A relatively new rating designation for sun protective textiles and clothing is UPF (Ultraviolet
Protection Factor). Unlike SPF (Sun Protection Factor) that traditionally uses human sunburn
testing in a laboratory environment, UPF measures both UVA and UVB radiation transmittance
through a fabric which might hit the skin or percent of radiation which can go through the
fabric.. The SPF is the amount of UV radiation required to cause sunburn on skin with the
sunscreen on, as a multiple of the amount required without the sunscreen.
Each type of fabric has it own UPF rating. For example dark blue denim will have a higher rating
than a fine silk. Factors that affect the level of sun protection provided by a fabric, in
approximate order of importance, include weave, color, weight, stretch, and wetness.
Ray Bloc has been tested on numerous fabric and increase the UPF rate of all the fabrics. Trek 7
took a common type of tee shirt cotton fabric. We left one swatch untreated and the other we
treated with Ray Bloc. The samples were sent to an independent lab for UPF rating. The results
were dramatic where the untreated cotton fabric received a UPF rating of 15 which was poor.
The fabric treated with Ray Bloc had a UPF rating of 50 or which is excellent increasing the UPF
rating by 35 points. It has been tested on a variety of fabric significantly increasing the UPF buy
30 points or more.
|UPF 15 - 24
|UPF 25 - 39
|UPF 40 - 50+
A rating below 15 is considered unacceptable in protecting an individual from UV radiation.
Wikipedia Information on UPF Sun Protective Clothing