Are You Sitting Comfortably?

You don't get many Gore 'comfort guys' to the pound, in fact they're a rare species altogether with just seven or eight worldwide and just one, single, solitary 'comfort guy' in captivity in the UK.

And yes, we know they sound like something out of a John le Carre novel - 'We passed him over to the comfort guys for interrogation, he sang like a canary' etc. In the more prosaic world of breathable / waterproof clothing though, the 'comfort guys' are the men responsible for assessing every fabric Gore makes to ensure that it's, well, comfortable.

Sitting in Gore's Scottish UK facility, Charlie, the comfort guy looks slightly well, slightly uncomfortable in fact. In le Carre terms he's at the wrong side of the interrogation room being grilled by us about comfort.

Meeet Charlie (left) Britain's one and only Gore comfort guy, he has a passion for waterproofs and moisture vapour permeability no less.

So, Charlie, what's it all about? The first thing you need to know is that 'comfort' in Gore-Tex terms, isn't just about whether something feels nice and comfy. The job of Charlie and the other comfort guys is to break 'comfort' down so it can be assessed as objectively as possible. That means a lot of their tests are for Moisture Vapour Permeability, the ability of a fabric to transmit water vapour which, in turn, is what will keep you both drier and cooler.

It's what us sloppy journalists usually refer to as 'breathability', a word that Chalie hates. 'I hate that word,' he says. Breathability is actually about the passage of air through the fabric, but waterproof Gore-Tex transmits very little air, so think MVP.

What Makes A Comfort Guy? The comfort guys have a mix of qualifications and backgrounds. They include a medical doctor, a physics MSc, a textile engineer, an MSc in aerospace engineering, and qualifications in chemical engineering and biology. Charlie himself has a PhD in chemistry but concedes that really it's all about a combination of 'clothing physics' and, where human testing is concerned, physiology. "I've always had an interest in waterproofs," he says. "And how moisture gets out of clothing." In the past he's worked for Berghaus but his passion now is comfort. And his pet hate? "I hate the term breathability - it's moisture vapour transfer that matters..."

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Part Of The Process

Before Charlie and the other comfort fellas get their analytical mitts on a fabric, it's already been through a whole raft of laboratory tests to make sure the basics are right. Gore uses a renowned laboratory in Germany, the Hohenstein Institute, where fabrics are assessed with teutonic thoroughness and put through ISO tests for breathability as well as abrasion resistance, colour fastness and so on.

The next step is to make the material into a virtual garment and use predictive physiological modelling to predict how it'll perform as a jacket. As an outdoors journalist, a lot of the technical stuff whooshes straight over my head, out of the door and out towards Edinburgh.

What I can tell you though is that the modelling uses data collected from between 500 and 1000 people to work out whether the material will keep them comfortable. At this stage, says Charlie, 'the main thing is body temperature. If you can't lose sweat, your body temperature rises.'

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People Vary

One of the things I've learned from testing outdoors clothing is that there's a big variation in how warm or cold people run, so I ask Charlie about that and, in particular, whether fit people vary more or less.

This is part of Charlie's new venting testing rig. One of only three in the world, it will allow him to assess the effectiveness of different venting arrangements and help to make Gore-Tex clothing more effective.

Interestingly, the data Charlie has access to suggests that fit, trained people sweat more, sweat sooner and sweat more effectively than an untrained sample of the general population, so if you're fit and active, the chance are that you'll run hotter, making breathability - sorry, Moisture Vapour Transfer rates - even more crucial to comfort.

Of course it's not that simple. Other variables like fat levels, circulation, gender, age, aerrobic output, power output and, erm, drugs, will all have an impact on how warm you run.

If you're off somewhere hot, you might also like to know that heat acclimatisation, which takes around ten days, leads to an earlier onset of sweating, more sweat and a lower body temperature. So there you go.

Oh, and just in case you were wondering, it's better to get heatstroke when sunbathing than from exercise, the death rate's much lower...

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Real World Tips We asked Charlie for some tips for jacket buying based on his extensive testing experience. Here's what he suggests if you want to be as comfy as possible: 1. Keep it simple - in particular, pockets with double layers of fabric kill moisture vapour transfer, so look for pockets with mesh liners. 2. Minimise seams - seams use tape and tape isn't breathable. Charlie says that ten metres of tape equals two large pockets with a Gore-Tex lining or 25cm of extra length. 3. Shorter is better - less coverage equals better performance and less overlap with overtrousers. 4. Don't carry maps and other non permeable things in your pockets.... 5. Ideally you want sleeves you can roll up. It's a very effective way of losing body heat fast as blood is pimped through close to the surface. 6. A close fit is more efficient, loose garments are cold and as they flap around, they cause internal convection currents that tend to move warm air away from the body. 7. Venting ability is crucial to comfort, but Charlie has only just started to measure the efficiency of different venting arrangements scientifically. He's built the only rig in the world capable of measuring the localised effects of venting on body temperatures and one of only three anywhere. See picture. 8. Move somewhere dry and cold where moisture vapour transfer rates are higher :-)

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Real People? Not Yet

Meet the mannequin, made of copper, he gets hot and bothered so you don't have to...

If the virtual test results come good then the next stage is to make a basic garment up from the material and take it into the test chamber where it's popped, along with a baselayer, over a heated copper manequin. This, in turn, is dampened and the MVT of the fabric is assessed. The mannequin sits in a chamber at a constant temperature and humidity allowing the calculation of just how much power is needed to maintain the mannequin's temperature.

Assuming that goes okay, it's on to human guinea pigs. If you're thinking it's just a question of throwing jackets at people and asking them how they work, then you'd be wrong.

In fact it's a methodical process using a few people but testing them four or five times to minimise variability. Stick 'em on a treadmill in a chamber with standardised temperature and humidity and measure heart rate and core body temperature. As people vary according to the time of day, caffeine intake and acclimatisation to exercise, it's not as simple as it sounds.

Nor is taking the core temperature. The tests can't be done in the US apparently, since it's not permitted to use a rectal probe. No such problems in Germany...