Collins Complete Hiking and Camping Manual: The essential guide to comfortable walking, cooking and sleeping

Heat leaves your body in the following ways:

Conductive Heat Loss occurs when contact is made between your body and a cooler surface. It can be minimized by not sitting on the cold ground, especially on snow. Conduction occurs 25 times faster with wet clothing than with dry. Prevention: Thickness of insulation.

Convective Heat Loss occurs when your body heat warms the air adjacent to your body; that air then rises and moves away from your body and fresh colder air replaces it. Wind increases the speed of heat loss through convection. The impact of heat loss from convection is measured by the windchill factor. (See “Windchill Index (#litres_trial_promo),”.) This same process happens when you are submerged in cold water, but it happens much faster than in air because of the greater density of water. An important element in dressing for the outdoors is trapping the air around the body. Prevention: Windproof garments.

Radiant Heat Loss is caused by the escape of infrared radiation from the body. It is minimized by wearing insulative fabrics or those with reflective fabric that reflects the heat back to the body. Prevention: Thick layers of insulation or reflective material.

Evaporative Heat Loss occurs when perspiration (water) on the skin evaporates, drawing heat from the body. Changing water from a liquid to a gas takes a lot of energy. This is why sweating helps cool you off when you are hot. In hot weather, evaporation is essential in cooling your body down to prevent heat illnesses. (See “Heat Challenge (#litres_trial_promo),”.) However, when it’s cold you want to minimize the amount of sweating to reduce evaporative heat loss. Prevention: Fabrics that move water away from the skin and vapor barriers (page (#ulink_97b24959-fc97-5254-86a9-926c10c65652)).

Trapping Your Body Heat

Clothing insulates you from the environment by trapping your body heat. The best insulation is a layer of static, unmoving air close to your body, known as “dead air.” This air is warmed by heat given off by your body (through radiation, conduction, and convection) and maintains a warm microclimate around your body. Clothing insulates by creating pockets of dead air. How much a particular clothing fabric insulates is based on its loft or thickness—the greater the loft, the more dead air space. Also, different fibers are better at creating dead air space than others. The goal is to find a fiber that creates lots of dead air space and at the same time doesn’t weigh very much. This is known as the warmth-to-weight ratio. A really light fiber like down has an excellent warmth-to-weight ratio.

Not all clothing is designed to insulate. In hot desert environments, thin layers of clothing with negligible loft are worn not to insulate but to provide shade from the sun to minimize overheating. You want something loose-fitting that ventilates and allows your sweat to evaporate, cooling you off.

THE LAYERING PRINCIPLE (#ulink_026d7d1f-fd9e-5926-bf18-66dc594979f5)

By wearing multiple layers of different types of fabrics you can maintain a comfortable body temperature without excessive sweating (which can lead to heat loss). Throughout the day, you “layer up” or “layer down” as temperature conditions and/or activity levels change. By experimentation, you can determine which of the base layer, insulating layer, and shell layers you require in various situations. The layers should not restrict your movement and the outer layer, especially, should not be too tight, since tight outer layers squeeze the layers beneath and actually compress the dead air space in layers below, reducing their insulation value. You can modify one or all of the following factors to properly thermoregulate.

Clothing Layers The number and type of layers you wear allow you to create sufficient dead air space for insulation and protection from external conditions (wind, rain, etc.). Extra layers may be added in the cooler hours of the morning or evening, or when your activity level drops, like at a lunch break.

Activity Level Increasing or decreasing your activity level increases or decreases the heat you generate.

Staying Dry An important factor in retaining heat is to minimize wetness, since you can lose heat 25 times faster in wet clothing than in dry. Moisture comes internally from perspiration generated by exercise or externally from rain or snow. You want clothing layers that minimize the buildup of moisture close to your skin and also protect you from external moisture.

Ventilation Opening up or closing the layers of your clothing allows you to decrease or increase heat loss as needed, without having to actually remove or add a layer. As you move, a bellows action occurs in clothing that pumps your accumulated warm air out through openings and pulls the cooler air in. In some conditions, this bellows action can reduce your body’s insulation by 50 percent or more, so unzip if you are too hot and zip up if you are cold. Ventilating also prevents moisture buildup from perspiration. Look for clothing that allows for easy ventilation, such as full-zip outer shell jackets, armpit zippers in shell jackets, zip-front turtle-necks, button-down shirts, and side-zip pants. Rolling up sleeves and pants legs is another way to ventilate.

