On the Blue Colour in Woad

Abstract

THE old East Anglian proverb, “As blue as wad,” occurs to one visiting the Woad Mill described by Mr. Darwin in NATURE, in 1896 (vol. lv. p. 36), as evidence that woad once yielded a blue dye. As a natural sequence one wonders what sort of blue it was and how it was obtained. A somewhat extended series of inquiries amongst those engaged in the woad industry, amongst those who have written on woad, and amongst botanical, archæological and chemical friends, failed for a long time to elicit the desired information. Curious as it may appear, an appeal to botanical and chemical works, to dictionaries and encyclopaedias was equally unsuccessful. The last-named were pretty uniform in their statements about woad, in that it “was formerly used for dyeing blue, but is now superseded by indigo.” Many of the books give an account of the woad-vat in which the manufactured woad is used with bran and lime as a ferment to change the insoluble indigo-blue into the soluble indigo-white; but they give no clue as to how woad may be used as a blue dye alone. It has been said that the blueness of woad was more or less a myth, and even if it ever possessed this quality it has long since been lost by continued cultivation.