Temperature and moisture management is a great topic for active sportswear, outdoor clothing and institutional clothing as well. In this article by Claudia Ollenhauer-Ries of Germany, focus lies on clothing for cold environment: winter sports, expedition, working outdoor et al.
There are several aspects to be considered, when the function of a jacket or trouser is to keep warm while letting the moisture out:
- a layering system of underwear/legwear + middle clothing + outer shell;
- special fabrics trapping the air as insulation, i.e. hollow fibres, non- wovens, fleece;
- wind stopping membranes which allow evaporation of moisture;
- phase change materials (PCM);
- design of the garment.
Layers of Garments
[bleft]The latest generation of hollow fibres have more than one hole and are texturised. The ideal texture is spiralled in order to trap the maximum amount of insulating air.[/bleft]
The purpose of layering is to trap the air, which is a perfect insulation, inside and in-between the garments. Dense fabrics and membranes keep off the cold wind. The problem arises due to the moisture evaporated by the wearer – even without physical effort; the air gets humid, the fibres get wet, and the wearer feels uncomfortable.
Specialists suggest wearing layers with different functions. For example, close to skin – soft hydrophobic fibres combined with hydrophilic fibres on the outside will pull the moisture away from the skin; middle layer: a knitted/warp knitted fleece made of polyester which will trap the air and absorb a part of the moisture.
A classic alternative is pure wool knitted sweater, as wool can adsorb up to 33 percent of its weight of moisture without feeling wet. The inconvenience: higher weight and a longer drying time of wool compared to man – made fibres. Wind and water stopping shells allowing moisture transition would make the outer garment.
Today, we find many different types of these garments and some product brands have more than 30 years of existence – think of Gore-Tex, which was commercialised in 1976, while others are recent developments – Phase Change Materials (PCM), for example. The interesting thing is that the cooperation of the brands, clothing manufacturers, fabric producers and fibre companies is getting very close resulting in much specialised products. Mere dropping some brand names of high-tech clothing manufacturers works this way: The North Face/USA, Helly Hansen/Norway, Aigle/France or Vaude/Germany for outerwear, Odlo/Switzerland and Trerè/Italy for underwear.
The classic down fillings have their ‘good old things’ charm and have excellent performance value where warmth and moisture management are required. The advantage of high quality downs from goose or duck is still unbeaten by man-made fibres. An important sign of quality is the loft, the ability of the down to puff up after compression. The loft is measured in cuin: a medium value is 500 cuin, a good quality is 600 cuin and the top quality 730 cuin. Usually, downs will be mixed with small feathers, which will make the insulation layer more stable. But downs have some disadvantages: price, drying time, no warming while wet and allergic risks.
The latest generation of hollow fibres have more than one hole and are texturised. The ideal texture is spiralled in order to trap the maximum amount of insulating air. Hollow fibres are used in nonwovens for all kinds of insulations and as small balls for bedding. A famous brand for insulating nonwovens is Thinsulate by 3M/Germany.
Fleece is a fairly new product. Malden Mills/USA launched it in 1979 under the trademark Polartec. Another famous supplier is Pontetorto/Italy with its brand Technopile. Fleece is a warp knitted fabric with loops on both sides. The loops are cut and brushed. The main fibre is Polyester; the weight varies between 100 and 500 gms/m². The first fleeces were just plain piece dyed. Today, we find also jacquard designs, melange yarn effects, structures by knitting and/or cutting, bi-coloured fleece having one colour on one side and another on the reverse, prints and blends with cotton and wool. The main advantages are the light weight, softness, warmth and fast drying.
Critical points are pilling effect and return to bulkiness after compression. The basic articles will not be wind-fast or water repellent – special finishes and combinations with membranes allow even this. The trigger word for this combination of membranes and fleece is ‘soft shell’.
W.L.Gore Associates/USA and the menswear producer Brinkmann/Germany used with maximum advantage the concept of air trapping for insulation in the Airvantage jackets and vests.
The body of the jacket consists of a number of chambers which can be filled with air according to the need of the wearer. The more air inside, the more the insulation effect. The Airvantage jacket won the reputed Design Award of Germany in 2006.
