Why Are Air-dried Towels So Stiff?

Drying your laundry outside in the sunshine is a simple thing you can do to save energy, and sun-dried fabric just smells good. However, there are some items of laundry for which air drying just doesn’t work, and towels are one of them. Why is it that a towel dried outside on the line comes into the house as rigid and abrasive as a piece of beef jerky? The question has stumped scientists for some time, but a research team from Hokkaido University and the Kao Corporation in Japan thinks they might have cracked the air drying code — and in the process, they might have learned something important about water. Most fabrics — with the exception of silk and wool — that aren’t made out of plastic are made out of plants. Cotton is made from the fluffy seed casing of a small shrub, while rayon and similar fabrics are made out of wood pulp. Plants contain a lot of cellulose, which is great at absorbing water. That’s why we make towels out of cotton instead of polyester. Water molecules cling to cellulose and climb along it through a process called capillary action. That small amount of water binds to the surface of the towel and acts like glue to hold the cotton fibers together. The mechanical force that happens when clothes are tossed around in a dryer breaks the hydrogen bonds in the bound water, which is why your towels come out soft and fluffy.