Conventional wisdom used to be that rubbing sunblock on exposed skin offers protection from ultraviolet radiation. Clothing, on the other hand, only partially blocks sunlight, leaving a lot of skin at risk.
In the past few years, clothing has begun to sport an "Ultraviolet Radiation Protective Factor" — UPF — rating, much like the SPF factor used to rate sunscreens and sunblock. Ultraviolet light is not visible to the eye, but its effects are visible as sunburn and skin cancer.
While most people would not cover themselves with a fishnet shirt in the heat of summer, more conventional shirts also feature woven construction, albeit with much smaller holes between the threads.
"Natural fabrics, as in cottons, hemps, bamboos — they are natural, but you can't get a fine enough weave in the fiber to stop the void spaces between the weave that allow the sun to go through," says Robbin Lacy, co-founder with his wife, Angeline, of Sunday Afternoons, a Talent-based clothing company that is a nationwide leader in the design and distribution of sun-protective clothing.