Layered clothing

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Layered clothing means dividing clothes to layers that are worn on top of each other. Each layer has different, largely non-overlapping functions. Using more or fewer layers, or replacing one layer but not others allows for flexible clothing to match needs of each situation. Two thin layers can be warmer yet lighter than one thick layer, because the air trapped between layers is a good insulator. Layered clothing is particularly relevant in cold climates, where clothing must at the same time transfer moisture, provide warmth, and protect from wind and rain.

Outdoor and sports wear manufacturers favor layered clothing because, among other reasons, it allows them to offer so called "technical" or "functional" clothes which are optimized for the particular demands of a specific layer. Such clothes are often made of advanced synthetic materials, and can be expensive.

1 Layers
2 See also
3 External links

[edit] Layers

Usually at least three layers are identified as following.

Inner layer provides comfort by keeping the skin dry. Also called base layer or active layer.

Mid layer provides warmth. Also called insulating layer.

Shell layer protects from wind and water. Also called outer layer.

Often clothes combine two adjacent layers, for instance in case of warm undergarments that provide both comfort and insulation.

[edit] Inner Layer

The purpose of the inner layer is to draw the sweat away from the skin to the next layers, which makes the wearer feel warmer and more comfortable. The transfer of moisture happens due to capillary action. This is sometimes called wicking, and thus the used materials wicking materials. When moisture has moved from the skin into (nonabsorbent) clothing, it has more surface area and will evaporate faster.

Synthetic materials such as polyester or microfiber-based fabrics are good choices as they don't absorb moisture but may transfer it well. Downsides are that they can be expensive or feel uncomfortable against skin.

Silk feels more comfortable, but is weaker and harder to take care of, and is less commonly used.

Cotton is cheap and feels comfortable when dry but it absorbs moisture easily and is slow to dry out (especially in cold conditions). So cotton and denim are not a good choice if sweating and cold or rain is anticipated. Cotton is still a great choice for hot, dry climates where drying is not a problem. It will feel cool and provide sunscreening (but should not be relied upon for this unless it is thick cotton)

[edit] Mid Layer

The mid layer is needed in cold weather to provide additional insulation. For maximum warmth multiple thin mid layers can work better than one thicker. The mid layer should be more loose fitting than the inner layer, as this leaves insulating air between the layers. However if best possible moisture transfer is desired, there shouldn't be a too great gap between any adjacent layers of clothing, as that'll reduce the capillary action based moisture transfer from one piece of clothing to another.

Wool is the traditional mid layer material with several good properties: good insulation even when wet, nonabsorbent, transfers moisture.

Fleece has features of wool, but is lighter. Fleece garments traditionally come in different thickness (micro, 100, 200, 300 - with 300 being thickest and least flexible)

Down make garments which are very warm, light and can be packed down (squeezed) to take up very little room in a rucksack. They offer the best warmth:weight ratio of any material. For this reason down jackets and body-warmers (and sleeping bags) are popular with hill walkers and mountaineers more as garments to pull on when they are stationary and in the evenings/night. Down is also expensive and makes for a thick garment which loses most of its insulating properties when wet (from sweat or rain). Washing down garments removes some of the oils from the feathers and means that they do not fluff up as well (referred to as "lofting") when they dry out. Continual washing results in garment loosing its ability to loft (fluff back up) and so looses its insulation properties. Wool and fleece do not suffer from these problems and so are more popular as a mid-layer. They continue to loft after washes, they continue to insulate and wick when wet from sweating or rain and then dry quickly. This makes them the choice of layer for sports that produce sweat or where a down garment cannot be protected from the rain. Most manufacturers offer a synthetic version of their down garments and sleeping bags. These try to simulate the warmth to weight ratio of down but better tolerate wet and washing.

Cotton, as with the inner layer, is a cheap alternative, but a reasonable choice only when low insulation and moisture transfer is needed.

[edit] Shell Layer

The outermost clothes are called the shell layer but only if they block wind and/or water. If wearing, for example, just an undershirt (inner layer) and a fleece jacket (mid layer), there is no shell layer. Ideally the shell layer lets moisture through to the outside (that is, is breathable), while not letting wind and water pass through from the outside to the inside. While this is enabled to some degree by modern materials, even the best and most expensive materials involve a trade off between breathability and water/wind resistance. The shell layer clothes may also need to have good mechanical strength.

Plastic raincoats protect completely from water and wind, but let through no moisture. To compensate for that, such raincoats usually have flap-covered holes and are very loose fitting at the bottom so as to allow air circulation.

Waterproof breathable materials are waterproof and somewhat breathable. Their essential element is a thin, porous membrane that blocks liquid water, but lets through water vapor (evaporated sweat). The more expensive materials are typically more breathable. The best-known brand is Gore-Tex.

Water resistant materials block water only partially. On the other hand they are usually more breathable and comfortable, thinner, and cheaper than completely waterproof materials. Water repellent coatings are often used. Garments of this category are sometimes called soft shell, in contrast to waterproof garments that are called hard shell. The classic soft shell clothing system is Pile and Pertex which combines inner and outer layers – the Polyester pile inner wicks moisture away from the skin to the windproof Pertex outer where it spreads out and evaporates.

Feather and Fur Technology offers another type of soft shell system which is also an unconventional waterproof. They also advise the use of an OverShell layer or Shelter, which can add insulation over the waterproof when you stop exercising.

Softshell jackets are gaining in popularity for the following reasons: Hardshell jackets are "noisey": the fabric creates noise as the arms rub the body, and the garment flaps in the wind. Hardshell jackets have longer, roomier, less active styling (desireable in a waterproof over-layer but not if you are using your hands a lot or looking around) The market-leading breathable fabrics still only manage to allow around 25% of your sweat to escape (this figure changes depending on how easily someone sweats and how hard they are exercising) And so, there will always be sweat condensing within your garment layers. The breathability of these fabrics requires the moisture to evaporate from the outside of the jacket. If the air temperature is cold and the outside of the jacket is wet from rain, then even less moisture will be drawn through fabric. High water- and wind-proofness is rarely required for many active sports where the challenge for the garment wearer is to continually loose enough heat and sweat to stay comfortable. Softshell manufacturers suggest that their jackets will protect you in light rain or showers but you will need a waterproof jacket when the rain gets heavy or you slow down. There are an increasing number of new, specialised softshell fabrics coming on the market, each with different features and amounts of wind and water resistance, breathability, stretch, weight:volume. e.g. Scholler, Windstopper, Event.