Stop! Wind and Rain
Next to very densely woven or knitted fabrics and finishings or coatings, membranes are an effective shield against wind and wetness. The effect of the wind chill is widely known. Here’s the Wikipedia explanation: “Wind chill is the apparent temperature felt on exposed skin due to the combination of air temperature and wind speed. Except at higher temperatures, where wind chill is considered less important, the wind chill temperature (often popularly called the “wind chill factor”) is always lower than the air temperature.” Therefore, the wind must be kept outside by the outer shell. Also, the wet from snow and rain must be rejected. That’s what the normal membranes do, while allowing the body moisture to get out of the warming system.
The state-of-the-art membranes do even more, as these examples show:
- Gore Micro Grid Backer Technology was launched in September 2007. It is a 3-layer Gore-Tex Pro Shell. The secret behind it is an exclusive weave design that is extremely breathable, abrasion resistant and lightweight, offering comfort for wearers participating in activities like mountaineering, rock climbing, ice climbing and expeditions.
- Transactive, a joint development of Sympatex/Germany and Vaude/Germany, is a system of membranes which can transport the sweat in its liquid form from inside to outside. The claim: The liquid sweat will be pulled away from the skin 13 times faster than with conventional membranes. The moisture management will be enhanced by 40 percent compared to the conventional membranes.
- A product of Toray/Japan is Entrant Dermizax, a non porous, wind and water repellent laminate, which increases the moisture transportation when the micro climate is heating up. The fabric utilises its ultra thin monolithic membrane’s polymer molecule movement to efficiently absorb perspiration vapour build-up on the fabric’s inner surface and disperse it throughout the fabric.
- Schoeller/Switzerland C_Change membrane has a similar effect. In doing so, it reacts in a way similar to a pine cone which opens and closes in response to different weather conditions. As soon as the ambient temperature rises, or greater moisture is produced as a result of body heat, the polymer structure of the membrane opens and allows excess moisture to escape to the outside air. The product has won the Avantex Award 2007.
- Sympatex High2Out is a two and three layered system of membranes including an additional absorbent layer. Yet another product is Sympatex Reflexion, which includes an aluminium covered membrane. An additional padding isn’t necessary. Flexible and specially tailored to any activity level, Sympatex Phaseable works in harmony with the body’s natural temperature regulation – thanks to its smart climate management attributes. At low activity levels, the body is protected by an insulating layer of air. As the exertion level increases, the membrane expands – thus removing the insulation that is no longer needed. At the same time, this expansion increases breathability. Another decisive advantage: Sympatex Phaseable is a 2.5-layer laminate – a perfect combination of the lightness of a 2-layer laminate with the durability of a 3-layer laminate.
The so-called soft shells combine membranes with fleece and/or woven fabrics. So the garment manufacturer will only have to handle one fabric instead of two or more, as usual for the so-called hard shells made up from outer fabric, interlining or wadding and lining. Malden Mills say that in 90 percent of the applications, a soft shell will do the job even in bad weather conditions. In only 10 percent of the situations, a hard shell will be the best solution. A very successful trademark is Windstopper, a product of W.L.Gore & Associates.
Classic membranes have a strong market position
Thanks to the long history of water and wind proof membranes, they have a good market position. The most famous brands are Gore-Tex and Sympatex; many similar products followed in the wake, but never reached their popularity and branding position.
Although W.L.Gore, a pioneer in functional membranes, does not publish detailed figures on sales or market share, Mr Hans-Peter Rudolph, communication manager of W.L.Gore Germany, says: “Gore products have the highest turnover growth in the trade today.” The reasons for this success, Rudolph continues, are the numerous new products of the last years and the recently launched communication concept for the brand Gore-Tex. The communication would focus on features like water and wind proof as well as on breathability. The investment to push the brand will be about 80m Euro within the next three years.
This makes clear that the market for membranes is tough. Technical features must be proven. Testing under rough conditions in laboratories and in real life (marketing-wise with renowned protagonist wearers) is common.
