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SUN1 |
Support Group for Sun Sensitive People
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When choosing clothing for sun protection, select clothing to cover as much skin as possible. High or turned up collars, long sleeves, and long pants or skirts are good choices. Clothing is generally a good UV blocker. Lighter weight, cooler clothing may not have as great a sun protective value as clothing made from heavier fabrics such as denim.
Fabrics should block or reflect as much light as possible. Heavier, tightly woven, dark fabrics generally protect better than loosely woven, light colored fabrics.
The sun protection effectiveness of fabric can be measured in different ways.
Common sense can be used to efficiently test fabric for the quality of protection against the sun. A useful test is simply hold the piece of clothing up to a strong light source such as a light bulb. If you can see images through the item then it probably has a UPF value of less than 15. If light gets through the cloth but you can't really see through it than the item probably has a UPF value between 15 and 50. If the fabric completely blocks all light than the item probably has a UPF value of greater than 50. Traditional heavy dark blue cotton denim is an example of a fabric that can test with a high SPF value of 50+.
SPF (Sun Protection Factor) rating of fabrics and clothing
The sun protection value of fabric is more a function of the hole size of the fabric mesh than the particular fabric type. The tightness of the weave is an important determinant of sun protection. Bleached cotton has an SPF of 7 or 8. Cotton and polyester/cotton blends offer comparable protection. Typical summer shirt fabrics only have an SPF of 6.5 (University of Iowa).
Environmental influences including laundering, humidity, wetness, and degree of stretching play a major role in fabric ability to provide protection. “Each fabric must be tested to determine its ability to protect from solar radiation, as this cannot be known from visual observation nor calculated from descriptions of the fabric’s composition and structure.” (Menter and Hatch).
Protecting against UV light with clothing or UPF: Ultraviolet Protection Factor
Another type of measurement is ultraviolet protection factor (UPF). Unlike SPF that measures the amount of skin redness, UPF measures the amount of UV radiation that penetrates a fabric and reaches the skin. The UPF rating indicates how much the fabric material reduces UV Radiation (UVR) exposure. A UPF rating of 50 will allow 1/50th of the sun's UV rays to pass through the fabric and a material with a UPF rating of 20 would only allow 1/20th of the UVR falling on its surface to pass through it.
The color and density of the fabric effect its ability to provide protection from the sun. Darker-colored fabrics are more effective than lighter at blocking out the sun. For instance, the UPF of a green cotton T-shirt is 10 versus 7 for white cotton, and a thicker fabric such as velvet in black, blue or dark green has an approximate UPF of 50. (Skin Cancer Foundation)
Figure 1: Tight weave of fabric blocks sun resulting in greater protection and higher UPF and SPF
Unbleached cotton provides higher levels of UPF protection.
Shiny and satiny fabrics can provide higher levels of sun protection. Both lustrous polyesters and shiny silk can be highly protective.
Darker color fabrics provide greater protection from UV rays than do lighter color fabrics.
It is also important to note that fabrics are significantly less protective when wet.
Less UVR passes through tightly woven or knitted fabrics. Fabric is significantly less effective at sun protection when stretched.
Worn and faded clothing might have less ability to provide sun protection.
Australia introduced the UPF system for a standardized testing method and a clothing label classification in 1996. UPF ratings range from 15 to 50 with higher ratings indicating more effective blocking and therefore better protection for the wearer of a garment made from the fabric. Fabrics that test higher than UPF 50 are rated as UPF 50+. (ARPANSA) Other nations including the UK and the USA followed by adopting the UPF measurement standards and labels for consumer awareness.
In a study (Gambichler et al) of 236 typical summer fabrics, a third of summer clothing provided insufficient UV protection and only half of the fabrics had UPF 30+, the UPF recommended by the European standard. Wool, polyester, and blends were likely to provide sufficient UV protection (UPF 30+), while only 30% of the cotton and linen were among the fabrics with UPF 30+ protection. Fabrics with black, navy-blue, white, green, or beige provided most frequently UPF values of 30+. The most striking result is the fact that 78 fabrics (33%) had insufficient UV protection with UPF of less than 15.
Special fabrics and clothing made for UV protection
Some fabrics are specifically made for UV protection. These innovative high tech fabrics are designed to protect against the sun and UV rays.
Some fabrics are treated to improve the UPF rating. This is usually done if the base fabric has a low natural resistance to UVR. Treatment with a UVR absorber, generally during manufacture, can result in a fabric with a higher UPF rating that still retains the comfort properties of the original fabric. Many dyes absorb UVR and therefore increase the UPF rating of the fabric. Some UVR absorbers behave like colorless dyes. They bond to the fabric in a similar way, and have a comparable permanency to colored dyes.
Sun protective clothing items are sold with brand names unique to a variety of specialty retail shops.
Laundry additives to increase sun protection of clothing
Some laundry detergents include "optical brightening agents" to make white clothing whiter and brighter. The accumulated "optical brightening agents" after repeated multiple washings with these detergents could increase the UPF rating of clothing.
SunGuard works by washing an invisible UVB and UVA protection into clothing. The active ingredient TINOSORB® FD is a UV protectant from Ciba Labs. SunGuard invisibly penetrates a garment's fibers – so your clothes absorb UV rays rather than allowing them to pass through fabric. A single treatment of SunGuard will block over 96% of UV rays from passing through clothes, and provide a UPF 30 protection rating. Add one package of SunGuard along with laundry detergent and use the hottest water safe for your fabric, allow at least 15 minutes of agitation or soaking time, then rinse and dry as usual. The protection lasts for up to 20 washings. SunGuard is a product of Phoenix Brands LLC, whose portfolio of widely recognized household brands includes Niagara® Spray Starch, Rit® Dye, and Ajax®. SunGuard is often known as Rit SunGuard. The manufacturer says product will not change clothing color or texture and is safe for all washable fabrics. (Phoenix Brands)
Department of Dermatology, University of Iowa Hospitals and Clinics, Health topics: Sun protection and sunscreens, modified August 2006.
Gambichler, T., Rotterdam, S., Altmeyer, P., and Hoffmann, K., Protection against ultraviolet radiation by commercial summer clothing: need for standardised testing and labeling, BMC Dermatology 2001, 1:6.
Menter JM, Hatch KL., Clothing as solar radiation protection. Elsner P, Hatch K, Wigger-Alberti W (eds): Textiles and the Skin. Curr Probl Dermatol. Basel, Karger, 2003, vol 31, pp 50–63
Skin Cancer Foundation, Protective Clothing, 2011.
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We are not physicians, we are people trying to learn about our conditions and better our lives. We try to be accurate, but the articles and advice may have errors, become out-of-date, or even give bad advice. |