Sun protection is as important to boaters as securing a life jacket. We slap on sunscreen with an SPF (sun protection factor) of 15 or greater. Or, increasingly, we are encouraged to cover our skin. But does every fabric offer the same protection? We did some rudimentary tests to verify the UPF — ultraviolet protection factor — rating for a collection of popular outdoor garments.
UPF Technology: All fabrics block UV light. Some do it better than others. You’ve noticed UPF 50 or UPF 30 labels on outdoor wear. But what do they mean?
UPF ratings are determined by measuring the amount of UV light transmitted through a fabric. The test standards were first set by Australian scientists and adopted by the American Society of Testing and Materials. Our tests are not as sophisticated as ASTM’s, but they provide a valid comparison and ratings confirmation between various UPF-rated garments. They make you better equipped to make boating in the sun safer and more fun.
How We Tested — Myths We Busted
What we tested: We tested 10 UPF-rated garments and five unrated garments. We tested the unrated garments to challenge an urban legend we’d heard: Natural fabrics don’t make good UV barriers.
How We Tested: 1. BoatingLAB used an industrial UV sensor normally employed to measure UV light used to cure resins in molding processes. 2. Our UV light source was a simple black light. 3. We used a spacer to maintain exact distance between the UV light, fabric and sensor each time.
Results: Our test procedures were crude by ASTM standards but furnished relative results that showed consistency between the manufacturer UPF rating and UV protection we recorded. With such small percentage differences between the established ratings, and no way to measure margin of error, we can’t confirm or dispute the absolute number of any UPF rating. Our results show how various garments performed in our test regimen.
Myth Busted: Synthetics are Better at Blocking UV
Tightly woven cotton blocked as much UV as synthetics.
Myth Busted: Wet Fabrics Lose UV Protection
We found extremely minor and nearly unmeasurable differences between wet- and dry-fabric UV transmission.
Myth Busted: Fabric Coatings are Required
Some manufacturers, like Simms, attribute UV blocking to a coating. Sun Guard laundry additive worked too. But fabric density was just as important in many products tested.
Design: Columbia relies on the UV resistance of nylon and the tight weave of the fabric to reflect and absorb UV rays. Omni-Freeze technology is reported to lower fabric temperature when in contact with sweat. To enhance comfortable feel, Columbia has incorporated “air gill” vents that allow air to enter the garment and circulate out the back vents.
Microscopic: Nylon is inherently UV filtering, and this product’s filtration is aided by a tight denier or weave.
Design: This cool, breathable fabric dries quickly, thanks to wicking properties of the fibers. The comfortable, light, breathable fabric is fortified with Simms COR3 coating that has antimicrobial factors, repels bugs and enhances its UPF rating. Like the Airgill, it has long sleeves, which can be buttoned up for a short-sleeve look. It makes a great sports shirt on shore.
Microscopic: The fabric is light and light-colored, but a tight weave and UV-absorbing treatment keep its UPF high.