In the summer my mother was sitting in the garden having a lunch with friend, sitting in the afternoon sun. She was a bit perturbed that night to discover she burnt her arms. She declared that she was wearing a shirt, so how could the sun have burnt her skin. I looked at the shirt which was a loose floaty summer shirt made out of a very thin woven cotton.
I had to explain to her that not all materials are going to protect you from the sun it all depends on the density of the material. So here for the benefit of my mother, and anyone else interested, is….
What makes a fabric protective from Ultra-violet rays, or in other words the sun?
When it comes to blocking the sun’s rays from getting to your skin Bohn swimwear has a rating of UPF 50+. This means that 97.5 % to 99% of ultra violet radiation does not get through the material. But how does this material achieve this protection when other fabrics don’t? It is down to the weave structure of the fabric. This is sometimes known as the denier rating, which is the thread count per inch of fabric. Just like when you buy sheer or thick tights. The thinner tights will have a smaller denier rating, less threads per inch, e.g., 15 denier tights. Whereas thick tights will have a denier rating of 40 or 60, so have more threads per inch.
The tighter construction of these fabrics (whether knitted or woven) minimizes the space between the yarns, which in turn minimizes the ultra violet rays that can pass through the fabric to the skin.
Fabrics that can block UV radiation will not only have a denser weave and more threads per inch, but usually be in darker colours. The components of some darker dyes and the concentration in which they are used make them better for deflecting more UV rays. Some like black dyes will absorb none at all. But the ultimate UV protection of fabrics will be down to the type of dye used, just because a fabric is darker, does not automatically mean it has UV protection, you must still look for the UV rating of the garment.
If you are fair skinned or need sun protection, be safe in the sun.