Be aware light clothing can still transmit enough light to burn. My bullshit test is “can I look at the sun through this fabric or does it hurt?”. It’s a little conservative, but it’s good enough for me if I plan to be out for 8 hours. I actually just got burned shirtless last week on one side. With a light, black, sports shirt the next day, I was in mild burning pain when the sun hit my burned side. It wasn’t just heat, as lifted the fabric off my skin still hurt the same.