Fabrics made of nylon, wool, and cotton can naturally absorb some UV radiation. Many of these fabrics have threads that are made from elastic to pull the fibers together, tightly. This reduces and tiny holes in the clothing that may allow UV light to touch the skin. Polyester and Lycra are much more protective than cotton and wool as they absorb more UV rays. Commonly, fabrics that are light in weight do a better job of protecting skin than heavier fabrics.