The Natural Dye Blues - Indigo, Woad and Logwood

INDIGO

Indigo is likely the most well known natural dye and refers to the blue matter extracted indigo bearing plants, most commonly from Indigofera tinctoria which originates in Asia, India and South America. It reaches the market in a fine powder or pressed block which is insoluble in water. World consumption of indigo in the 1800s was very large, so in 1866 a German chemist named Adolph von Baeyer began his studies of the pigment and eventually elucidated its chemical structure so that it could be synthesized commercially. At the end of the 19th century, Germany was able to produce synthetic indigotine cheaper than the natural dyestuff, and thus Germany took charge of supplying indigo.

Indigo produces a colorless glucose based substance called indican. Fermentation breaks this glucose down to indigotin which is insoluble in water. It needs to be chemically reduced to be used as a natural dye. In the reduced form, fiber is immersed and when removed and allowed to oxidize, turns back to it's blue colour. This process is referred to as vat dyeing. The blue dye from Blue Castle Fiber Arts as well as other natural indigo extracts on the market, don't require this method and are easier to use. However, it is an interesting process and it doesn't require other mordants. Precise instructions and supplies are available from:
Aurora Silk
Dharma Trading Co. and
Maiwa Handprints


WOAD

Woad is derived from a plant, Isatis tinctoria, growing in the North of France and in England. The blue pigment in woad is the same as in indigo (Indigofera tinctoria) dye, but it is less concentrated. It was the only blue natural dye in the West before Indigo was introduced from India. 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 permanent. The fresh, young 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 balls are subjected to a further fermentation of nine weeks before being used by the dyer. There has to be a breakdown of indican, a sugar-bearing molecule, to the dyestuff indigotine. When woad is now used it is often in combination with indigo, to improve the colour. Even by itself, however, it yields a good and very permanent blue.


LOGWOOD
(Bois de Campeche, Campeachy Wood)

Logwood is a natural dye wood from Central America, used for producing blues and purples on wool, black on cotton and wool, and black and violet on silk. It is called by old dyers one of the Lesser Dyes because the colour was said to lose all its brightness when exposed to the air. But with proper mordants and with careful dyeing this natural dye can produce fast and good colours. The logwood chips should be put in a bag and boiled for 20 minutes to 1/2 an hour, just before using.

RECIPES for DYEING with LOGWOOD

BLACK
Mordant the wool for 1 to 1-1/2 hours with 3 per cent Chrome and 1 per cent Sulphuric Acid. Wash and dye in separate bath for 1 to 1-1/2 hours with 50 per cent Logwood. This gives a blue black.

A dead black is obtained by adding 5 per cent Fustic to the dye bath.

A green black by adding more fustic. Also by adding 3 to 4 per cent Alum to the mordanting bath a still greener shade can be obtained.

A violet black is produced by adding 2 per cent Stannous Chloride (tin) to the dye bath and continue boiling for 20 minutes.

LAVENDER
Mordant with 3 per cent Bichromate of Potash* for 45 minutes and wash. Dye with 2 per cent madder, 1 per cent logwood. Enter the wool, raise to the boil and boil for 45 minutes. The proportion of logwood to madder can be so adjusted as to give various shades of claret to purple.

A FAST LOGWOOD BLUE
(Highland recipe.) Mordant with 3 per cent Bichromate of Potash* and boil wool in it for 1-1/2 hours. Wash and dry wool. Make a bath of 15 to 20 per cent logwood with about 3 per cent chalk added to it. Boil the wool for 1 hour, wash and dry. The wool can be greened by steeping it all night in a hot solution of heather till the desired tint is obtained.

DARK RED PURPLE WITH LOGWOOD
Mordant with 25 per cent alum and 1 per cent cream of tartar for 1 hour. Let cool in the mordant, then wring out and putaway for 4 to 5 days.

Dye with 60 per cent logwood and 25 per cent madder. Boil up the logwood and madder in a separate bath and pour through a sieve into the dye bath. Enter the wool when warm and bring to the boil. Boil from 1/2 hour to 1-1/2 hours. Wash thoroughly in soft water.

PURPLE

Mordant wool with 25% alum and 3% tartar for one hour; wring out and put away in a bag for some days. Dye with 1/4 lb. logwood for 1 hour.



* Although Bichromate of Potash or Chrome is used in small amounts, it is considered a toxic substance.

See Natural Dyes from Blue Castle Fiber Arts