Hiking Clothing Tips
In this section we deal with modern design in outdoor clothing and with the latest types of fabrics available. Note in particular that cotton is not recommended for most types of outdoor wear, especially underwear and the mid layers. Cotton is not very warm and absorbs moisture too easily to be used for clothing that needs to stay dry and to insulate.
Types of Fabric and the layering system
The layering system in outdoor clothing is in principle divided into three components – namely: first, middle, and outer layer. The function of the first (base) layer is to mobilize moisture away from the skin; the middle layer (layers) is the warmth provider, and the final outer barrier safeguards against the elements, whilst still allowing the internal moisture build up to escape through it in vapour form.
Personal clothing that can “breath” is vital for comfort and warmth. Multiple layering is more effective thermally than one thick garment; adding or subtracting garments enables precise thermal comfort levels to be attained.
Currently synthetic fibres are manufactured with either hydrophobic or hydrophilic properties.
Polyester, polypropylene, chlorofibre, etc. have given rise to numerous brands which include: Polartec, Nordic, Quick-wick, Drynamix, Capilene, Dryflo, Rhovyl, Cool max, Wick dry, etc. Acrylic and cotton fibres should not be used as they saturate rapidly and take very long to dry. With the appropriate active performance wear there is no need for backup (spare) clothing in extreme conditions.
The first or base layers are often confusingly known as thermal winter clothing – however their primary purpose is to maintain a comfortable environment next to the skin, making it ideal for year-round use, including providing a greater protection from the sun when worn on it’s own during hot weather. Note these base garments can also take the form of T shirts and short pants made from moisture wicking materials.
Hydrophobic (water hating) fabrics rely on the heat provided by the body to mobilise the moisture away from the skin.
Hydrophilic (water loving) fabrics normally rely on dual density weaving; thicker filaments on the inside, and thinner on the outside – thus actively pulling water to the outside of the fabric where it can evaporate leaving you dry and comfortable.
Another fabric that also does an admirable job is silk, however it is more expensive than synthetics, and although silk thread has a very high tensile strength, it is very low on abrasion resistance, leading to extremely quick wearing out of the garment.
First Layer (base layer)
The first items to be considered should be underpants / long thermal underwear, close fitting shirts and bras as these items sit close to the skin and are the most important in the quest for warmth and comfort.
Fitting of base layers is largely a personal preference. Runners and cyclists may prefer a close fit for aerodynamic reasons. For Mountain walking activities the preference tends towards a more comfortable loose fit.
Basic factors to take into consideration: Choose well fitting base layers that do not chaff and are the correct size. Be aware of pressure areas where chafing may occur, such as the armpits. Also note that extremities such as hands, head, and feet should not be ignored and exactly the same process applies when it comes to design and fabric choice.
Second layer (mid layer)
The second layer is for warmth and various garments can be used either individually or in conjunction with each other. They are used to regulate body temperature, and provide optimum thermal comfort. Polyester based fabrics with moisture management capability are produced by various manufacturers – some of the better known names are: Polartec, Power Day, Power Stretch, Thermal Pro, Windbloc, Nordic, Entropy, and Gore Windstopper. (Be careful of cheap imitations, as they will not perform adequately when wet.) Fabrics are graded numerically as series 100, 150, 200, 250 and 300 – this simply refers to its mass in grams per square metre, the larger the number, the heavier and thicker the material. The greater the weight, the greater the warmth of the garment.
Mid layer(s) provide warmth by trapping air whilst still allowing moisture to wick away from the base layer, which stops condensation building up against the skin. Warm air is the best insulator, and one of the most efficient ways of trapping air is by utilizing open weave, or knit fabric like fleece. The body warms up the air particles within the fabric construction. If more warmth is required, additional thinner layers are preferable to one heavy layer.
The open weave of the fleece is vulnerable to the chilling effects of wind. Research shows that 0˚C at 15 m.p.h. will have the same effect on the body warmth as a drop in temperature to –15˚C. It is for this reason that a wind-proof shell is necessary for optimal results in windy conditions.
Today some thermal clothing is manufactured with a wind-proof membrane in the fabric. This can add greatly to the warmth of the garment. However, note at this point that wind resistant fleeces are pro rata less breathable, and potentially create greater heat build up next to the body, which may lead to overheating during high physical activities. They are also more expensive than ordinary polar fabrics.
Choice between the various grades depends on many factors, including the individual’s level of activity or inactivity, wind speed and season of the year.
