Why woollen socks keep feet warmer

Why woollen socks keep feet warmer

Wool has been one of the most important fibres used in textile production for longer than you might think. The earliest evidence of domestic sheep being kept for their wool dates back to around 8000 BC, with archaeological finds showing that our ancestors had worked out how to make the necessary tools to separate the fibre strands, twist them to make a yarn and weave or knit everyday garments.

Over 10,000 years later and we still haven’t discovered or manufactured a textile product that’s such a great all-rounder as wool. Whether used in its pure form or mixed with other fibres to improve its elasticity and better retain its shape, wool is still in a league of its own, particularly when it comes to softness, comfort and temperature control. Woollen socks are one of the garments where these qualities are most obviously appreciated, with one UK manufacturer, Corgi Hosiery, still using traditional methods to produce fine woollen men’s socks and women’s socks.

Why wool works

But why is wool still unmatched as a thermal insulator for feet (as well as other parts of the body)? The key to wool’s versatility in this regard is the tiny pockets within and between the fibres which trap air thus helping to retain heat and insulate the skin from the external temperature. This, of course, has the equally beneficial effect that woollen socks will also help to keep your feet relatively cool in summer.

Of course, almost any fibre will trap air pockets but wool does it so much better than most. This is partly due to its inherent resilience. It’s stronger, like for like, than steel rope. It’s also amazingly crush resistant; you could stand a heavy piece of furniture on a wool rug for a decade and the rug would still spring back within a couple of days of the furniture being moved. You can bend a wool fibre over 20,000 time before it thinks about breaking. Compare this to a fibre of cotton which is likely to give up the ghost after bending a mere 3,000 times

Warmth when wet

Unlike other fabrics, even natural ones like cotton, wool will keep you warm even when it’s wet. Wool can soak up 30% of its own weight in water and still not feel wet to the touch. When cotton, for example, gets wet, it really does get wet. This means that all the pockets which trap warm air fill with water and can’t insulate skin against the cold – unlike wool which can get so wet that you can literally wring it out without giving up its microscopic pockets of warm air.

Wool also has a couple of other tricks up its sleeve. Its natural oils repel external moisture helping wool socks to remain drier for longer, even with sweaty feet. The fibres of wool also have natural advantage in that tiny pores tend to draw moisture towards the centre of the fibre where naturally occurring chemicals within the wool break down the hydrogen bond within the water molecule actually releasing heat.

All of this means that socks made of natural wool are still streets ahead of man-made fibres in terms of comfort, warmth and resilience. No wonder, after 10,000 years, wool socks still set the standard.

About the author

A chemistry teacher by profession, Brian Stead is also a keen walker and mountaineer and is therefore well placed to know about the theory as well as the practice of keeping warm with wool. He can be found most weekends out on the Derbyshire hills – and always with one or two pairs of spare woollen socks.

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