It has been thought that wearing a white in the sun will keep us cool because white reflects the heat, and wearing black in the sun make us hot? This to a certain degree (wearing white will keep us cool) is correct until you start thinking about two other factors; the heat from our own bodies and UV protection.
White T-Shirt Or Black T-Shirt
In actual fact to dress for hot weather we should probably be taking cues from the Bedouin who wear loose black robes. The way that white t-shirts are constructed in comparison to a darker tee is differentiated by the dye that is applied and the material. A darker material is obtained by the introduction of dyes to the material which absorb more UV rays than the simple white cotton, which is generally just bleached from the original natural colouring of the fabric to get the fresh white consistency. The white material often has more holes than a heavily dyed fabric which is why you often see the same styled shirts with a different Ultraviolet Protect Factor (UPF) rating. The type and thickness of fabric will make a difference; for instance a thick heavy woolen fabric, like a Bedouin would wear, would have a higher UPF rating than a thin cotton white tee. However, there is something to be said that although useful in terms of UV protection I’m sure that not all of us want to be walking around in thick heavy woolen clothes. Therefore a compromise would be a cotton/polyester tee; but make sure you choose a black tee over a white tee when thinking about UV protection.
Body Heat
So back to the original question, wearing a white t-shirt in the sun will keep us cool because white reflects the heat. Correct, until you start thinking about your body heat which in fact is a lot closer to the t-shirt than the sun. Yes, white will reflect more heat than black but it will also reflect the heat from your body back towards your body. In the case of a darker material, yes this will absorb the energy from the sun but will also absorb the heat from your own body a lot more consequently keeping you cooler. This paired with a loose fitting black tee allows cooler air to enter from underneath and with heat evaporation from the top, in entirety this creates an air flow and therefore results in cooling the body. Plus if you think about it if the only reason not to wear a black t-shirt is because they get hot due to absorbing the heat from the sun, having a loose fitting t-shirt is also going to reduce the amount that the fabric touches the body.
In conclusion, not only will a darker dyed fabric give you a better UV protection than a lighter material but also in the case of a loose fitting fabric cools you down more too. So forget everything you’ve previously thought, some scientist somewhere has proved this correct, and they even said so on QI – which means it is definitely true!
So you can wear black in the sun! Plus black is slimming anyway right….?
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