INDIGO STYLES.
593
Sixth Style.—China (Indigo) Blues.
This style produces blue figures on a white ground, and is thereforethe reverse of Style V. A mixture containing indigo is printed on, andis then fixed by further treatment. The standard colour is made asfollows :—
No. i.—
Indigo . ». .. 45 lbs.
Iron liquor, at 24 0 Tw. . 9 gals.
Copperas. 18 lbs.
The mixture is ground in an indigo mill for three days, or till perfectly smoothand uniform, and is then further mixed with—
Gum Senegal water, at 6 lbs. per gal. gals.
The whole is then ground together for an hour, and the mill is finally washedout with r gal. or gals, of hot water, and the washings added. To reducethis standard to the shade desired, the following mixture, technically called“ China blue gum ” is used.
No. 2.—
Gum Senegal water, at 3 lbs. per gal. 2 gals.
Copperas . 4 lb.
Other standards are occasionally employed for the same purpose, such as:—
No. 3. Dark China Blue .—
Indigo . 12 lbs.
Iron liquor, at 22° Tw. . 2 4 S a l s *
Copperas. * 2 lbs.
Orpimeut . 3 »
The first two ingredients are ground together for about three days, theothers added, and the grinding continued for three days more. Gum water isthen added to the extent of 3 gals., and the grinding is resumed until thecolour is quite uniform. This standard is reduced to the shade required withgum water.
No. 4. Resist for China Blues .—
Sulphate of copper . 4 lbs.
Acetate of lead. 4 ,,
Water. 2 gals.
Flour . 5 lbs.
Boil, and when almost cold add—
Nitrate of copper in crystals. 10 lbs.
Lime-juice, at 36° Tw. 2 quarts.
(See also p. 484).
After the pieces have been printed and aged, the pieces are dipped alternatelyin lime-water and in a copperas vat, standing at i£° Tw. The time of eachdipping varies from fifteen to forty-five minutes, according to the shade required,and the number of dippings in each vat may be as low as four and as high aseight. They are next well rinsed in water, passed into sulphuric acid sours,the strength of which may run as high as g c or io° Tw., and left there till the
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