“Warm when wet”

Down collapses if it gets wet enough, and then it loses all it's insulative value. Synthetics and wool keep their loft if wet, so there insulative value is mostly maintained. Maybe that's "warm when wet". Another factor is when insulation gets wet, and you wear it, it gradually dries out from body heat. Converting liquid water to vapor which then blows away, requires heat. That is the biggest factor making you feel colder. I know of no published studies but I've measured some of this.

I always say it is more accurate to say wool is warm when damp. That applies to synthetics as well. I don't know how truly warm anything is when sopping wet. :) That's what I find anyway…

Heat of Sorption is a real thing with wool, because the fibers themselves suck up (and eventually) give off so much moisture. Plenty of scholarly discussion available. Whether it is consequential enough in something thin like a baselayer shirt is another matter; frankly I'm skeptical that it is. I find thin wool baselayers warmer than synthetics in relatively mild cool to cold conditions, as they delay evaporative cooling. Over the long term I find them colder in truly wet conditions, and for those trips no longer use them.

This is kind of what I'm getting at. Damp wool is "warm" but on the cool side of warm, but soaked wool doesn't feel like it has any insulating properties and possibly even worse than none at all.

Wool is better than cotton, but I'll vote for polyester fleece and base layers. The advantage with fleece is when soaked it can be wrung out or even shaken to remove most of the moisture and leave some hope of insulating value that your body heat can dry further. Polyester is usually less expensive, easier to launder and lighter, which is why the stuff was developed. Working as designed, wicking polyester base layers will move moisture out away from your skin and fleece can continue to wick and dissipate the moisture. A complete soaking is a system failure scenario, like no rain gear or going for an unplanned swim— things to be avoided regardless of the miracle fiber choice. Getting that wet isn't going to be a "warm" experience. That's time for a dry layer from the wateproof storage in your backpack. Wool soaked to the same level will take a long time to dry. Wool sweaters that still have natural oils can be somewhat water repellent and, although heavy cable knits can trap a lot of air under rain gear. Wool can be very tough and good for socks and gloves.

First watch this video: https://www.youtube.com/watch?v=xYXAvdxbplk Wool absorbs some of it's moisture content in a way where it's not physically contacting your skin. That's why it feels drier when damp, because the fabric near your skin is actually drier. Less thermally conductive? Is that the right term? I find wool base layers to be warmer when damp. Damp would be under a rain shell all day where your perspiration can't evaporate. When totally soaked, I don't know. When water evaporates, you get evaporative cooling. Slowing evaporation is important when trying to keep warm when wet. If you start to get chilled from evaporation, put on a windshirt. It will slow the evaporative cooling while still allowing some evaporation. When you warm up again, take the windshirft off so your clothes dry faster. Wool dries slower which contributes to it being "warm while wet".

I don't have a link, but I've read that the fibers of wool have little "hackles" on them that keep them from laying right against your skin, which helps make the wool a bit warmer when wet. My personal experience is that wool is a lot warmer when wet than just about any other fabric except good synthetic fleeces, which are similar. Wool does take a long time to dry, and if I'm using it just for its insulating properties, I prefer fleece because it wrings drier then dries faster. And it's a little lighter. Wool stinks less, though. Edit: typo

> Does anyone have a link to studies that scientifically break down the different > insulative properties of various insulations like wool, down, and the myriad > synthetics our there specifically pertaining to loss of ability to insulate when wet? No links, but 27 years working as a PhD research scientist in Wool Research. Wool does give off some heat when it absorbs water: that is true. Exothermic reaction. Great claims have been made to this as a benefit for clothing. The amount of heat given off might keep a mouse warm for a few minutes. It will NOT keep you warm for even that long. So why the myth? It is probably VERY old, dating back to when you had a choice between heavy fabric made from greasy wool and light fabrics made from silk or cotton. To be sure, a damp kilt or wool greatcoat will be warmer than a damp pair of cotton undies … Yeah, we saw lots and lots of 'studies', but none of them ever made any practical or scientific sense. It was all marketing spin. Get your wool jumper wet and you are WET, for a long time. Get a fleece jacket wet, give it a good squeeze and a shake, and you start to warm up fast. But don't believe me: try it for yourself. Not far from home though. Cheers

nice video but, he said he couldn't measure the difference between merino and synthetic, but the merino felt warmer. That's subjective and open to bias. My problem is there's little scientific data that you can directly apply to use. Lots of anecdotes like that video and everything on this thread (including my own)

Ok, so, does wet wool lose some of it's ability to insulate? If so, what percentage when soaked? The claim I've heard is that even soaking wet wool will some how retain some ability to insulate, which I don't really believe. Damp wool, sure, I can buy that, but soaked?

How soaked is anything after being wrung out? Sopping wet is miserable no matter what.

Once upon a time… way back in the… er… early 80's I think it was, those concerned with winter survival gave up wool in favor or the new 'pile' pants and jackets. That's because wool was heavier, held more water and took far longer to dry out. But then the marketing of the last several years(15?) came along and began to spin wool… wool stories… to get it selling again. Yes, I know there have been some advances in wool, but I think the original reasons for going to synthetics still apply. billy

Two interesting articles, I think. http://www.dui-online.com/tech_wool.html http://www.straightdope.com/columns/read/108/how-does-wool-keep-you-warm-when-its-wet

on a 5-10C night jump in the shower with yr wool … wring it out as hard as you can and go sit outside now do that with a fuzzy fleece … neither are absolutely pleasant … but one is much more unpleasant and youll hypothermic pretty quickly folks who claim "warm when wet" with wool may have gotten a bit damp, but theyve never been absolutely soaked in it especially when theres no sun to dry it out now thinner wool does dry out a bit quicker than thicker wool … but then the thinner you go the easier it is to get holes ;)

for 25 years I got paid to be outdoors in miserable weather :) my non-scientific observations: wool does a pretty decent job when damp/wet, fleece does even better- both will be better than down or "fluffy" syn when wet the ability to wring and shake fleece out and get rid of water when soaking wet definitely puts it above wool for very wet conditions very thin wool garments, especially wool-syn blends, are nice as base layers- especially on multi-day trips where the odor fighting ability of wool shines

Whut Dale W. sed.