Winter washday reverie

By Associate Professor Allan Blackman

This article was orignally published in the Otago Daily Times on Saturday 10 May 2008.

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After such a wonderful summer, it’s probably only fair that we’ve had a few days of less than clement weather recently. Winter is well and truly on the way, and with it comes those frustrating days when you just cannot get things dry on the clothesline – indeed, those of you in Central Otago probably have more luck freeze drying your clothes at this time of year. Wouldn’t it be nice if we didn’t have to worry about getting the washing dry – indeed, wouldn’t it be nice if we didn’t have to do any washing at all? Think of all the time, electricity and money that would be saved. But, on the other hand, our clothes would be covered in stains and they’d probably smell a little. Wouldn’t they?

Well, not necessarily. All we need are clothes that can clean themselves without having to be washed. And this is not as far-fetched as it might sound. Researchers in Australia and Hong Kong have recently published results of their studies of self-cleaning wool. They showed that when the specially modified wool was stained with red wine and then exposed to simulated sunlight for 20 hours, the stains disappeared almost completely. And, thanks to Chemistry, we don’t have to breed genetically modified sheep to obtain this wonder wool. It is made simply by impregnating normal wool with tiny crystals of titanium dioxide, a compound we all encounter (probably unknowingly) every day through its use as a whitener in paper and plastics. These tiny crystals are called nanoparticles, and have diameters of 4 to 5 millionths of a millimetre. When they absorb ultraviolet light from the sun, they facilitate the formation of extraordinarily reactive chemical species called hydroxyl radicals, which can rapidly degrade highly coloured and/or odoured molecules while hopefully leaving the wool fibres untouched. So potentially, you need never wash your clothes again – just wear them in the sunlight and they’ll be as good as new. I do, however, see one fairly obvious drawback to this – it’s going to be rather difficult to get your underwear clean without exposing yourself to a few disapproving glances.

There’s lots of money to be made in keeping clothes clean, and this is illustrated by a famous (well, famous amongst chemists anyway) incident from Europe in 1994. Unilever released a new product called “Persil Power”, a laundry powder that reputedly cleaned clothes more efficiently than any other, thanks to the presence of a new manganese-based catalyst. However, it so happened that not only did Persil Power eat dirt and stains, it also ate the clothes as well, a fact that the competing company Proctor and Gamble took great delight in pointing out. This little escapade cost Unilever an awful lot of money – in addition to withdrawing the product, losing a significant market share and writing off £57 million in 1995, it was estimated that over £200 million was spent in development, marketing and building three new plants to produce the powder. You’d imagine there may have been a few redundancies in the quality control department at Unilever in the mid-nineties.

So I think I’ll stick to the tried and true method of washing my clothes and hanging them out to dry, even if it might take a while. For it’s only about 6 weeks until the shortest day, and the weather always gets warmer after that. Doesn’t it?