THE CLOTHING LAYERS (#ulink_67d8a2af-b31a-5112-add5-b92b65688584)

The Base/Wicking Layer

The base/wicking layer keeps the skin dry and comfortable. This layer transports moisture from body perspiration away from the skin to the outside of the fabric. This layer should dry quickly. In cool weather, wear close-fitting layers to provide insulation. In warm weather, wear loose-fitting layers to maximize ventilation and absorption of moisture for the skin to keep cool and dry. There are a number of different ways to wick moisture away from your body:

Hydrophobic/Hydrophilic Fibers These are synthetic fibers often made of polyester or polypropylene that do not absorb water (as cotton does). They are extremely effective worn directly against the skin to keep it dry and reduce evaporative heat loss. In addition to not absorbing water, many of these fabrics are hydrophobic (“water-hating”) on the inside, so they push the water vapor from the area of highest concentration (next to your skin) to the outside of the fabric. Some fabrics are hydrophilic (“water-loving”) on the outside and pull the water outward. Others are bicomponent and use both a hydrophobic inner layer and a hydrophilic outer layer. The hydrophobic or hydrophilic nature is accomplished either by the physical characteristic of the fabric itself or by applying a chemical coating to the fabric. Examples: Capilene, Lifa, and Dryline.

Micro-channel Fibers These are synthetic fibers with tiny channels or capillaries within the individual fabric threads. These fabrics rely on what is known as “capillary action” to transport moisture through the channels from next to your skin to the outside of the fabric. Some fabrics are bicomponent with an inner layer of macrofiber yarn and an outer layer of microfiber yarn. The outer layer has a much greater surface area, which helps “pull” the water to the outside of the fabric. Examples: CoolMax and Polartec PowerDry.

Some of these fabrics have a definite “inside” and “outside.” If you wear a bicomponent garment inside out, you defeat the purpose of the garment. Garments that rely on the physical characteristics of the fabric itself rather than a chemical coating continue to function regardless of the number of times they are washed, while those that rely on a chemical treatment may eventually “wear out.” There are different thicknesses of these fabrics, generically called lightweight, medium weight, and heavy or expedition weight. The thicker fabrics offer great insulative value along with their wicking properties. Pro: Excellent inner layer. Minimizes moisture next to the body, where high conductive heat loss can occur. Con: Not windproof, so best used as an inner layer. Some fabrics retain odor more than others.

The Insulating Layers

The main purpose of the insulating layer is to create dead air space for insulation. It also absorbs some of the wicking layer’s moisture, keeping the moisture away from your skin, so you want it to easily pass moisture. Depending on the temperature this can be one layer or many layers.

First Layer Your first insulating layer is typically shirts and pants. This could be an extension of the wicking layer—for example, wearing middle-weight to expedition-weight polypropylene that both wicks and provides insulation. Layers that allow you to “open” and “close,” like zip-front turtlenecks or button-down shirts, allow for ventilation during periods of high heat-producing activity. Synthetics like polypropylene or Thermax work well in this layer.

Second Layer If you need more loft for insulation, add another insulating layer like synthetic fleece or wool pullovers, sweaters, jackets, and pants.

Outer Layer If it is really cold, you may need to add an even thicker layer like an insulated parka or pants. These typically have an outer and inner layer of fabric and either down or some synthetic insulating fill sandwiched in between. These layers are often worn at the beginning and end of the day in camp, when activity levels are low or in temperatures below freezing.

The Insulating Materials

Fleece is a synthetic fabric often made of a plastic (polyester, polyolefin, polypropylene). It has a “fuzzy” 3-D quality that imitates a sheep’s fleece and gives it insulating properties. It remains warm when wet, does not absorb moisture, and dries very quickly. This material has an insulative capacity similar to that of wool. Fleece is manufactured in a variety of thicknesses, offering different amounts of loft and insulation and numerous layering possibilities. Some fleece garments are made from recycled plastics or with a middle wind-proof layer. Pro: Fleece is able to provide the equivalent warmth of wool at half the weight. Con: Fleece by itself has poor wind resistance and almost always requires an additional wind-resistant layer. Examples: Polartec 100, Polartec 200.

TRICKS OF THE TRAIL

Loose fill versus continuous fill Insulating fibers can either be loose fill, like down, or continuous fill, like Polarguard. Loose fills are made up of small individual fibers. In order to keep the fibers equally distributed throughout the sleeping bag or garment, the manufacturer has to sew in interior “walls” of fabric known as baffles to create individual compartments to hold the fill. This adds a lot to the manufacturing cost.

Continuous-fill fibers are made in large sheets that can be cut into the right shape and sewn directly into the sleeping bag or garment without baffles.

