McNair Mountain Shirt

Sports technology: outdoor fabrics

This month's sports technology feature looks at the versatility of manmade fabrics versus the dependability of natural fibres. Is 'back to the future' the way forward?

When I first started venturing into the mountains you generally had two options if it started raining - stay inside and stay dry, or go outside and get wet.

Yes, we had 'cagoules' (whatever happened to them?) but they had none of the waterproof and breathable qualities of today's rain wear. They had one or the other, which meant that if your jacket was waterproof, it wasn't breathable, so you'd invariably get soaked from the inside due to perspiration, or if it was breathable, it wasn't waterproof.

Such inconveniences didn't just bring discomfort; they could also be dangerous since a wet climber eventually becomes a cold climber, which can lead to hypothermia.

So when the US company W Gore and Associates introduced a waterproof and breathable fabric in the late 1970s, mountaineers and outdoor folk around the world let out a collective cheer.

This marvellous new fabric consisted of a porous form of polytetrafluoroethylene (PTFE), with a micro-structure characterised by nodes interconnected by fibrils, and it was christened 'Gore-tex'.

Rise of Gore-tex

Gore-tex has become the world leader in the manufacture of waterproof and breathable outerwear, with around 70 per cent of the market estimated to be worth over $1bn.

Gore-tex fabrics are used by a wide range of well-established outdoor clothing manufacturers such as Patagonia, The North Face and Arc'teryx, and the chances are that if you've bought a quality waterproof/breathable outdoor garment in the past few years, it will incorporate a Gore-tex fabric.

Today's Gore-Tex outdoor apparel is typically based on thermo-mechanically expanded PTFE and other fluoropolymer products. Gore produces a range of fabrics designed for different types of outdoor activity. Lightweight, hard-wearing 'Gore-tex Pro', for example, is for intense activity with varied output levels and prolonged use such as mountaineering, whereas 'Gore-tex Active' suits continuous, high-output activities such as cross-country skiing thanks to elevated breathability and its comfort-factor against the skin.

At the heart of the products is a thin, porous fluoropolymer membrane which has about nine billion pores per square inch. Each pore is approximately 1/20,000 the size of a droplet, making it impenetrable to liquid water while still allowing the more autonomous water vapour molecules from perspiration to pass through. It is also windproof, which is important in preventing cooling due to wind chill.

This membrane is bonded between a durable outer shell and a high-performance lining, which wicks away moisture from perspiration. In addition, all seams are sealed as well as stitched, since, as Gore points out, "every stitch is a potential leak". This may seem a straightforward process, but the tape is actually applied by specially trained manufacturers in certified factories.

Finally, a fluoropolymer-based durable water repellent (DWR) finish is applied to the outer face of the fabric which helps prevent it 'wetting out' – this is where the face fabric becomes soaked with water, reducing its breathability. Although the DWR makes rainwater 'bead' and run off the fabric, it isn't responsible for making it waterproof.

High-end Canadian brand Arc'teryx works closely with Gore-tex to produce some of the best outdoor garments on the market. The company's apparel design director Carl Moriarty says: "Our key focus is to create lighter, stronger, drier products that are beautifully crafted and provide dependable performance in the harshest conditions, which means we're constantly pursuing new leads on how to further these objectives. This results in a premium price, but we're confident that there is a market that appreciates our efforts."

An example of this is their new 'Veilance' fabric, which combines Gore-tex Pro with an insulating layer to provide waterproof, breathable, warm and lightweight garments. This is used in a new premium range of apparel for this winter with prices of up to £1,400 for the top-of-the-range Patrol IS jacket.

Moriarty also points out the importance of field testing: "Concepts are constantly tested among staff, sponsored athletes, industry professionals and members of our broader outdoor community to ensure that they are relevant to our consumers and provide a clear benefit."

