A number of fabrics and textiles in common use today need no further UV-blocking enhancement based on their inherent fiber structure, density of weave, and dye components, especially darker colors and indigo dyes. Good examples of these fabrics contain full percentages or blends of heavy-weight natural fibers like cotton, linen and hemp or light-weight synthetics such as polyester, nylon, spandex and polypropylene. Natural or synthetic indigo-dyed denim, twill weaves, canvas and satin are also good examples.[citation needed] However, a significant disadvantage is the heat retention caused by heavier-weight and darker-colored fabrics.[citation needed]