premium prices for finished products that have to be adapted.

The google seems only to find the material as finished products, however. The closest thing to "by the yard" I can get so far is the towels. I continue to do the google and I will probably end up, if you guys can't help, writing to various manufacturers to get answers, but maybe you guys CAN help, cuz you are the Dope, after all.

So will someone swoop in with a link to everythingyoueverwantedtoknowaboutpvacoolingmaterial.com, where they are having a sale on it for a mere $1 a yard? But something less magical and cheap would be okay as well.
#2
Old 04-12-2014, 12:10 AM
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Consumer Reports didn't find them to be any different than common dish towels. Not surprising since one product is just a polyester/nylon blend. The other one uses PVA which is either polyvinyl acetate or polyvinyl alcohol, or just something else altogether. Polyvinyl alcohol is water soluble and would degrade rapidly, and I think it's expensive too. So most likely polyvinyl acetate or just BS. These materials don't have any magic properties. If they cost a buck and you like them then stick with those. The high end versions are probably just more expensive versions of the same thing.
#3
Old 04-12-2014, 12:58 AM
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Quote:
Originally Posted by TriPolar View Post
Consumer Reports didn't find them to be any different than common dish towels. Not surprising since one product is just a polyester/nylon blend. The other one uses PVA which is either polyvinyl acetate or polyvinyl alcohol, or just something else altogether. Polyvinyl alcohol is water soluble and would degrade rapidly, and I think it's expensive too. So most likely polyvinyl acetate or just BS. These materials don't have any magic properties. If they cost a buck and you like them then stick with those. The high end versions are probably just more expensive versions of the same thing.
They are too tiny.

I have the car-cleaning PVA absorbent cloths and while they seem to be almost the same material, they don't get and STAY cool the way the cooling material does, and they feel more rubbery.

I'm seeing lots of different brands, and that's another reason I want to find out about this particular PVA stuff: it appears there may be knock offs that do not work the same way.

I also need to try pushing these a little harder to test how the cooling sustains, and I'm just the gal to pressure test them: A few years ago when I was a YMCA member I used the kind of cooling bandanas that are filled with the gel beads that swell when wet. I would soak them until swollen, and then freeze til solid. I would not only wrap my neck and head with solid ice, I would frozen bandanas into my bra, my pants, anywhere I could. Because the most miserable aspect of exercise for me is becoming hot. I really hate it and would love to be able to to build my own private gym inside a walk-in freezer. Perfect!

What was solid ice at the start of my 30-45 minute workout would be completely melted and unpleasantly warm by the end, so there wasn't even a good way to "restart" them for the weightlifting, they were done until I could freeze them again, while this material becomes cool again the minute you wet it, and that's an enormous advantage.
#4
Old 04-12-2014, 01:18 AM
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I didn't read your link until after I responded. CR didn't test them correctly; it isn't about whether one material will be cooler than another immediately upon wetting, it is about what happens when you put the cool wet material on your warm skin, and that is the miracle aspect of this material: for some reason I assume having to do with the molecular structure science and science and science, the cool water becomes somehow impervious to being warmed by the hot skin it is next to.

I'm kinda surprised that the CR people were so shoddy about this, but I think it's likely that for many people having a cooling towel is very pleasant, but hardly Mission Critical the way it is for someone like me. After all, there are people who actually choose things like Bikram yoga, which is yoga done in a room heated to 105 degrees. This, to me, is something I would expect to be reserved for torturing serial killers, not something people pay to experience.
#5
Old 04-12-2014, 01:36 AM
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Quote:
Originally Posted by Stoid View Post
I didn't read your link until after I responded. CR didn't test them correctly; it isn't about whether one material will be cooler than another immediately upon wetting, it is about what happens when you put the cool wet material on your warm skin, and that is the miracle aspect of this material: for some reason I assume having to do with the molecular structure science and science and science, the cool water becomes somehow impervious to being warmed by the hot skin it is next to.
The flat spot occurs due to
enthalpy (aka latent heat ) of fusion or enthalpy of vaporization

see the following URL for graphs, which display the effect.
http://en.wikipedia.org/wiki/Enthalpy_of_vaporization

The effect is that for the temperature of the wipes to go above one certain temperature, the liquid must boil off first, and when the liquid boils, it takes away that much heat (per gram, as per ISO standards ) the latent heat of evaporization.. So it has the capacity to remove so much heat without a change in temperature, at the boiling point..

There can also be a latent heat of dissolving, where a crystal dissolves into fluid if it can absorb heat. SO the latent heat effect can be at the solid>liquid change, (eg ice in water), liquid to gas (eg boiling water in a pan.. ), or dissolving a salt crystal...

But I suspect the agent in the cooling wipes the OP has that can evaporate on contact with human skin has the name "ethanol". The PVA is the dense type with tiny pores that would not let the liquid drip away.

Last edited by Isilder; 04-12-2014 at 01:39 AM.
#6
Old 04-12-2014, 02:38 AM
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Quote:
Originally Posted by Isilder View Post
The PVA is the dense type with tiny pores that would not let the liquid drip away.
I spent a few hours reading patents and trying to understand this phenomenon, but I don't quite get it. Is this anywhere close?

The towel is really absorbent, maybe due to its microscopic structure -- water doesn't want to leave it. Do tiny pores contribute to cohesion? And then as your body heats the towel, more of the water changes state into smaller water vapor and leaves the pores.

But if the pores are so small, why does the towel absorb any liquid water at all?

----------

About the Consumer Reports test... does that mean that this material is really good at holding onto water until it vaporizes? Whereas a regular towel would keep dripping liquid water back onto the wearer, creating warm puddles?

Would any regular microfiber towel with a high surface area work just as well, or is there something special about the PVA ones?
#7
Old 04-12-2014, 10:00 AM
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Lots of outdoorsy fabrics and stuff for DIY here:

http://rockywoods.com/Fabrics-Kits/Wickaway-Fabrics
#8
Old 04-12-2014, 12:58 PM
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It's polyvinyl acetal. Just google it.
#9
Old 04-13-2014, 04:15 PM
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In regards to the OP, there are some issues that I'm aware of...

When it comes to the differences in microfiber products, there are tons of variables in both resin formulations and manufacturing processes and these differences are no doubt why you find some that work better than others for a given application even though they all are *basically* the same thing.

The devil, as they say, is in the details and the manufacturer of the towels you like has no incentive to reveal his details to you or anyone else and I suspect selling you a "special order" of anything under a thousand yards isn't worth the trouble.

His supplier isn't going to screw him and advertise directly (I sell "Wondertowel" in bulk!), so there is really no way for you to link a particular product to a particular manufacturer and that manufacturer in turn to a wholesaler or distributor who could tell you of a retail outlet like a fabric store.

The other problem is that it's possible this manufacturer is having his fabric made to order in a proprietary formulation and the bulk maker doesn't sell this particular fabric to anyone but him.

I'm afraid the deck is really stacked against you. Most fabric stores these days have microfiber fabrics, but you would have to go in and look at them in person to see if they have what you want and I believe the chances are vastly against you.

They are too tiny.

Sew them together?

Last edited by Ornery Bob; 04-13-2014 at 04:16 PM.
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