both wet and dry. Like hair, they are covered with overlapping scales that remain from the cells they are composed of. Wool fibers absorb water and swell, trapping it. This explains why wool fabric is slow to dry and why it is unique in textile fibers for making garments that are warm even when they are wet. See if your library has any books on textiles and textile fibers. I've got a book I picked up at a rummage sale that is the text for a community college course in textile science, and the description of how synthetic and natural fibers are prepared, spun and woven is very interesting. Developments in the past few decades have made some surprising changes from the straightforward mechanization of techniques that go back for millennia. For example, weft fibers can be spun into thread by air currents as the fabric is woven in sealed looms, and non-woven textiles with a wide range of properties are becoming more common for both traditional and innovative uses. A nylon shirt will dry faster than a cotton one because it holds less water after being washed. You might want to experiment with weighing samples of various materials before and after being immersed in water and wrung, squeezed or spun out. You might be interested to examine wool fibers carefully both wet and dry. Like hair, they are covered with overlapping scales that remain from the cells they are composed of. Wool fibers absorb water and swell, trapping it.