I rode into work this morning wearing a top made with Gore Windstopper. Often I might wear just a fleece instead. I noticed today that I was distinctly less “glowing” when I got into the office, despite putting some oomph into the pedals this morning.

Does the Gore layer in the Windstopper actively draw warm/moist air away from the body or is it as “passive” as a fleece layer might have been (both are the same thickness and similar polyester outer fabric) and so was I simply deceived this morning?

Similarly, do breathable waterproof layers actively draw heat and vapour out from the body as well as keeping you dry, or do they just “let” the heat and sweat out whilst simultaneously keeping you dry?

It depends on the fabric – nothing is going to suck heat and sweat out of you, the way Windstopper works is that it’s an air permeable PTFE membrane, so if there’s a temperature/humidity difference between in the inside and the outside of your shell layer, air will tend to move outwards. Whether it wicks moisture away from your skin depends on other things, what the backer fabric for the membrane is for example and whether you’re wearing a wicking baselayer/mid-layer underneath.

Other fabrics work differently, a PU-based coating or membrane will be hydrophilic, so tends to attract water into it before moving it across the coating or membrane.

Also waterproof fabrics have relatively low thermal insulation values compared to fleece, which is designed to trap warm air and hold it close to the body.

Blah… so it’s yes, sort of, it depends, maybe…

And it will all depend on other factors too – how hard you’re working, the humidity of the outside world, temperature etc. Generally breathables find things easier in cold, dry environments than milder, damp ones. Unfortunately the UK is mostly relatively mild and moist, so stuff that works well on, say, an alpine glacier, may not be as effective on a damp day in Scotland.

Generally breathables find things easier in cold, dry environments than milder, damp ones.

I think that might have had the greatest effect this morning, Its cool and dry in the air here in London this morning.

I wasnt wearing any fancy wicking base layer, just a work shirt (cotton)

EDIT: Oh, and thanks BWD, interesting post.

The fibres in Windstopper actively push water along their length from the inside to outside (under a microscope you can see their wee arms doing this). Fleece fibres sit on their fat ass, though they did the same as Windstopper fibres when they first came out, now they’re fed up because they’ve been overtaken.

Seriously…can any fabric “actively” move moisture in a meaningfu/significant way?

I think the point with WS is that it’s got much less insulation, as the windproof-ness is what keeps you warm, and that should let moisture through more quickly?

The only waterproof fabric (which Windstopper is – just the lack of taped seamed stop the garment being waterproof) which actively moves moisture is Nikwax Analogy. All the other fabrics are membranes or laminates which depend on osmotic pressure (hot+damp to cold+dry) to allow the movement of moisture outwards so their breathability is simply a matter of how much they restrict the movement of moisture – and compared to merely breathable fabrics (i.e. ones that rely on a tight weave to stop air) they restrict this much much more.

The fibres in Windstopper actively push water along their length from the inside to outside (under a microscope you can see their wee arms doing this)

I’m not sure they do, the backer fabric might wick like that, but the Windstopper membrane is just EPTFE – teflon basically – so it’s not made of fibres. Windstopper’s a sandwich, the membrane sits in the middle, there’s a face bonded to the outside and a backer bonded to the inside. The fabrics on either side affect the wicking performance and the breathability, as does the amount of glue used to stick it all together – microscopic dots of the stuff which isn’t breathable, so the more of it there is, the less breathable the fabric tends to be.

Seriously…can any fabric “actively” move moisture in a meaningfu/significant way?

Some fabrics wick better than others. There are plenty of polyester base layer fabrics out there which are designed so the structure of the fabric tends to move moisture outwards, so yes. PU coatings tend to suck water in as they’re hydrophilic.

Anyway, in a sense, all this is academic because a hard-working cyclist is likely to produce more sweat and heat than any waterproof – the Windstopper membrane btw is effectively waterproof – can cope with, so the difference between a very breathable, high-wicking system and a less breathable one is mostly that you’ll take slightly longer to get steaming wet and dry out a little quicker when you do.

Or that’s my take on it anyway. Sorry, dullness abounds 😉

The only waterproof fabric (which Windstopper is – just the lack of taped seamed stop the garment being waterproof) which actively moves moisture is Nikwax Analogy.

Technically – in lab tests – Analogy isn’t waterproof because it allows water through it under pressure, try sitting in a puddle wearing Paramo trousers and the pressure of your body weight will lead to leakage. In practice it is waterproof, but the downside is that the pump liner adds extra insulation, so it doesn’t always suit folk who run hot and sweaty.

