Drysuit undergarment with a collar?

[Storker]

be very careful to be sure that the garments you are using are designed to retain most of their insulating properties when wet.

I don't have the experience you have with diving, but I have more than 30 years of experience in keeping warm in wet and cold climate (I've been wet in freezing and sub-freezing temps more times than I like to remember), and IMO that's impossible. The only fiber that retains any insulation properties even when soaking wet is wool. Which is why you want wool next to your skin. OTOH, having enough loft to keep warm in water at refrigerator temperatures is pretty difficult with anything but thinsulate or similar types of materials. So you need to combine materials, making sure you retain some insulation close to your skin even if you're soaking wet.

 

[dberry]

That's interesting... "back in the day" I was taught wool was the only material that retains some insulation when wet, which explains all the rag wool socks and mittens packed away with my nordic skis and snowshoes. Are there still no new synthetics that can compete with sheep hair?

 

[Keith.M]

Not absorbing water and being able to retain warmth when wet is one of the properties of thinsulate.

Why Do We Use Thinsulate

Cabelas: Materials - Thinsulate

 

[KevinNM]

That's interesting... "back in the day" I was taught wool was the only material that retains some insulation when wet, which explains all the rag wool socks and mittens packed away with my nordic skis and snowshoes. Are there still no new synthetics that can compete with sheep hair?

I've gotten out of my drysuit to find the undergaments pretty darn damp without feeling cold. The only time I really flooded it was in the pool, and I felt the water sloshing about before I felt cold. I'm pretty impressed with the Bare SB base and midlayer. Not totally happy with the drysuit I have from them, but their undergarments rock.

 

[TSandM]

I can't find the article, but I recently read something looking at the insulating qualities of wet wool, and they were negligible. This was a surprise to me, because I'd always heard that wool worked well when wet. It doesn't.

 

[Ken T]

I don't think wool will insulate much when completely wet, but not too bad when damp.

I have not completely flooded a suit yet and find wool has worked quite well for me while being damp from a delaminating drysuit.

I prefer it over the SB midlayer I own.

Two views on wet wool:

The Truth about Merino Wool Technology as Drysuit Insulation

How does wool keep you warm even when it's wet? - HowStuffWorks

 

[Storker]

I can't find the article, but I recently read something looking at the insulating qualities of wet wool, and they were negligible.

Cite, please?

This was a surprise to me, because I'd always heard that wool worked well when wet. It doesn't.

I'd really like to see that article, because it's not only contrary to what I've always been taught, but also contrary to my own (albeit anecdotal) experience.

I did a quick search in the scientific literature, but unfortunately the hardest articles I found were behind paywalls, and even my workplace doesn't subscribe to those journals. However, I found this:

Wool, which is a highly absorbent fiber, has better insulating properties under moist conditions than polypropylene, porous acrylic, and cotton. Heat transfer in moist textiles takes place by conduction, infrared radiation, and distillation. Until the fiber is saturated, the evaporation process is determined mainly by the fiber's sorption properties.

Heat Transfer through Moist Fabrics

Of course, if the garment is absolutely soaking wet, saturated with water and with no air trapped, it doesn't matter which fiber it's made of. It's the air that provides the insulation. However, the curly structure of the wool fiber, with its "scaly" surface makes it retain its loft and thus trap some air even when very wet. And the surface chemistry of wool does a good job of transporting water away from the skin surface even at low levels of physical activity, while "technical" synthetics generally need more body warmth to transport moisture away from the skin surface.

The surface chemistry of the wool fiber, together with microstructure which is very difficult to simulate with a synthetic fiber makes wool a very good - IMO the best - wicking layer at low levels of physical activity. For the next (insulating) layer, I also prefer a good synthetic like Thinsulate, since those garments give a lot more loft and insulation per unit weight (and thickness).

It's all about combining different materials with different properties to get the best combo (or "composite") for the situation. For moderate to high levels of physical activity, a synthetic fiber wicking layer is best, since you'll perspire a bit and synthetics like polypro absorb no water. However, you need a bit of heat production to have good transport of moisture away from the skin. For low levels of physical activity, the structure and surface chemistry of wool makes it better at retaining air next to the skin, and keeping the moisture somewhat away from the skin. However, since wool retains more moisture than synthetics, it's not the best choice if you're planning on perspiring a bit, like when you're doing exercise.

---------- Post added April 15th, 2015 at 10:55 AM ----------

Are there still no new synthetics that can compete with sheep hair?

Don't diss wool. Nature has had millions of years for product development of wool fibers, man has had a few decades for product development of synthetic fibers. If you pay enough, they'll probably be able to make a synthetic fiber with the same type of surface as Nature's masterpiece, but I imagine the process complexity and thus the production costs would be quite prohibitive to commercial applications. Just look at the microstructure of the different fibers:

View attachment 206632

Also, take a look at https://www.pinterest.com/frogwitch/fiber-science/ It's an interesting read