Wool derives its insulating quality from the elastic, three-dimensional wavy crimp in the fiber that traps air. Depending on the texture and thickness of the fabric, as much as 80 percent of wool cloth can be air. Wool can absorb a fair amount of moisture without imparting a damp feeling because the water “disappears” into the fiber spaces. Even with water in the fabric, wool retains some dead air space and will still insulate you. The disadvantage to wool is that it can absorb a lot of water, making it very heavy when wet. Maximum absorption can be as much as one-third the garment weight. Wool releases moisture slowly, with minimum chilling effect. Pro: Tightly woven wool is quite wind resistant. Wool clothing can often be purchased cheaply. Con: Wool garments can be heavy, take a long time to dry, and can be itchy against the skin. Some people are allergic.

Down The very soft underbody plumage of geese or ducks provides excellent insulation and dead air space for very little weight. (Goose down is finer quality than duck.) Down is rated by its fill power, or how many cubic inches of volume an ounce of down will fill. Fill power goes from 550 cubic inches up to 800—a 700-fill sleeping bag lofts better and is more thermally efficient than a 550-fill bag. Most high-end sleeping bags are made of 700 fill; 800 fill is mostly for expedition-quality garments and sleeping bags.

Since down is a loose fill, sleeping bags and clothing must have a series of small compartments sewn in with baffles to hold the fill evenly throughout, which adds to the manufacturing cost. Down is useful in sleeping bags since it tends to conform to the shape of the occupant and minimizes convection areas. It is also very compressible, which is an advantage when packing. But the same compressibility means that your body weight compresses the down beneath you, significantly reducing your insulation from the cold ground, so you need an insulating pad underneath you more so than with a synthetic bag. Pro: Excellent insulator. Incredible warmth-to-weight ratio. Compresses to extremely compact size. Long life span if cared for properly (up to 20 years). Con: When down gets wet it simply clumps together and loses almost all of its insulative value and is almost impossible to dry in the field. Use depends on your ability to keep it dry. When using a down sleeping bag, take special care to prevent it from getting wet. For example, a vapor barrier sleeping bag liner in a down bag will help the bag stay dry from the inside and a waterproof-breathable bivy sack will help the outside keep dry. Keeping the bag in a waterproof stuff sack will protect it during the day. In wet conditions a down-fill outer parka may get soaked, and a synthetic-fill would be better. Down is a loose fiber fill that requires baffles (see “Tricks of the Trail,” (#ulink_4e259739-1d37-5fe6-95cf-f41f1e4f9aa6).) Expensive. Some people are allergic.

Synthetic Fibers There is a multitude of different synthetic fibers used for garment and sleeping bag fills. Most are based on some form of polyester. These are primarily used in sleeping bags and heavy outer garments, like parkas. The fibers are fairly efficient at providing dead air space (though not nearly as efficient as down). Some products like Polarguard are made in large sheets. Others create additional dead air space by having hollow channels within the fiber (e.g., Quallofil). Pro: They do not absorb water and dry fairly quickly. Some fibers are produced in sheets that do not require baffling. Con: Heavy. Not as efficient an insulator as down. Hard to compress to a small size. Some are loose fibers that require baffling. Fibers produced in sheets tend to break down over time, losing their loft more quickly. Examples: Polarguard 3D, Polarguard Delta, Quallofil.

“Superthin” Fibers These synthetic fibers are based on the principle that by making the fiber thinner you can increase the amount of dead air space around the fiber. Some superthin fibers are close to the weight of down for an equivalent fiber volume. They stuff down to a small size and have similar warmth-to-weight ratios as down without the wetness issue. Pro: Lightweight and thermally efficient. Good compressibility for stuffing. They do not absorb water and dry fairly quickly. Some fibers are produced in sheets that do not require baffling. Can be stuffed down to a small size. Con: Some are loose fibers that require baffling. Some superthin fibers like Thinsulate are heavy and therefore aren’t good insulators for larger items like parkas and sleeping bags but are very effective in smaller items such as gloves and boots. Examples: Primaloft, Lite Loft, Thinsulate.

Phase Change Materials These materials use tiny spheres or microcapsules either laminated to or embedded within the fabric surface. What is unique about this approach is that the microcapsules can be manufactured to absorb or release heat at a specific temperature. In products designed for cold weather, the microcapsules absorb and retain body heat during periods of activity, and then release the heat back during periods of inactivity—sort of like taking off a layer and putting one back on. For clothing designed for warmer temperatures, the microcapsules absorb body heat, providing a cooling effect. Currently used mostly in gloves and boots. Pro: Absorbs heat to keep you cool in high activity. Releases heat back in low activity. Con: Expensive. Fabric is “tuned” to either cold temperatures or warm temperatures. Example: Outlast.

