By coupling, chroming or developing, the direct blacks can be made to give full, deep and fast blacks, and examples of their use in this manner will be found in following sections.
By using all the direct blacks in proportions varying from ¼ to 1 per cent. of dye-stuff to the weight of the cotton they give greys of various tints and depths; a few examples of such greys will now be given.
Blue Grey.—Prepare the dye-bath with ½ lb. Oxydiamine black A, 1 lb. soda, 10 lb. Glauber's salt. Dye at the boil for one hour.
Bright Grey.—Prepare a dye-bath with 4½ oz. Azo mauve A M, 1½ oz. Direct yellow G, 3 lb. soda, 15 lb. common salt.
Silver Grey.—Prepare the dye-bath with ½ oz. Neutral grey G, 10 lb. sulphate of soda. Work at the boil to shade, then lift, wash and dry.
Slate.—Dye in a bath with ½ lb. Diamine black B H, 3 oz. Diamine bronze G, 15 lb. Glauber's salt at the boil for three-quarters of an hour.
Bronze Grey.—Prepare a dye-bath with ½ lb. Diamine bronze G, 15 lb. Glauber's salt, 3 lb. soap. Enter at about 160° F., raise to boil and work for one hour; lift, wash and dry.
Dark Slate.—Prepare a dye-bath with 10 lb. Glauber's salt, 1½ lb. soap, 1 lb. Diamine black R O, 2 lb. Cotton brown N. Heat to about 150° F. Enter the goods, work for a short time, then raise to the boil and work for one hour; lift, wash and dry.
Green Grey.—Prepare a dye-bath with 10 lb. Glauber's salt, 1 lb. Diamine black R O, ¾ oz. Thioflavine S. Enter at from 150° Tw. to 180° F., raise to boil and dye for one hour; wash and dry.