Equal quantities of these two liquors are used in making the developing bath.
Of late years, under the names of Azophor red P N, Nitrazol C, Nitrosamine, etc., there has been offered to dyers preparations of diazotised paranitroaniline in the form of a powder or paste, readily soluble in water, that will keep in a
FIG. 29—Developing Machine for Paranitroaniline Red.
cool and dry place for any reasonable length of time. These are prepared in various ways, and to any dyer who does not
want the trouble of diazotising the paranitroaniline they offer some advantages. They produce a red equal in every respect to that obtained from paranitroaniline. The following details show the method to be followed with some of these products, others are very similar to make the developing baths.
Paranitroaniline Red with Nitrazol C.—Dissolve 25 lb. Nitrazol C in 12 gallons of cold water with constant stirring, then add sufficient cold water to make 37 gallons. In another vessel dissolve 11 lb. of acetate of soda in 5½ gallons water, then add 1½ gallons caustic soda, 36° Tw., mixed with 5½ gallons water. The developing bath is made by mixing both these solutions. It will suffice for both yarn and piece goods.
Paranitroaniline Red with Azophor Red P N.—Dissolve 5½ lb. of Azophor red P N in 4 gallons of water—it dissolves almost completely but usually a few particles of a flocculent character remain undissolved, these can be removed; 2¼ gallons of caustic soda lye of 36° Tw. are diluted with water to 10 gallons, and this is added with constant stirring to the azophor red P N solution. When all is mixed and a clear solution obtained, the developing bath is ready for use, and is used in the same way as the paranitroaniline bath.
Metanitroaniline Orange.—This orange is produced in the same way as the paranitroaniline red, using metanitroaniline or Azophor orange M N in place of the paranitroaniline or the Azophor red P N given for the red. The quantities of all the materials used are identical.