The Great Outdoors Stack Exchange is a question and answer site for people who love being outdoors enjoying nature and wilderness, and learning about the required skills and equipment. It only takes a minute to sign up.
Sign up to join this community
I read in an old tourist guide (from the beginning of the 20th century) that during mountain walks on sunny days one should wear a red headscarf or a hat with red lining to avoid heat stroke, because the red colour gives better protection against sunlight.
Is this really true? Does red colour actually provide better sun protection?
Heat illnesses are about heat, not light, and while the two are not unrelated, the hue of your clothing would be a very minor factor— red would not provide better or worse protection than green or blue or any other part of the visible spectrum.
The shade may have some impact: since darker clothing absorbs more energy than lighter clothing, it warms up and stays warm in sunlight. Various guides will advise wearing light colored clothing— better a light red than a dark blue, but better a light blue than a dark red.
But heat stroke can be a danger even for a well-hydrated athlete even on an overcast day. Breathability and fit are more important for choosing heat-appropriate clothing, and clothing is only one consideration among many.
(answer for previous question about sunburn)
Perhaps one would wear red clothing to hide a sunburn, or make it less noticeable. For prevention, however, there is no scientific basis to prefer any color. Sunburns are caused by ultraviolet light, whose waves are outside the spectrum of human vision. The hue of whatever garment you are wearing has no bearing at all; you can even purchase black UPF-rated clothing.
Rather, a garment's thickness, the tightness of its fabric weave, and the UV-reflective qualities of its dyes are more important.
A white colour for head protection (and all other clothes) will keep you the coolest, black will keep you the hottest. All other colours are somewhere in between.
This is because white fabric reflects the most light (all wavelengths of visible light), while black absorbs all (red reflects only the red channel).
As for the efficiency - I have sometimes noticed difference, but always so tiny. Way more important is to arrange your clothing (and headgear) so that air can freely circulate, while all parts of your body are in shade.
The smartest thing I have seen (I have not tried, but other advice from the same person was priceless) was as follows (couldn't find a picture online, sorry). Take a white non-transparent cloth (maybe half a meter by meter and a half), fix one of the long ends to your hat, the other to your backpack. I do not remember the details unfortunately, but it looked very comfortable.
