Woad

Woad is derived from a plant, Isatis tinctoria, growing in the North

of France and in England. It was the only blue dye in the West before

Indigo was introduced from India. Since then woad has been little used

except as a fermenting agent for the Indigo vat. It dyes woollen cloth

a greenish colour which changes to a deep blue in the air. It is said

to be inferior in colour to indigo but the colour is much more

permanen . The leaves when cut are reduced to a paste, kept in heaps

for about fifteen days to ferment, and then are formed into balls

which are dried in the sun; these have a rather agreeable smell and

are of a violet colour. These balls are subjected to a further

fermentation of nine weeks before being used by the dyer. When woad is

now used it is always in combination with indigo, to improve the

colour. Even by itself, however, it yields a good and very permanent

blue.



It is not now known how the ancients prepared the blue dye, but it has

been stated (Dr. Plowright) that woad leaves when covered with boiling

water, weighted down for half-an-hour, the water then poured off

treated with caustic potash and subsequently with hydrochloric acid,

yield a good indigo blue. If the time of infusion be increased, greens

and browns are obtained. It is supposed that woad was "vitrum" the dye

with which Caesar said almost all the Britons stained their bodies. It

is said to grow near Tewkesbury, also Banbury. It was cultivated till

quite lately in Lincolnshire. There were four farms in 1896; one at

Parson Drove, near Wisbech, two farms at Holbeach, and one near

Boston. Indigo has quite superseded it in commerce.