Synthetic filled jackets (ie. Trevira, hollow fibres and micro fibres) have largely been replaced by fleece, but some manufacturers are still producing them, as they serve the same purpose as down jackets, with the advantage that they perform better than down under wet conditions, dry quicker and are cheaper. They unfortunately tend to be bulkier and heavier than down equipment.
Down jackets should preferably be kept to the outer perimeter of the layering system so as to be subjected the least to dampness from perspiration. N.B. Down is the most efficient insulator (warmth to weight ratio) available, and is by far the best choice for extreme cold.
For ultra cold conditions one of the midlayer jackets should be selected with dedicated features such as a front that does not have pockets in the lower area where a harness or rucksack hip belt will go. Make sure the pockets are big enough to keep spare gloves and sunglasses. Two pouch pockets in the interior are also very useful to keep drinking bottles from freezing, with the added bonus of quick and easy access.
The legs should have the identical system of protection as the torso, especially in severe cold. Useful features on fleece pants are: anti abrasion protection on the seat and knee areas; articulated knee construction; side zips to facilitate entry over boots and also useful for adjusting ventilation.
Third layer Outer layer (Shell)
The final layer provides frontline protection against wind, rain, sleet, and snow, while allowing the mid layers to operate effectively.
The first thing to consider when choosing shell garments is fabric.
There are three choices: waterproof, water-resistant/breathable, and waterproof/breathable.
Waterproof fabrics keep water out, but keep sweat in; they are however inexpensive.
Water-resistant/breathable fabrics allow perspiration to escape but barely repel the lightest drizzle, useful for high-intensity aerobic work in a relatively dry environment (e.g. cold and windy).
Waterproof/breathable fabric is the logical choice for the rigours of mountain walking, since it repels water from the exterior and releases perspiration from the interior. In reality waterproof/breathable fabrics do have limits, as none of them will “breathe” fast enough to dissipate all the vapour build up during periods of heavy exertion.
An increasing numbers of manufacturers are producing waterproof/breathable fabrics. These work by one of two principles, namely membrane design or coating design incorporated in a layer in the garments fabric.
The basic layer profile of waterproof/breathable shell construction consists of incorporating a thin membrane sandwiched between a face fabric (abrasive resistant and dry treated) and a liner fabric (with wicking capability) bonded together – this is a three-ply construction. A more economical two-ply, omits the inner protective layer, but uses a loose hanging mesh liner instead.
Goretex is the originator of the membrane concept that has become the benchmark by which all competitors are judged. On the other hand “triple point ceramic”, is regarded as one of the most efficient performers of the coating method. Other products are Hydry-logic, Helly-tech, Hyvent, Conduit, Aquafoil, Ventex, Weathertite, K-tech, Climatex, Driaqua, Drywall, Drilite and Aquadry.
The way the membrane laminate process works is known as “mechanical”, and the coating as “chemical” – the operational difference being in that pores of a membrane are 20 000 times smaller than a droplet of water, but 700 times larger than a molecule of water vapour. On the other hand the coating method impregnates the fabric with either a micro porous or a hydrophilic coating. Micro porous works on a similar principle to the microscopic pores of the membrane, whereas the hydrophilic process is activated by the heat generated internally. Relying on the natural properties and chemistry of moisture vapour, the pressure that accumulates within the fabric, forces the vapour along polymer chains of the coating to the exterior of the fabric.
Features of a shell should include, a storm flap over zip areas (more expensive models use waterproof zips), draw cords at hem, waist, and hood with elasticised flexibility, seams and embroidery must be taped to prevent seepage, vents via pit zips or pockets with mesh liners, Velcro adjustable cuffs and reinforcement pads in areas of high abrasions. The hood should provide enough volume if wearing a helmet and be adjustable for peripheral vision.
A shell should be able to accommodate all the relevant mid layers. When arms are lifted, a good design with articulated elbows and armpits allows greater freedom of movement; if in doubt, rather choose larger than too small.
Protection for the lower extremities relies on pants or bibs.
Bibs provide chest and lower back protection. Pants having a lower cut are not as apt at keeping snow out and offer less pocket space. Knee and seat should be reinforced; also knee articulation is a plus factor.
Full side zips simplify placement and removal, with the added bonus of being able to ventilate the legs under high exertion. A “Rainbow” or full crotch zip must be compatible with the opening apertures of the inner layers to simplify “the taking care of business”!
Regular and careful cleaning maintains the performance of the outer shell, abrasions and scuffing removes the outer repellent coating on the face side of the fabric. A saturated surface impedes the vaporisation process; this is resolved by treating with durable waterproof repellent (DWR). Make sure compatible products such as Nikwax.
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