Backcountry Beacon

What’s the big deal about sun-protection clothing? You’ve never gotten a sunburn through your clothes, so why should you wear stuff with UPF ratings? As summer approaches, and the number of alarmingly red noses, ears, and shoulders increases, it’s good to know about your skin-saving options.

So, what’s the difference between a sun-protection shirt and a regular shirt?

All fabrics have some degree of sun protection. When the sun hits the surface of a fabric, the UV radiation breaks down. Some gets reflected, some is converted to heat, and the rest reaches your skin. The difference is that a white, summer-weight (lightweight) cotton tee usually rates at about UPF 5 or 8. That means the shirt lets in about 1/5th or 20% of the harmful UV radiation. A shirt with a UPF 50 rating means the shirt only lets in 1/50th of the ultraviolet (UV) radiation (about 2% of the harmful rays).

Harmful rays? What the heck are those?

There are three types of UV rays: UVA, UVB, and UVC. UVC gets absorbed by atmospheric gases before it reaches earth’s surface, so we don’t have to worry about that type. UVA and UVB don’t get absorbed, and they can cause premature wrinkles, leathery alligator-skin, and skin cancer. Both types of rays penetrate clouds. UVA, however, dives into the skin more deeply than UVB rays, and UVA also slips right through untreated glass. UVA can also impact your skin no matter what time of the day it is (if it’s light out, the UVA is lurking around), whereas UVB rays are most harmful between 10am and 4pm.

What about sunscreen?

Sunscreen is good, and some sunscreens now have UVA and UVB protection, but the current SPF standard doesn’t measure the amount of UVA protection, so it’s hard to know how much UVA the sunscreen really blocks. Also, people don’t always use sunscreen the way it should be used. Not in the sense that they’re eating it or snorting it, but in the sense that they don’t apply it 20 minutes before they go out in the sun (it needs that amount of time to start working), and they don’t reapply throughout the day.  Plus, for people with sun-sensitive skin, sunscreen is not enough.

Some also worry about the chemicals in certain sunscreens (the chemicals used to make a sunscreen waterproof, in particular). And, have you ever tried putting sunscreen on a squirming toddler?

OK, so SPF and UPF … which is the typo?

Neither. Those are two different types of ratings.

SPF (sun protection factor) is a rating system for sunscreen. SPF measures the length of time the sunscreen protects your skin compared to how long it would take your skin to burn without the sunscreen. If it takes 15 minutes for your skin to start to get red, then sunscreen with SPF 15 means you can stay in the sun 15 times as long with the same result (15 x 15 = 225 = 3 and 3/4hrs). Keep in mind the time of day as well (the sun will be stronger mid-day), and the fact that this is only the measurement for UVB protection.

UPF is the measurement used for fabrics. The UPF rating tells how much of the sun’s UVA and UVB radiation comes through the fabric. Both UVA and UVB are measured. Below is the percentage of UVA and B blocked:

UPF 15-24 blocks 93.3-95.8%

UPF 25-39 blocks 96-97.4%

UPF 40-50+ blocks 97.5-98%

Are fabrics treated with something to make them have a UPF rating?

Some are, and some aren’t.

That’s not much of an answer.

You’re right, that was pretty lame.

Some companies use treatments, some don’t. Here are the things that influence how much UV gets through a garment.

1. The density of the weave or knit of the fabric (denser construction = less space between the yarn = less UV).
2. The type of fiber. Lycra and polyester disrupt a lot of UV light, nylon does a good job, and wool and silk are fairly good. Cotton and hemp really don’t block much UV.
3. The specific type of dye. Some dyes use specific molecules that disrupt UV radiation, so the higher the density of those dyes, the darker the garment is, and more UV gets blocked.
4. Chemical treatments. Some companies introduce chemicals (colorless dyes) during fabric-processing, and the dyes become embedded in the material and absorb or disperse UV light.
5. Stretch and wetness also affect the fabric. A ton of stretch and water-logging increase the amount of UV the fabric lets through.

But … isn’t it mostly older people who wear that sun-protection stuff?

Actually, a lot of young surfers wear sun-rated clothing. Younger people are realizing that taking care of their skin will mean having younger-looking skin for longer (not to mention the whole avoiding-skin-cancer thing). It’s sinking in that health is more important than going bronze for a few months in the summer.  Plus many clothes with sun protection look totally casual.

Check out Lolë women’s tees, pants, and swimsuits.

For active sun-protection stuff, browse through Ex Officio gear. Ex Officio has vented,  hike-specific (and casual) women’s pants, men’s pants, women’s shirts, and men’s shirts … and hats.

For a mix of casual and active, try The North Face Women’s Boulder Lake Shirt or the Flirty Top. Guys, check out The North Face UPF clothing.

Related Posts:

• Understanding Recovery Garments
• Waterproof Breathable: Buy the Right Rain Gear
• Breathability vs Windproofing – Measuring it Up

Tags: fabric tech, SPF, technology, UPF, upf clothing