Wear Layers to Keep Warm Inadequate clothing lets the warmed air around the body escape. Proper clothing and protection trap the warm air around the body. The key is to keep warm and dry. The first layer lets the skin breathe. Underwear, socks and glove liners of polypropylene or knitted silk lets perspiration escape from next to the skin. The second layer absorbs perspiration without allowing heat to escape. Wool is ideal because it stays warm even when wet. It also comes in many thicknesses. The third layer traps heat in, and keeps water or dampness out. A quilted coat filled with down or a lightweight microfibre is ideal. If it's not waterproof, wear a water- resistant shell or windbreaker.