Clever: Phase Change Materials
[bleft]Flexible and specially tailored to any activity level, Sympatex Phaseable works in harmony with the body’s natural temperature regulation – thanks to its smart climate management attributes.[/bleft]
The hottest phase of introduction of Phase Change Materials (PCM) was in the 1990s. Originally the PCM technology was developed for NASA and helped astronauts to stand the extreme temperature fluctuations in space. Outlast Technologies, Inc., a privately held U.S. corporation, claims: “From time to time products appear on the market claiming a reference to NASA, but most are without authorization. ‘Official clearance’ is provided by the US based Space Foundation (a non-profit organization linked to NASA). In May 2003, this officially recognised organization awarded Outlast the prestigious seal of approval ‘Certified Space Technology’. Worldwide, there are today only 34 companies that have received this award; Outlast Adaptive Comfort is the only textile application.”
Today, the technology applying microPCMs (about 3m capsules per cm²) to fabrics is settled and the market has calmed down. The microcapsules are added to fabrics by a conventional pad-dry-cure process or incorporated in acrylic fibres. Newly developed cellulosic fibres joined the market only recently.
Adding microPCMs to cellulosic fibres is a project of the TITV institute/Germany and the fibre company Alceru/Germany. The first fibres with incorporated microPCMs have been launched in the market under the name Smartcell Clima Fibre by Alceru.
Outlast Europe, based in Heidenheim/Germany, and Kelheim Fibres, Kelheim/Germany, set up viscose fibres with incorporated PCM. This fibre can be blended with any fibre from cotton, polyester and polyamide to technical fibres such as aramid. Mr Pat GRUBER, CEO of Outlast Technologies, sees markets beyond the heavy duty market: “Our new Outlast viscose fibre allows us to apply the benefits of our technology to intimate apparel, knitwear, women’s wear such as dresses and even more mainstream products like shirts/blouses and pants. Our home furnishings offering will also be enhanced with the addition of Outlast viscose fibre for use in bedspreads, blankets, sheets and mattresses, etc.” Mrs Barbara Fendt, marketing manager at Outlast Europe, adds: “PCM is a great product for Best Agers. But it has to be strongly supported by communication, also at the point of sale.”
Early 2008, Marks & Spencer launched the first long-sleeve zip-up top, a short-sleeve crew-neck top and long pants (all cotton and viscose Outlast). In spring/summer 2008 the Outlast Climate Control concept with the practical added value should reach other product groups.
Among the suppliers of fabrics with PCM technology are Schoeller (Schoeller PCM), Plouquet/Germany (licensed by Outlast throughout Europe) and Freudenberg/Germany (Comfortemp, a product for bedding).
In India, The Arvind Mills Ltd., Ahmedabad, are exclusive partners of Outlast for the Indian market. Arvind offers Outlast products for shirts, denim, cotton trousers/Khakis and knitwear. They are also suppliers to Marks & Spencer.
W.L.Gore communication manager Hans-Peter Rudolph doesn’t consider PCM as competition to membranes as “these products do not offer any protection. Internal tests would have shown no significant advantage in using PCM,” he claims.
Design for function
Designing high-tech functional garments has a lot to do with analysis of the needs of the wearers, research of adequate and maybe new materials as well as the need for stylish appearance.
Body mapping is one of the most important actions of the designers: here they define the areas where cooling and warming is needed. Reins should be kept warm, the centre of back and chest as well as the arm pits need some cooling when the action makes the wearer sweat. Infrared photography allows detecting these areas and the effectiveness of the chosen textile and apparel design. The access to climate chambers is necessary.
An example is the Biber Performed Shirt produced by Trerè using seamless circular knitting technology. The parts where the sweating is important will be covered by specially designed structures, the patented 3D-Bionic Sphere-System. These bulky structures can absorb more liquid and moisture than just plain structures. More than that, they will form climate channels, in which the air can circulate and remove the moisture. The product received the Red Dot Award 2007.
Yet another approach is to patch different types of fabrics according to the function needed: more wadding in the rein area, PCM-fabrics on the chest front and back, airy fabric structures on the arm pits, just to name the main ones.
More than that, zippers and cleverly folded/unfolded pleats could be used for vents. Bands and variable press buttons or Velcro could help to regulate the openings. Special constructions could keep wind, rain or snow from entering the openings – when needed.
Wherever membranes must repel water, the seams must be safely glued, welded or taped.
A multitude of interesting and fashionable designs can be seen on fun snow sports and functional mountaineering apparel. That’s the ‘cool’ way of keeping warm.