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Name: Gary F.
Status: other
Age: 40s
Location: N/A
Country: N/A
Date: 5/20/2003


Question:
This question will settle an argument between myself and my wife and son (who agree against me). My son and I are basketball referees. One day he was complaining that his feet were extremely hot because he had worn black socks that day as opposed to white. He had shoes on all day and long pants that covered the socks. I told him that it did not matter if they were black or white, (assuming like materials of course). I clarify long pants and shoes to eliminate heat absorption from the sun, his socks being covered, along with the fact that we were inside a gym all day. After reading the question from Dallas T. from Saturday, April 20, 2002, I may even change my tune to think that his black socks should even cool faster! Who is correct?


Replies:
Gary,

I cannot provide data which would help you win this argument; the data would have to be collected for several individuals and several black vs. white sock manufacturers.

My inclination is to agree with YOUR argument against your son and wife. My suspicion is that for a given set/type of sneaker/shoe, the temperature of the foot related to a sock would have more to do with the type of sock fabric and its weave and less to do with its color. Certain fabrics absorb sweat, thereby pulling it away from the body; their thickness and weave would influence the amount of this which could occur. Some types of fabric have insulating properties, others do not. Some fabrics, upon microscopic examination, could be seen to have a 'loose' weave with a lot of empty air space, while others could be seen to have a tight weave with less air space between threads.

I feel, but without supporting data, it would be incorrect to make a blanket statement relating resultant foot temperature simply to the color of a sock. To me this would be like trying to estimate fuel economy of a car based upon its color. Clearly there are factors which directly influence the observed data and my reasons stated above cause me to doubt your wife and son's argument. As I said, however, to prove this theory one would have to collect data eliminating variation in fabric/weave/thickness type and focusing directly on color.

Thanks for using NEWTON!

Ric Rupnik


Color has no effect that I can discern on conduction of heat. There are three ways for heat to move... conduction, convection, and radiation. In the case of socks, the mode of heat transfer is by far conduction. The type of fabric would be far and above the most important...cotton, wool, acrylic, thickness etc.

Peter Faletra


This is a difficult "experiment" to keep "everything else being the same" but if you think of the energy inputs and outputs of feet, socks, shoes, and the rest of the world, body heat is by far the major heat input to socks-on-feet, and evaporation of water from sweat is by far the major heat output at about 5.5 Kal /ml (here 5.5 Kal is "food calories" -- that corresponds to 5.5 k.cal thermal energy). What is difficult to control, and I suspect is the case is, black socks and white socks are not the same fiber content. The more hydrophobic the sock the more quickly water will evaporate from it (for example, Polypropylene or Nylon fabrics dry much faster than cotton ). This is one of the reasons swim suits are made from fibers like Nylon.

Vince Calder


Gary,

I cannot really settle your argument, but I have a couple of thoughts. He cannot really say that his feet were hot due to the socks if he had nothing to compare with. Perhaps his feet were just really hot, or his sneakers did not let his feet breathe. You have got to make it scientific. Get identical kinds of socks, made by the same manufacturer, with the same fiber content, of the same thickness; the only difference being the color. Wear one color on one foot and the other color on the other foot. Play all day, then compare. My gut feeling, the black socks might have had more polyester or nylon in them. It does not breathe as well as cotton. If you have already taken this into account, then you have blown my theory and I do not have an answer.

Martha Croll



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