iron powder and magnets may come to the rescue of birds caught in oil spills. John Orbell and his colleagues at the Victoria University of Technology in Melbourne, Australia, said the iron is sprinkled on the affected areas of the birds and combing the feathers with a magnet removes oil as well as the iron. Unlike detergents, the technique removes oil without destroying the waterproof properties of the feathers. "Iron powder is cheap and plentiful, and nontoxic,' says Orbell.

The technique was tested on duck feathers coated with different grades of oil. The first coating and combing removed 88 per cent of light crude oils from the feathers and over 60 per cent of more viscous types. In all tests, 97 per cent of the contaminants were removed after the procedure was repeated 10 times. Orbell's team examined feathers cleaned with iron powder under a microscope and found that their tiny barbules were neatly aligned, as they should be. Water rolled off the feathers, showing that they had kept their water-repellent quality. In contrast, the barbules of feathers cleaned with detergents were entangled, disrupting the microstructure and impairing the feathers' ability to shrug off water.