They talk about how to look for a tighter weave in the fabric, how a thinner fabric let's the uv radiation through. This is common knowledge, where I'm from. The childcare centres send out notices about it. Do you need to be scientific about basic knowledge? This is basic stuff, buddy.
I have the same issue with light, had prescription glasses and prescription sunglasses, and had to switch between the two frequently. Finally got prescription transitions and they're incredible, I no longer have to think about my glasses at all. Just put them on and go.