Part 1 of this series covered some fundamental concepts that are critical to dressing for cold weather fly fishing. But before exploring clothing systems, it is critical to understand the materials that are used in most modern cold weather clothing systems.
- Merino Wool: Mother Nature knew what she was doing when she equipped the Merino sheep with the wool it wears. Compared to regular wool, Merino is excellent at regulating body temperature, especially when worn against the skin, providing warmth without overheating. It draws moisture (sweat) away from the skin, a phenomenon known as wicking. The fabric is slightly moisture repellent (keratin fibers are hydrophobic at one end and hydrophilic at the other), allowing the user to avoid the feeling of wetness. Like cotton, wool absorbs water (up to 1/3 its weight), but, unlike cotton, wool retains warmth when wet, helping wearers avoid hypothermia after strenuous activities or weather events. And like most wools, merino contains lanolin which has antibacterial properties. It’s also one of the softest types of wool available, due to finer fibers and smaller scales. Merino has an excellent warmth-to-weight ratio compared to other wools, in part because the smaller fibers have microscopic cortices of dead air, trapping body heat similar to the way a sleeping bag warms its occupant.
- Fleece: Fleece is a soft napped insulating synthetic fabric made from synthetic fibers. Fleece has some of wool’s finest qualities but weighs a fraction of the lightest available woolens. It comes in different thicknesses: micro, 100, 200, and 300, with 300 being the thickest and least flexible. Fleece is lightweight, warm and comfortable and is hydrophobic, holding less than 1% of its weight in water, but it retains much of its insulating powers when wet, and it is highly breathable. These qualities make it useful for strenuous physical activity as perspiration is able to readily pass through the fabric. Machine washable and quick to dry, fleece is a good alternative to wool. Fleece can generate static electricity, which causes the accumulation of dust and lint. It is also susceptible to damage from high temperature washing, ironing, and drying.
- Down: Down is a natural insulating material that provides compressible warmth and extreme light weight. It is essentially the soft under plumage (a layer of insulation underneath feathers) that geese, ducks and other waterfowl have to keep them warm and dry. A down “cluster” is soft and fluffy and will have many filaments growing in all directions. Goose down is the most popular down because its clusters will be larger than duck down, resulting in better insulation. Fill power or “loft” is how the quality and size of various goose down clusters are defined. The larger the down cluster, the higher the fill power rating. Fill power is defined as the number of cubic inches one ounce of down will fill under specific laboratory testing conditions. Ounce for ounce, goose down is the finest lightweight insulator known, natural or synthetic. Its unique three dimensional structure creates thousands of tiny air pockets that, trapped by the down fibers, provide the superior insulating ability that goose down is known for. Quality goose down is also extremely resilient – the ability to be compressed then spring back to its original shape. Goose down is also very breathable as it allows water vapor to pass through, wicking it away through the filaments while retaining the warmth in the air pockets. Its only negative for fly anglers is that if it gets wet, its thermal properties are virtually eliminated. Down forms clumps if exposed to dampness or moisture, and will mildew if left damp.
In part 3 of this series, the last of the three critical basic materials will be covered.