The Truth About UV Clothing
How does one test the latest UV blocking fabrics emerging on the market?
Curiously, a number of light and laser testing facilities do not currently use the latest pending standard involving the averaging of invitro (lab) and invivo (human) field-testing and instead, choose to measure using the single standard Menzies/Az 1994 protocol, which is much more economical but far less accurate for the lightweight but complex yarn fabrications such as those employed in some highly regarded apparel products). Based on the laboratory credentials, some manufacturers have chosen to use an independent photonics lab that is well respected internationally in their field and is known to be very comprehensive in their test results. The facility created disciplined parameters for UV testing based more on the future interests of the industry. However, this method is also a much more expensive testing process.
The method employed by textile manufacturers seeking UV ratings for “woven yarns” is perhaps the one that is more incorrectly but commonly used today – and the test protocol is measured for stretch type fabrics used mainly for swim and active-wear. As leno fabric is a woven, with various degrees of porosity, such tests can still produce erratic results, especially with ventilated weaves and if the dyeing process involves optical brighteners and/or titanium dioxides in the pigments. These variables can wreak havoc on accurate results. What can create controversy with the new fabrics?
As with any consumer goods purchase involving new and evolving technologies, one must be careful in relying on poorly researched magazine or newspaper articles, which can be quite misleading. Be sure to read the product detail descriptions on clothing tags or, if purchasing on-line, the description of a product on the web site. If a product does not say, for example, that it offers up to a 97% block, one should not assume that it does, even if other items within that product line so say so on the tag or in the on-line product description.
Do colors affect the UV protection level?
Yes, color is also an important point when considering clothing for the purpose of sun-block: Darker colors (especially indigo, navy and black) perform better because they can absorb more UV; however the trade-off is that they can create heat as a by-product. Lighter colors will reflect more, especially fabrics with optical brighteners. All everyday existing fabrics can be considered to have a sun-protective value, but unlike the creams that can have lower values, the current UPF rating system begins at the minimum UPF level of 15 to permit an independent classification.
When the ASTM D13.65 committee was created for the addendum to sun-protective fabrics in 1996, a number of textile manufacturers and light and laser specialists invested about 5 years in planning the testing protocol. Even today, it is still a work in progress and will be updated annually because the results are still inconclusive and merit more study. Naturally, some of the unique textiles being created today are, under current lab conditions, misunderstood.
