Sun Protective Clothing: Which Fabrics Block UV Rays?

As the owner of a sun protective apparel company, I spend far too much time researching and testing various fabrics. With the warm weather and beach vacations approaching, I thought it might be helpful to share some of my experiences.

Vetting our UPF clothing

Before my business sells any products, we get the fabric lab certified to ensure it provides a high level of UV protection. However, a lab-verified UPF certification is not the only way you can know if your clothing is helping to keep your skin protected.

What is UPF

Here's a quick side note to make sure everyone is on the same page: UPF stands for ultraviolet protection factor. It’s the fabric equivalent to the SPF standards used in sunscreen. It simply states the level of UV protection a fabric provides, and the higher the UPF, the better.

What impacts the UPF value?

There are many factors that have a huge impact on the UPF level of a garment. Knowing these can help ensure that you are keeping your skin protected. This is especially important as the summer approaches because people spend more time outdoors, the UV radiation is stronger, and the clothing we wear generally gets thinner.

Let's talk through some of those factors

Fabric

Certain fabrics have a much higher inherent protection factor than others. In my experience with testing, it seems that polyester is one of the best. I’ve seen extremely lightweight polyester shirts achieve a UPF score of 100 or more. Their cotton counterparts, comparatively, may achieve a value of less than UPF 10. Bamboo is also another fabric shown to have better UV protective qualities. It’s much softer than polyester and feels much more like your typical cotton. However, it almost always outperforms cotton with regard to the UPF value. So when you’re looking through your drawers, lean towards your polyester shirts and you’ll be off to a good start.

Fabric thickness and weight

Generally speaking, the thicker the fabric, the better. While this doesn’t mean you need to wear a ski jacket in the summer to stay protected, if a shirt is extremely thin, it’s likely also allowing a lot of UV radiation to pass through it.

Fabric condition

If you are wearing a very tight-fitting shirt, it’s likely you are actively decreasing the UV protective qualities of that fabric. As the fibers stretch out, they become less protective. The same concept holds true with old and tattered clothing. Fabrics don’t last forever, even UPF certified fabrics. Clothing that is more than a few years old will often show some signs of aging, especially if it’s frequently worn. As it ages and the fabric thins out, so do its UV protective qualities. The shirt that you purchased ten years ago that was UPF 50 may still be wearable, but it’s likely it’s not providing the same level of protection it once did.

UPF value

Look for listed UPF values. While it’s certainly not the norm, some outdoor brands will post the UPF value of their products in the product details, even if they're not being marketed as UPF clothing. This is really the only way to know for sure the true UPF value of a garment. If it’s designed specifically for sun protection, it will likely have the UPF value listed. However, if you don’t see a UPF value listed, it doesn’t necessarily mean it doesn’t provide protection; it’s likely they just never took the time to have it lab tested. So you’ll need to lean on some of the other factors we've discussed to help determine how likely it is to keep you protected.

Style

I think this goes without saying, but the more coverage the better! Regardless of the UPF value, keeping your skin protected with something is always better than nothing. Rather than a short-sleeve shirt and shorts, lean towards long sleeve shirts and pants. Even better, find a shirt with a hood to help keep your head and neck protected as well. The less your skin that's directly exposed to sunlight, the better you’ll be protected. This is even more true with apparel designed specifically for UV protection.

Keep all of this in mind

Don't just reach for the clothing you purchased because it was marketed as a UPF garment. A lot of clothing can protect us from the sun, so make sure you take that into account the next time you're getting dressed.

What do you look for when purchasing or selecting clothing?