Why are long johns AKA thermal underwear in the US so often full cotton or polycotton blends? There are literally 0 reasons to put cotton in a base layer in a cold environment. People don't wear thermal underwear outside of cold conditions. It seems like this is an article of clothing that just shouldn't exist, and yet they're sold all over the place. Am I overlooking some use case here? The only thing that I can come up with is "alternative to pajamas when you're sitting in a heated cabin and not doing anything and don't plan on going outside at any point".
>>2755782Lighter colors are better. If you're concerned about sun exposure, get a wide brim hat. I would use cotton; it will probably maintain shape better than polyester or nylon. Also, you can dunk it in the water periodically and the evaporation from it will help keep your head cool.
If you don't care about looking like a dweeb, you can also get the ones that have a flap hanging down that provides extra sun coverage to your neck. On the opposite end of the fashion scale, you could get a straw hat, but they aren't as durable and you'll want to make sure the weave is fairly tight so the sun doesn't go straight through it.
