Woad returns in 'green' jeans

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WOAD, the dye used by Ancient Britons to paint themselves blue to frighten the Romans, may soon be making a peaceful comeback - in environmentally friendly jeans.

The cabbage-like plant, last grown on a large commercial scale more than a century ago, is undergoing EU-sponsored tests to see if it is feasible for farmers in Britain to cultivate it as a new crop for blue dye.

The experiments being carried out at the Long Ashton Arable Research Institute near Bristol, come amid concern about the increasing amount of synthetic dye being used. Around 800,000 tonnes of dye are produced worldwide each year, and one tenth of that for the colour indigo used in jeans.

One of the snags of using Woad as the Celts and medieval man found was that the process was extremely smelly, a problem the Long Ashton researchers have solved. Research Kerry Stocker said: "It was a smelly business. The leaves from the plant were mashed and formed into balls and on contact with the air the indigo would turn them blue. They would be left to dry for two or three months and the hard ball was then broken up, heated in water and allowed to ferment. It was then put in a vat with urine and wood ash and other materials and eventually you got a dye.

"We have developed a new process here where we simply put the leaves in hot water and the indigo is released into the water. It is a lot less smelly and we get a much purer dye" The station is also growing two other crops used by medieval man for colouring - weld, which produces a yellow dye, and madder, which gives a red.