A relatively new rating designation for sun protective textiles and clothing is UPF (Ultraviolet Protection Factor). Unlike SPF (Sun Protection Factor) that measures only UVB, UPF measures both UVA and UVB.
Developed in 1998 by Committee RA106, the testing standard for sun protective fabrics in the United States is the American Association of Textile Chemists and Colorists (AATCC) Test Method 183. This method is based on the original guidelines established in Australia in 1994.
Summary UPF Testing Protocol
AATCC 183 method defines the UPF rating for a fabric/textile as the ratio of UV measured without the protection of the fabric (compared to) with protection of the fabric. For example, a fabric rated UPF 30 means that if 30 units of UV fall on the fabric only 1 unit will pass through. A UPF 30 fabric that blocks or absorbs 29 out of 30 units of UV is therefore blocking 96.7% UV. UPF tests are normally conducted in a laboratory with a spectrophotometer or a spectroradiometer.
AATCC 183 should be used
in conjunction with other
related standards including
American Society for Testing
and Materials (ASTM) D 6544
ASTM D 6603. ASTM D
6544 specifies simulating
the life cycle of a fabric
so that a UPF test can be
done at the end of a fabric's
which is when most fabrics provide the most reduced level of UV protection. ASTM D 6603 is a consumer format recommended for visible hangtag and care labelling of sun protective clothing and textiles. A manufacturer may publish a test result to a maximum of UPF 50+.
While there is some correlation between the amount of visible light that passes through a fabric and the amount of UV that passes the same fabric, it is not a strong relationship. Based on some of the new-technology fibers and textiles designed for the sole purpose of UV blocking, it is not always possible to gain a good understanding of the UV protection level of a fabric simply by holding it up and examining how much visible light passes through the fabric.
Sun protective clothing and textile/fabric manufacturers are currently a self-regulating industry in North America, prescribed by the AATCC and ASTM methods of testing.
Gies, H.P., Roy, C.R., Elliot, G., & Zongli, W. (1994). "Ultraviolet Radiation Protection Factors for Clothing". Health Physics 67 (2): 131-139.
Gambichler, T., Rotterdam, Altmeyer, P., & Hoffmann, K. (2001). "Protection against ultraviolet radiation by commercial summer clothing: need for standardized testing and labelling.". BMC (BioMed Central) Dermatology I: 6-9.
American Association of Textile Chemists and Colorists (AATCC) Test Method 183
American Society for Testing and Materials (ASTM) Standard D 6544
American Society for Testing and Materials (ASTM) Standard D 6603
Stanford, Duncan G., Georgouras, Katherine E. & Pailthorpe, Michael T. (1997). "Rating clothing for sun protection: current status in Australia". Journal of the European Academy of Dermatology & Venereology 8 (1): 12-17.