Some clothing manufacturers, such as Colombia in the USA and Keela in Scotland, produce their own versions of waterproof and breathable fabrics. However, the University of Leeds found that no fabric remains breathable in cold, wet conditions after 60 minutes (international test standards are set in dry conditions at temperatures of 21°C and above). Keela solve this with their 'System Dual Protection' fabric featuring a double layer with an 'air gap'. The tough, durable waterproof and breathable outer layer ensures the garment can handle wear and tear while a lightweight inner layer creates the 'air-gap' to provide a natural thermal barrier, protecting against heat loss. Keela's designs are made more specifically for a mild, wet climate such as that of the UK.

Back to basics

Despite the current vogue for high-tech, manmade fabrics in the outdoor clothing market, there has been a return to traditional materials and production methods in the last few years.

Merino wool has now become standard issue as a base or mid-layer for outdoor types since it retains heat well; it breathes, it remains warm when wet and it doesn't smell when it gets dirty – especially important if you're sharing a tent with someone halfway up a remote mountain.

McNair Mountain Shirts has taken this one step further with the launch of heavyweight wool shirts designed to be worn as an outer layer. These are hand-crafted in West Yorkshire using recycled merino wool and traditional manufacturing practices that would have been recognised by my grandparents, both of whom worked in the wool trade over 50 years ago.

In brief, the shirts are made using traditional weaving, milling, raising and steaming techniques to create an outer layer which is warm, windproof and weather resistant. While not totally waterproof, it requires one hell of a downpour for water to get through the fabric. Since it's designed for snowy conditions, the fact that the shirt isn't 100 per cent waterproof isn't a major issue since snowfall rarely soaks a garment in the way that rain does.

The shirts have a very stylish cut along with superb attention to detail in the construction process. They've received rave reviews from the outdoor world despite the £350-plus price tag.

Company founder Neil McNair explains what made him decide that 'back to the future' is the way forward for his company. He says: "A major reason for high-tech fabrics swamping the market is that marketing messages have focused on the absolute waterproofness of them, the underlying assumption being that any water ingress would be disastrous. This ignores the effect of sweating, and has led to technical fabrics being worn where it is unlikely to rain, but where you can get still get damp due to perspiration.

"Our shirt allows wearers to stay in touch with the weather around them rather than block it out completely – it's a more comfortable and connected place to be in our opinion. And our customers also appreciate the attention to detail and traditional skills and techniques that we use in the manufacturing process."

McNair says that natural fabrics have less of a carbon footprint, which is also appreciated by customers. "We have a relatively small carbon footprint because we have set up our own manufacturing unit, we source all materials and services locally where we can and we use recycled materials wherever possible.

"It seems odd to us that a shirt from a supposedly ethical outdoor brand may well be designed in the brand's home country but the fabric could be made on one continent, the trims may come from a second and it could be sewn on yet another."

A third approach to outdoor fabrics is that of Cornish surf-wear manufacturer Finisterre, whose fabric innovation relies on blends of manmade and natural fibres.

Debbie Luffman, buying and source director, says: "Over two-thirds of the Finisterre clothing range contains wool – we are seriously into the natural fibre for its softness and thermo-regulating properties. But over the years we've found that wool's performance can be extended and improved by blending it with polyamide.

"Our latest wool developments use core spun yarns, which consist of a manmade durable and moisture-wicking core, wrapped with a soft and insulating merino wool cocoon".

So, with the current mix of high-tech and traditional available, there's pretty much something out there to suit everyone looking to stay warm and dry in the wind, rain and snow.

I asked Arc'teryx's Moriarty where he sees the industry going: "For years the technical outdoor apparel industry has chased fabric breathability as the predominant factor in comfort, but in recent years we've seen a shift towards more energetic, more intense outdoor activities with people looking to move faster and cover more ground. "With this shift, we'll see a focus on a more holistic approach to thermal regulation in clothing rather than just a focus on vapour transfer, with the goal of working through a broader range of intensity and weather with minimal adjustments to your clothing system."

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