Dark Colors Keep Out Sun's Harmful Rays

Oct. 16, 2009 -- Darker colors in cotton fabric provide better protection against the sun's harmful ultraviolet rays than lighter tones, new research indicates.

Scientists in Spain say people should "think blue or red" instead of yellow when choosing clothing, because the darker hues on cotton fabrics offer better skin protection against the sun.

Their study is published in Industrial & Engineering Chemistry Research.

Ascension Riva, PhD, of the Universidad Politecnica de Cataluna, and colleagues used computer models to estimate levels of UV protection achieved with three fabric dyes -- red, blue, and yellow.

The researchers dyed cotton fabrics a range of red, blue and yellow shades and measured the effectiveness of each dyed fabric to protect against UV light.

Fabrics with darker or more intense colors had better UV protection, the researchers say, and yellow shades offered the least.

The scientists say clothing manufacturers could use information from the study to design clothing that provides better protection against harmful rays.

The researchers note that gaps exist in knowledge about exactly how color interacts with other factors to influence a fabric's ability to block harmful rays. They add that numerous studies have concluded that lighter-colored sportswear worn in summer months does not provide enough protection.

The researchers write that "the color of cotton woven fabrics is a factor that has a remarkable influence on their protection against ultraviolet radiation" and that "the diffuse transmittance of ultraviolet radiation through the fabrics diminishes when any of the studied dyestuffs is applied."