After washing, work the cotton in a cold infusion of 30% to 40% of Sumach, or its equivalent in other tannin matter[15] (ground gall nuts, myrobalans, etc.) and let steep over-night. Squeeze out and without washing pass through a bath containing a diluted solution of lime water, or soda. Work in a cold solution of copperas for ½ hour, then back into the soda for a ¼ hour at a temperature of 50° to 60°C. Then wash. Dye in a freshly made bath of logwood with a small proportion of old Fustic or Quercitron Bark. The cotton is introduced into the cold dye liquor and the temperature gradually raised to boiling. Boil for ½ an hour. After dyeing, the cotton should be passed through a warm solution of Bichromate of Potash. (5 grains per litre). It is then washed and worked in a warm solution of soap and dried. More Fustic makes a greener black.
When catechu is the tanning matter employed, the cotton should be worked in a boiling decoction of it and allowed to steep till cold.
2). Grey Drab for Wool.
(10 lbs.) Dissolve ½ oz. Bichromate of Potash in water, and then boil for ½ hour; lift the wool and add 1 oz. logwood: boil for ½ hour. Lift out, wash and dry.
3). Logwood Grey on Cotton.
The cotton is worked in a weak decoction of logwood at 40° to 50°C., and then in a separate bath containing a weak solution of ferrous sulphate or Bichromate of Potash. Wash.
4). Green Black for Wool.—
Mordant wool with 3% Bichromate of Potash and 1% Sulphuric acid (or 4% Tartar) for 1 to 1½ hours. Then wash and dye with 35% to 50% of Logwood. This gives a blue black. It is greened by adding 5% old Fustic to the dye bath. The more Fustic the greener the black becomes. If 3% to 4% alum is added to the mordanting bath, a still greener shade is obtained. Sulphuric acid in the mordant produces a dead looking blue black. Tartar yields a bright bluish black.
5). Logwood Blue for Wool.
Mordant the wool for 1 to 1½ hours at 100°C., with 4% alum and 4 to 5% cream of Tartar. Wash well and dye for 1 to 1½ hours at boiling point with 15 to 30% logwood and 2 to 3% chalk. This colour is not very fast, but can be made faster by adding 1 to 3% bichromate of potash and 1% sulphuric acid. The brightest logwood blues are obtained by dyeing just below boiling point. Long boiling dulls the colour.