Seriously…can any fabric “actively” move moisture in a meaningfu/significant way?

If you use a pertex top, and get a bit hot, you can sometimes see where the fabric is in contact with the body (inside elbows etc) get damp and that dampness very rapidly spread across the surface of the fabric (which it’s designed to do) to speed up evaporation.

Go to any outdoor shop and mention Paramo/Analogy.
Watch as the staff recoil in terror and run away from you.

Interesting BWD – I was kidding with the “wee arms” comment BTW.

Pertex does seem pretty breathable, I just hate the feel of it next to my skin, but over a base-layer it is v.warm when you are exercising.

I have a number of “windstopper style” garments which I think work well, I do wonder if they are made the same way and how breathable they are compared to each other. Maybe I should investigate the tightly woven style.

[hijack]CFH – you in town today?[/hijack]

I cant stand paramo kit. Looks like saggy geography teacher clothing that would get soaking wet in seconds 🙂

Technical Fabrics – how they work…

Not as well as the marketing would have you believe.

[hijack follow up]I am, Stoner, but am busy. Will keep Tuesdays in mind, but next two I’m away (Frankfurt then Paris) [/hijack follow up]

Paramo screams red-socked rambler to me, the very person who feels they own the countryside to the exclusion of everyone else. As such, I hate it with a passion!

eVent and Pertex certainly seem the most breathable to me, with Gore WS coming in a close 3rd. Others have mentioned the evaporation piece above, and I would agree. When working really hard in dryer conditions, I’ve seen moisture develop on the outside of my jacket/gloves/whatever. That moisture then evaporates, which I would imagine makes one cooler. However, it’s better out than in, eh?

heat and capiliary action (or some similar effect) mean some jackets can draw moisture away from the body and keep you feeling drier, but none of them are ‘waterproof’ types of top. ime goretex etc is good at keeping rain off for extended periods but it kills the wicking and breathing effect of other layers though. it just doesn’t breathe fast enough as it’s priority is waterproofing.

try wearing a Montane or Buffalo pertex/pile when on the bike in colder weather and you’ll feel almost dry pile next to the skin, and a damp pertex outer layer as the sweat seems to be pushed through by your body heat and the way the moisture is handled by the pile layer. evenm in the rain you’ll stay pretty warm and dry-skinned. add a merino base layer as required. after all this type of top is basically a synthetic animal skin reversed – proven old technology 😉

polyester base layers / man-made tops + goretex jackets are something that i avoid like the plague, a sure way of ending up feeling over-heated then cold and clammy when you stop.

“Paramo screams red-socked rambler to me, the very person who feels they own the countryside to the exclusion of everyone else. As such, I hate it with a passion! “
unfortunately the best functioning gear has the lowest style appeal – probably cos they don’t sell based on marketing / tech BS and only on user recomendations?! you’re missing out.. it’s very good kit. look at what most mountain rescue teams use, it’s rarely super-techy north face kit and quite often buffalo or paramo gear. Montane make some really well thought out pertex/pile stuff now too. shame none of it is bike-specuific as a lighter weight Extreme jacket would be awesome for general winter riding.

Pertex is less breathable than you might think, it’s a very tight weave – originally it was parachute fabric, so the idea was to trap the wind. One fabric that does work really well is Pertex Equilirium, it’s the stuff Rab uses on the outside of VapourRise clothing and is wind resistant, but wicks and breathes appreciably better than normal Pertex. VapourRise, fwiw, does a Buffalo-type gig but with less insulation and bulk.

Generally you tend to trade weather protection for breathability with ‘soft shell’ and weather resistant fabrics – the trick is getting an idea of what suits you. I run quite hot and find Paramo hopeless on the bike at any temperature above zero?C, but if you run cooler, it may work better for you.

Paramo works very well for UK-type winter mountaineering, but the cut for their stuff is kind of baggy and not particularly beautiful.

Paramo screams red-socked rambler to me, the very person who feels they own the countryside to the exclusion of everyone else. As such, I hate it with a passion!

You’re an odd chap aren’t you.

I hate the cut and look of most of the Paramo stuff. Despite that I still have a couple of their smocks and a pair of their trousers because it just works so damned well for walking and skiing in the foulest of weathers (and especially when the weather is being random!) I don’t wear the Analogy stuff for MTBing unless it’s too warm for a Buffalo shirt but too wet for just a windproof/base layer combo, simply because I don’t want to wreck such a good and expensive garment if I crash.