All About Clothing Layering Systems

The Layering Concept

The concept of layering is known to provide both comfort and protection for those who spend time in the outdoors. With just three basic elements, an outdoorsperson can maintain total comfort in most any temperature or weather situation, and use the correct clothing combination based on the level of physical exertion.

1. Next to skin layer - Most importantly, this layer is non-cotton. It should also fit tightly, for the best wicking effect.
2. Insulative Layer - This layer provides warmth and should also be the most variable, because different activities/temperatures may demand more or less insulation.
3. Element Layer - Wind and water rob the body of warmth, therefore, choosing garments that are both wind and waterproof will benefit the user most.

The importance of a non-cotton base layer cannot be stressed enough, as many a ski-patroller will tell you that the hypothermia uniform is jeans and a T-shirt. Cotton absorbs water readily and takes forever to dry, making it dangerous to use as a base layer because it can actually accelerate the body's heat loss. Synthetic long underwear is both easy to obtain and comfort enhancing due to its ability to wick, or pull moisture away from the skin. Also, most synthetic fibers are very quick to dry, often the heat created by a person's body is enough to dry them out completely.

Insulative layers can take on many forms, and usually more than one is required, depending on the activity and environment. This layer is designed to trap dead air space so that a cushion of warm air surrounds the body. Low exertion and very cold weather may call for a bulky down or synthetic filled garment, while high exertion and very cold weather may be dealt with by using one or more layers of fleece or wool. It is extremely important not to overheat, as this will increase the amount of moisture vapor that leaves your body. A body at rest obviously requires more insulation than an active body at the same temperature.

The Element layer prevents heat loss. There are three ways a body can lose heat. Convective heat loss occurs when wind takes away the thin layer of body temperature air around us, forcing the body to expend precious energy to re-warm this lost air. Conductive heat loss occurs when contact between the body and any object cooler that itself exists. This can be the rock you are sitting on or wet clothing, the main reason why cotton is so dangerous. Lastly, evaporative heat loss occurs when anything we are wearing is in the process of drying out. This last type of heat loss can actually be very beneficial on a hot day, people who dip their hat in the river or lake and put it back on are experiencing evaporative heat loss firsthand. The element layer is so vital because it can stop the process of all three types of heat loss, sometimes making the difference between life and death.

1. The next to skin layer is perhaps the most important layer because is almost always hydrophillic or water loving. This keeps the skin dry, vital for comfort in all conditions. No outdoor clothing system should be without this vital element, as this is the foundation that will determine the comfort and safety of the individual, especially in inclement weather. Capilene polyester by Patagonia, Drylete polyester by Hind, and polypropylene are all effective at wicking moisture away from the skin, this is our first priority.
   
2. The insulative layer or can consist of wool, polyester fleece, down, or synthetic insulation materials, exactly like those found in sleeping bags. With the advent of modern fleece garments, wool has lost some of its popularity. It is possible to gather enough fleece garments to cover every portion of exposed skin on the body, making fleece an excellent choice for any variety of conditions. Fleece is lightweight, easy to care for, sometimes recycled, and extremely soft and cozy. Wool is still used as an insulative layer, but the itch that goes along with certain woollens makes most people opt for fleece. Some fleece is actually windproof, the result of sandwiching an impermeable laminate between the inner and outer layers of the garment. This type is a weight and space saver because two garments, a windbreaker and insulator are combined. The lightest, most compressible insulation material known to man is down, nothing synthetic or natural has even come close to the warmth to weight ratio that down offers. The only drawbacks to down insulated garments are the initial expense and the risk of water saturation. Water will render a down garment worthless as far as warmth is concerned, but the item must be completely saturated to be in this condition. For extreme cold weather activities when time is spent waiting or sitting motionless, down is an excellent choice. However, for the fair weather backpacker or day hiker, most down garments are simply too warm. Synthetic filled garments are capable of providing warmth to the user even in wet or humid conditions, because the synthetic fibers do not absorb very much water. In fact, a saturated synthetic filled garment can be wrung out and worn until dry while still providing warmth, making it a good choice when travelling to rainy locales. When choosing insulative layers, try to match the insulator to the activity, keeping in mind that two thinner garments offer more flexibility and comfort range versatility than one thick, bulky one. Also be sure to keep rain and or wind gear easily accessible so that these vital components of the layering system stay dry.
   
3. The third and final element layer is vital to keep the rest of the clothing system functioning properly, wind and water are the enemies in this case. Many unfortunate adventurers might still be alive today if they had taken the time to select and pack along adequate wind and waterproof gear. One thing to keep in mind is that it is much better to have a waterproof layer than just a windproof one, because any garment that is waterproof is also inherently windproof. A great variety of final layers exists, and sometimes cosulting with a trained, knowledgable salesperson is the best way to narrow the choice down to garments that will perform adequately for the activities which will be pursued most often. For example, a backpacker in Costa Rica will definitely want a different final layer than a mountaineer in Alaska. Certain coatings and laminates do have limitations and often a simple, coated nylon shell is the perfect balance of price, function, durability, and weight. Often, the expense of waterproof/breathable clothing is a limiting factor, but many non-breathable waterproof jackets have features that enable them to breathe "mechanically," even if the material itself is not. This type of feature can be as simple as an underarm zipper that allows hot air to escape, or a mesh-lined chest pocket that allows fresh air to enter the jacket as the user moves about. Also flaps that cover mesh panels are effective in creating the "chimney effect," pumping out hot air and pulling in cooler outside air. Whatever your choice for the third and final key points should be considered. First, make sure the item is sized large enough to accomodate any and all underlayers. Second, waterproof/breathable parkas are necessary for those who engage in aerobic pursuits, so do not plan on being both active and comfortable while wearing a non-breathable waterproof jacket unless it has some type of mechanical ventilation features. Last, it may be of more importance to make the investment in a Gore-Tex or other waterproof/breathable jacket or parka than a pant or bib because the torso area of a person's body undoubtedly needs the ability to breathe more than the area below the waist.