A comparative study of fabric protection against ultraviolet-induced erythema determined by spectrophotometric and human skin measurements.

Historically, a textile's ability to protect against ultraviolet radiation (UVR)-induced erythema has been based on its UVR transmission. However, due to the nonuniformity of the fabric structure of a textile and its resultant nonuniform transmission, the above prediction may not hold. The fabric protection factors (FPF) of 5 metal meshes, to simulate the weave pattern and yarn dimensions of typical fabrics, and 6 textiles with variable construction (woven and knitted), fibre type and dye were determined using a spectrophotometric assay and human skin testing. All 5 meshs and 5 of the 6 textiles allowed spectrophotometric prediction of their FPF compared with off-skin (2 mm) human testing. However, on-skin human testing FPF were generally significantly lower than both the off-skin and spectrophotometric estimates. Although evidence is presented that the nonuniform nature of a textile's structure does influence its FPF predictability, in practice, properly conducted spectrophotometric analysis may yield the most typical indication of the protectiveness of a fabric against UVR-induced erythema.