The Shell Layers

The shell layer consists of an outer jacket and pants layer that protects from wind, rain, snow, and sun. It is essential to have an outer layer that is wind-proof and at least water resistant, if not waterproof. Acting as a windbreaker, the shell layer minimizes convective heat loss, containing the warmth trapped by layers beneath. If your shell layer is waterproof but not breathable, moisture buildup from perspiration is possible, so look for garments that provide ample ventilation options, such as full-front zips and armpit zippers. Waterproof/breathable fabrics provide both wind and rain protection and still allow some perspiration moisture to escape. However, in a driving rain, there is almost nothing you can do to stay totally dry when you are being active. You will either zip up and get moist from sweat or ventilate and get wet from rain, so the goal is to minimize moisture. One thing to think about with shells is sizing—something that fits snugly over a shirt or blouse in the store is not going to work over your wicking layer and two insulating layers. In those cases you need a garment cut large enough to handle most of your inner layers. At the same time, it is not likely that you would buy something so big that you can fit your shell over a down or synthetic parka, so you need to ask yourself if the outer parka also needs to be waterproof.

Wind Shell A wind shell is just that—a shell that projects you from the wind. It is breathable, lets moisture out, and keeps wind out. Typically these are made from fairly lightweight materials such as nylon or nylon blends. They are tightly woven so there are no open spaces for the wind to penetrate. They dry quickly and make excellent outer shells for being active in dry conditions. Pro: Windproof. Allows body moisture to escape. Lightweight. Inexpensive. Con: Not waterproof. Examples: Ripstop Nylon, Pertex.

Soft Shell Soft shells are a step up from a wind shell. These are wind-resistant and water-resistant shells. They are made of synthetic materials with an open weave that allows body heat and built-up moisture from inner layers to escape but is still tightly woven enough to repel light wind and rain. They perform best in active sports where heat production from activity helps draw the moisture out. The heat transfer also works to keep precipitation from entering the fabric. These will keep you dry in “gentle rain” but are not designed to be completely waterproof. They dry quickly and make excellent outer shells. Pro: Wind resistant. Water resistant. Allows body heat and moisture to escape. Lightweight. Dries quickly from body heat. Con: Not completely windproof. Not waterproof. Expensive. If the garment gets totally wet and is in contact with wet inner layers, you can quickly chill from fast water-driven conduction. Examples: Conduit Soft Shell, Polartec Power Shield, Schoeller Dryskin.

Hard Shell Hard shells are waterproof and are designed to keep you dry in pouring rain conditions. There are two approaches to hard shells:

Waterproof Shell These are fabrics that use some type of impermeable waterproof coating (i.e., coated nylon). These will keep you dry from rain but allow water vapor from perspiration to build up in layers underneath. Pro: Very waterproof. Windproof. Inexpensive. Con: Allows for significant body moisture buildup.

Waterproof and Breathable Shell There are a number of ways to make a waterproof and breathable outer shell. All rely on the principle that water droplets from rain are more than 20,000 times larger than water vapor. With a fabric that has a layer with very tiny pores, water vapor can pass through from the inside to the outside while the outside remains impenetrable to water droplets. With all of these fabrics there is always a trade-off between the degree of waterproofness of the fabric and its breathability. Some fabrics use a microporous membrane that is laminated to the fabric (Gore-Tex, Sympatex); others have a microporous coating on the fabric (Ultrex, Triple Point Ceramic, Entrant). Pro: Degrees of waterproofness. Degrees of breathability. Windproof. Con: Degrees of waterproofness. Degrees of breathability. Some body moisture buildup. Expensive.

All hard shells require some form of seam sealing. While the fabric itself may be waterproof, any place where there is stitching means a hole going through the fabric that can let water in. There are a number of approaches to seam sealing including glue, heat sealing, and seam tape.

TRICKS OF THE TRAIL

Bringing Your Rain Gear Back to Life After frequent use, all waterproof and breathable fabrics start to lose their edge. You can revitalize them by washing with a mild nondetergent soap, machine drying, and then lightly ironing the outer fabric on a medium temperature setting. The washing helps restore the membrane or coating’s effectiveness, and the heat of the iron helps bring back the ability to resist water.

Many fabrics (waterproof and waterproof/breathable) have a DWR (durable water repellant) chemical coating on the outside of the fabric. This is what makes water bead up on the surface of your jacket. It’s like your car after a new coat of wax. Over time these coatings wear off, allowing water to seep into the fabric. The garment may still be waterproof, just soaked on the outside and heavier. You can revitalize your DWR finish with spray-on products or by machine-washing it back in with a liquid treatment.

The Head Layer

This is for sun and rain protection, and to reduce heat loss. Up to 70 percent of the body’s heat can be lost through radiation and convection at the head in cold weather. Wearing a hat (preferably wool or synthetic) will conserve heat, allowing the body to send more blood to cold peripheral areas (hands, toes, feet). Other items like wide-brimmed hats can help in a downpour, keep sun off your face, and provide shade to help prevent overheating.

The Hand Layer(s)