[thedoc (OP)]

Sarah Turnbull  asked the Naked Scientists:
   
As a knitter, I am a bit worried about the talk of microwaving or boiling a wool hat!

A combination of exposure to water, high temperatures (or sudden temperature changes) and agitation can cause wool to felt (i.e. shrink - a bit like turning your hair into dreadlocks).

Felting is irreversibe, so the hat could end up teeny tiny!

Some wool is treated so as not to felt. This is done by a chemical process to remove some of the tiny scales on the surface of the wool. It is usually marked as "machine washable" or "superwash". However, I'm still not sure it would be suitable for microwaving!

A safer way to kill fleas (or any other nasties, such as moths) that have got into woollies is to immerse the item completely in lukewarm water (around 30 degrees C). (You might as well add some wool wash to clean it at the same time.) Place something heavy, like a clean empty jar, on top of the item to make sure it is fully immersed.

Then rinse in lukewarm water, squeeze carefully, and roll in a towel to remove moisture, and dry away from direct heat. Wool dries pretty quickly so your hat will be ready to wear again soon!

If you don't want to wash the item, sealing it in a plastic bag (one of those with a "zipper" seal) and putting it in the freezer for a couple of days might work too, depending on how cold resistant the bugs are that you are trying to get rid of.

Cheers,
Sarah

What do you think?