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When you wash a duvet cover, why does other washing end up in it? (continued)

Lorna Cox, Cambridge, UK

The question about duvet covers in the wash was answered in the Last Word some decades ago. One answer given at the time was that any decorative printing on the fabric could cause a differential stiffness of the outside and inside surfaces, promoting inversion in the washing machine. This inversion would then result in items finding their way inside the cover, especially if the machine had been overloaded.

Since reading that answer, I have always washed duvet covers inside out and this has solved the problem. In my experience, it hasn’t been necessary to close the poppers or other fastenings. Occasionally, something may end up inside, but very rarely. Life is too precious to be spent doing and undoing poppers and the cover will dry faster on a washing line if the two sides are free.

James Fradgley, Wimborne, Dorset, UK

Perhaps the things inside the duvet cover are experiencing something akin to thermophoresis, the movement of particles in a temperature gradient. As items are thrown about in a washing machine, smaller articles of clothing like socks are likely to have higher velocities than larger ones, such as shirts.

You might suppose that if a sock goes into the duvet cover, the odds are good that it will zoom back out again. But when it comes to a larger item, the chances may not be so good, as friction could play more of a role. On the other hand, by the same logic, it is harder for a shirt to get stuck in a duvet cover than a sock.

Have any studies been done to estimate if there is a size discrepancy at the end of the wash between what is in the duvet cover and what isn’t?

John van Someren, London, UK

Because it is a lobster pot made of cotton.

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