Textile UV Protection: Development, Testing Methods, and UPF Evaluation
In the 1990s, Japan pioneered the production of UV-protective fabrics. Currently, there are generally four ways to enhance the UV-protective properties of textiles: first, by selecting fibers with inherent UV-resistance—such as linen or polyester—as raw materials; second, by modifying the fabric structure, for instance, by increasing its thickness or density; third, by incorporating ceramic microparticles during the fiber-spinning process, which provide protection by reflecting UV radiation; and fourth, by applying UV-protective finishes to the fabric, such as treating it with UV-absorbing or UV-blocking agents, or applying a UV-protective coating to its surface.
Classification of Ultraviolet Rays and Their Effects on the Human Body
Ultraviolet (UV) radiation is categorized into three types based on its biological effects: long-wave UV radiation (UV-A, 315–380 nm), which, when absorbed in moderate amounts, promotes the production of vitamin D and aids calcium absorption—though excessive exposure accelerates skin aging and may lead to skin cancer. Medium-wave UV radiation (UV-B, 280–315 nm) can, in excess, alter intracellular DNA, impair cellular repair mechanisms, and weaken immune responses; it causes skin redness and burns, and may even lead to skin cancer and cataracts. Short-wave UV radiation (UV-C, 200–280 nm) is even more hazardous than UV-B, but it is largely absorbed by the atmosphere and rarely reaches the Earth’s surface. UV-B is the primary wavelength range responsible for the development of erythema (reddening of the skin) and UV-related cancer risks in humans.
The Development of International Standards for Ultraviolet Protection Testing
Following the emergence of UV-protective textile products, Australia and New Zealand introduced the first standard for testing such protective clothing in 1996: “Sun protective clothing—Evaluation and classification” (AS/NZS 4399). Subsequently, various other countries and organizations developed their own relevant standards. These include China’s national standard “Textiles—Evaluation of solar ultraviolet (UV) protective properties” (GB/T 18830); European standards “Textiles—Solar UV protective properties—Part 1: Method of test for apparel fabrics” (EN 13758-1) and “Textiles—Solar UV protective properties—Part 2: Classification and marking of apparel” (EN 13758-2+A1); American standards “Standard Practice for Preparation of Textiles Prior to Ultraviolet (UV) Transmission Testing” (ASTM D6544), “Standard Guide for Labeling of UV-Protective Textiles” (ASTM D6603), and “Test Method for Transmittance or Blocking of Erythemally Weighted Ultraviolet Radiation through Fabrics” (AATCC 183); as well as “UV-Standard 801,” developed by an international testing association. Furthermore, the General Administration of Quality Supervision, Inspection and Quarantine of the People’s Republic of China drafted an industry standard for import and export inspection and quarantine—”Specification for the Inspection of UV-Protective Properties of Import and Export Textiles”—which further refined the system of standards for evaluating and testing the performance of UV-protective textile products.
Test methods for ultraviolet (UV) protection performance
Currently, there is no unified international standard for ultraviolet (UV) protection testing. UV protection test methods can generally be categorized into direct testing methods and instrumental testing methods.
Direct testing method
Direct testing methods include human subject testing and color-change/fading-based testing; while these approaches are simple and rapid, they suffer from poor reproducibility. Human subject testing is susceptible to variations in individual skin characteristics, leading to significant systematic bias, and the testing process itself may potentially cause harm to the subjects.
Instrumental testing method
Instrumental testing methods include the cumulative UV intensity method, the UV-specific method, and the spectrophotometric method. The spectrophotometric method is adopted by various standards, including those from the European Union, Australia/New Zealand, the United Kingdom, the American Association of Textile Chemists and Colorists (AATCC), and China. In this method, a stable UV light source generates ultraviolet radiation with wavelengths ranging from 290 to 400 nm. This radiation passes through a monochromator to illuminate the specimen; the transmitted spectrum is then collected to determine the spectral transmittance, which is subsequently used to calculate the specimen’s UV transmittance and Ultraviolet Protection Factor (UPF) value.
Definition and Evaluation Principle of UPF Values
The UPF (Ultraviolet Protection Factor) value is defined as the ratio of the average effect of ultraviolet (UV) radiation on unprotected skin to the average effect of UV radiation on skin protected by a textile. Alternatively, it can be understood as the ratio of the time required for UV radiation to cause a specific level of skin damage (such as erythema, eye injury, or the threshold dose for carcinogenesis) when protected by a textile, compared to the time required to reach the same level of damage without such protection.
Consequently, depending on the specific evaluation criteria and variations in human skin, the same textile may yield different UPF values. In practice, the UPF value weighted according to the erythema-inducing (sunburning) effect is typically used as the representative value.
Conclusion
The UV-protective performance of textiles is closely linked to their fiber composition, fabric structure, and finishing processes. As the range of applications for such products continues to expand, various countries have established their own testing and evaluation standards. Spectrophotometric analysis and the Ultraviolet Protection Factor (UPF) have emerged as key methods and metrics for assessing the UV-protective properties of textiles.
However, significant differences persist across national standards regarding sample preparation, testing conditions, UPF classification, and labeling requirements. How do these various standards evaluate the UV-protective performance of textiles? What specific requirements do they impose for sample pre-treatment and product labeling? In the next installment, we will examine several major standards—including those from Australia/New Zealand, Europe, the United States, and China, as well as the UV Standard 801—and compare their respective testing methodologies and evaluation criteria.
Reference: China Dyeing & Finishing (2009 No. 03)— “Current Status of Testing Standards for the UV-Protective Properties of Textiles”. If any copyright infringement is detected, please contact us.
