But the fastest colors known, both for light and for washing, are the modern Vat colors, many of which, once reduced, will dye in a lukewarm or even a cold dye-bath. While indigo, the type of these colors, and still most useful, gives a soft rather greyish shade of blue, more effective by itself than when mixed, there can be found among the Helindones, Thio indigoes, and the rest, a full palette of dyes which, properly mixed, will furnish any shade that may be desired.
The dyeing directions for batiked goods are the same as for ordinary calico. The materials, well wetted, are immersed, drained, wrung, and oxidized as usual. The wax is usually removed in one or more boiling soap baths, which help as well to set the color and to remove unattached dyestuff.
(b)Silk.—Silk, as in other processes, can be dyed in several different ways, according to the fastness to light and washing desired.
The easiest way, especially when trying to match shades, is to dye, with the Acid dyes, in a soap bath acidified with a little sulphuric, or, preferably, with acetic acid. These shades, however, while brilliant and fast to light, are not at all fast to washing, and so the wax must be removed later, with benzine or gasoline, and not with a hot soap bath.
The sulphur dyes, with a little glucose in the bath, and plenty of dyestuff, will give extremely fast colors on silk, but in most cases these shades will be too dull for proper effect. They can be greatly improved in color, though with some sacrifice of fastness, by topping them, without removing the wax, in a cold bath of Basic dyes, dissolved with a little acetic acid.
For extremely fast colors the Vat dyes can be used. Easier to apply, especially for rather light shades, are some of the Salt colors which, though they do not take as well on silk, in the cold, as they do on cotton will, nevertheless, color it well, with prolonged immersion, in a strong bath, in the presence of formic acid, and once on, will stand a very considerable amount of washing.
(c)Wool.—In case it is necessary to apply this process to wool, the latter will probably be dyed in the cold with Acid dyes, in the presence of some sodium sulphate (Glauber’s salt) and dilute sulphuric acid.
To make this color faster to washing, steaming, and the like, it is best, after dyeing, drying, and removing the wax with benzine, to boil the dyed goods for half an hour or more in a bath containing a little Glauber’s salt and dilute sulphuric acid, but no dyestuff.
(d)Leather.—As a rule, the Batiked leather should be dyed with Acid colors, acidified with acetic or formic acid, though they can be shaded afterwards, if desired, by staining with Basic colors.
After dyeing, the wax can be removed by benzine or, softened carefully by the cautious approach of a hot iron, can be incorporated with the polishing wax, used for rubbing down and finishing the surface.