A UV resistant fabric is one that does a good job of preventing harmful UV rays from passing through it to your skin. There are several factors that determine how well a fabric resists UV rays, such as fiber type (polyester and nylon do the best job of blocking UV light), construction details and color. Fabrics that are dyed darker or brighter provide more protection than those that are not (this is because the benzene atoms in the dye molecules absorb UV rays). Chemical treatments that also bind to and disrupt UV rays can enhance UPF, as can specific weave patterns.
What fabric is UV resistant?
Fabrics are generally rated for their sun-protective performance based on their Ultraviolet Protection Factor (UPF), which protects against both UVA and UVB rays. To earn the label, a fabric must pass a standard test that measures how much of the sun’s rays can penetrate the fabric and reach your skin. The best way to check a fabric’s UV protection is to hold it up to the sun. If you can see through it, it isn’t very protective.
Many textile manufacturers make UV protective fabrics, either by combining synthetic, tightly woven polyester with nanofibers and dyeing it in darker colors or by treating the yarn with chemicals that are effective at absorbing UV radiation. Some of these additives are incorporated during the production process, but others must be added afterward (by coating or impregnation). Adding chemical UV protection to fabric has raised sustainability concerns, as the additives may be toxic to human skin. However, recent research has found that natural extracts of eucalyptus leaves and tea extract can significantly improve the UV-blocking properties of cotton textiles.