Indigo Blue - Woad.

Scientific American 13, 28.9.1861

Blue has always bee na favorite color for army and navy cloth. The great demand for cloth of this color at the present time has had a wonderful effect upon the prices of indigo, the best qualities of Bengal and Guatemala having advanced about fifty cents per pound within two months. Blue or woolen cloths is dyed with woad and indigo in vats. All fine blue cloth is colored with these dye drugs, but a great deal of flannel and inferior cloth is colored blue with the ferro-cyanide of potash. The blue color is easily affected, and fades with solar light and exposure to the weather. Indigo and woad applied with alkaline solutions in vats produce fast colors, and no others are suitable for soldiers who are continually exposed to the weather.

The quantity of indigo in our market is very limited at present, and the import will be very small for a year to come, at least. The indigo crop was very light last year in Guatemala, and it was the same in India, owing to disturbances with the ryots in the indigo district.

Woad for coloring blue in the pastil vat was more extensively in use some years since than it is at present; its cultivation has therefore greatly decreased of late years. The hight prices of indigo may induce our farmers to enter upon its cultivation, as it produces a very fast and beautiful color on wool.