Do you want to protect your body from the sun’s harmful rays, but don’t want to pay premium prices for clothes made from high-tech fabrics that promise to protect from damaging UV rays? Think blue and red rather than yellow. Spanish scientists have found that cotton fabrics dyed deep blue or red provide better UV protection than the same fabric dyed yellow.

The researchers found that the color of a fabric is one of the most important factors in how well clothes protect against ultraviolent radiation, although scientists aren’t sure exactly how color interacts with other factors to affect protection.

Clothing dyed a shade of deep blue provided the most protection while yellow afforded the least.