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Most of you will be familiar with the phenomenon: you have bought a new towel and you first have to wash it or use it a couple of times before it starts to work properly, i.e. dry your body after taking a shower instead of smearing out the water .

My simple question is: why is this the case? Why do new towels dry better after a few uses?

Do the pores in the towel somehow have to be 'opened' after the production process which reduces capillary action in the first couple of uses? Or is it perhaps because of some coating the new towels have to protect them while kept in stores, which causes lower wettability? Or is it perhaps related to the way in which the towel dries after it has been wet?

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In the west the vast majority of towels are made from cotton, and cotton is basically cellulose. The surface of cellulose is fairly reactive (the bulk isn't unless you're a termite!) and will react with water to produce surface hydroxyl groups and negatively charged groups. Both of these lower the contact angle of water on the fibres and hence increase capillary forces and wicking.

Towels from the factory with have been treated with materials not unlike fabric conditioner. This makes the towel feel nice and soft, but it make the surface more hydrophobic and therefore less able to absorb water by wicking. It takes a few uses for this surface treatment to wear off.

You can do the experiment for yourself simply by using fabric conditioner when you wash the towel. If you compare two towels, one laundered with fabric conditioner and one not, then it will be immediately obvious that (a) the conditioned towel feels softer and nicer but (b) the unconditioned towel dries you better.

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