What's the difference between sunscreen fabric and ordinary fabric? Do you really need to pay extra for fabric with an SPF rating?
Ordinary Fabrics and SPF
"SPF" stands for "Sun Protection Factor." An SPF of 15 means that you can stay in the sun without getting burned 15 times longer than if you didn't have any protection. Sunscreen lotions are usually rated according to their SPF level. Fabrics may also be rated according to UPF, Ultraviolet Protection Factor. This refers to the amount of ultraviolet (UV) light that passes through. It's UV light that causes sunburn. A UPF of 15 means that the amount of UV light getting through is only 1/15 what it would be without protection.
Ordinary fabrics have a wide range of SPF/UPF ratings. Thick, tightly woven, and dark fabrics protect against the sun very well. But these kinds of fabrics may not make ideal summer clothes. Thinner, more loosely woven, and lighter fabrics can have a UPF as low as 5.
Cotton and Rayon
Thinly woven cotton and rayon, two favorite summer fabrics, have relatively low UPF. Depending on the weave, color, thickness, and other factors, UPF may reach as high as 15, but can be much lower. A thin summer T-shirt may have a UPF of only 5; if it gets wet, UPF can drop as low as 3. On the other hand, sturdy denim provides excellent sun protection.Wool and synthetics, such as polyester, tend to have higher UPF. Again, though, it depends on the weave and thickness.
Choosing Sunscreen Fabric
To be labeled as "sun protective," fabrics don't need to be treated with any special substance. They just have to keep out a substantial portion of the sun's UV rays. According to the U.S. Federal Trade Commission, fabric must be at least UPF 15 to be called sun protective. Anything above UPF 50 can be labeled UPF 50+; before you pay extra for 50+, remember that these fabrics might not offer much more protection than something labeled UPF 50.
Sunscreen fabrics are usually woven tighter and are darker in color than ordinary summer clothes. They may lose UPF effectiveness if the fabric is stretched out, if it becomes wet, or after many washings. (Some fabrics can gain UPF when wet, however; it depends on the specific properties of the garment.)
Laundry and Sun Protection
Washing clothing doesn't always make it less sun-protective. Research at the University of Arizona suggests that washing old cotton shirts can actually raise their UPF. That's because some laundry detergents contain brightening factors that absorb some of the UV rays instead of allowing them to pass through. In the future, a special laundry additive may be available to specifically increase fabric's UPF.
Staying Safe in the Sun
Over time, too much sun can lead to wrinkles, skin cancer, and other skin problems. Clothing made from sunscreen fabric isn't enough to provide full sun protection. Both adults and children should use a high-SPF sunscreen on all exposed skin. A broad-brimmed hat can also help keep the sun off delicate facial skin.
Sunscreen Fabric vs. Sunscreen Lotion
Even though long sleeves and pants may seem like too much clothing for summertime, wearing sunscreen fabric does have some advantages over relying solely on sunscreen lotion. Even the best "waterproof" lotions can come off when you sweat, leaving you unprotected even if you haven't been swimming. It's easy to miss a spot or to use too little suntan lotion. To be fully effective, lotion must be applied 30 minutes before you go out into the sun and reapplied often.
Fabrics, on the other hand, cover evenly: there won't be any surprise sunburn where you missed the middle of your back. You can toss a shirt and loose, long pants on just before going outside. And, although they may become less effective when damp, their protection won't fail entirely if you sweat.
Sunscreen Fabrics for the Back Yard
Sunscreen fabric shades and awnings can help keep the sun off patios and play areas, offering extra protection not just from harmful UV rays but from summer heat, as well. The idea is that these special shades actually bounce back the sun's rays, preventing heat from building up beneath. Manufacturers claim that their fabrics can block as much as 90% of the sun's heat.