In the calico print-works the madder goods are passed through a bran bath first, immediately after dyeing ; next, after several days exposure to the air, when the dun dye has become oxidized, and is more easily removed. An addi tion of chalk, on the principles explained above, is sometimes useful in the madder bath. If bran be added to the madder bath, the color becomes much lighter, and of an agreeable shade. Sometimes bran-water is added to the madder bath, instead of bran.
The ordinary madder-red dye is given in the following way :—The yarn, or cloth, is put into a very weak alkaline bath, at the boiling temperature, then washed, dried, and galled ; or, when the calico is to be printed, for this bath may be substituted one of cow-dung, subse quent exposure to the air for a day or two, and immersion in very dilute sul phuric acid. In this way the stuff be comes opened, and takes and retains the color better. After the galling, the goods are dried, and alumed twice ; then dried, rinsed, and passed through the madder bath. This is composed of three-fourths of a pound of good madder for every pound weight of the goods. The bath is slowly raised to the boiling point in the course of 50 or 60 minutes, more or less, according to the shade of color wished for. When the boiling has continued for a few minutes, the stuff is taken out, washed slightly, and dried a second time in the same manner, and with as much madder. It is then washed and dried, or passed through a hot soap-bath, which carries off the fawn-colored particles. Other dyes, likewise, are added to the madder-bath, to obtain other shades of color ,• for instance, a decoction of fustic, weld,Iog-wood, quercitron, knoppern, the mordants being modified accordingly.
Holterhoff prescribes, for ordinary madder-red, the following proportions : 20 lbs. of cotton-varn, 14 lbs. of Dutch madder, 3 lbs. of gall-nuts, 5 lbs. of alum ; to which are added, first 14 lb. of acetate of lead, and, subsequently, # lb. of chalk. When bran is added to the madder-bath, the color becomes much lighter, and of a more agreeable tint.— Adrianople madder-red is given by many distinct operations. The first consists in cleansing. or scouring the goods by alka line baths, after which they are steeped in oily liquors, brought to a creamy state by a little carbonate of soda solution. Infusion of sheeps'-dung is often used as an intermediate, or secondary steep.
The operation of oiling, with much man ual labor, and then removing the super fluous or loosely-adhering oil, with an alkaline bath, is repeated two or three times, taking care to dry hard after eaeh process. Then follows the galling, alum maddering, and brightening, for re moving the dun-colored principle, by boiling at an elevated temperature, with alkaline liquids and soap. The whole is often concluded with a rosing by salt of tin.
According to the latest improvement of the French dyers, each of the four pro cesses of oiling, mordanting, dyeing, and brightening differs, in some respects, from the above.
1. Their first step is boiling the cloth for four hours, in water containing one pound of soap for every four pieces. Their saponaceous bath of a creamy aspect is used at a temperature of 75° F. ; and it is applied by the padding machine 6 times, with the grassing and drying alterations. In winter, when tho goods cannot be exposed on the grass, no less than 12 alternations of the saponaceous or white bath are employed, and 8 in spring. They consider the action of the sun beams to aid greatly in brightening this dye; but at midsummer, if it be con tinued more than 4 hours, the scarlet color produced begins to be impaired.
They conceive that the oiling opera tion impregnates the fibres with super margarate of potash or soda, insoluble salts which attack and condense the alu mina, and the red coloring particles of the madder, so firmly that they can resist the clearing boil.
2. Their second step, the mordanting, consists first in padding the pieces through a decoction of galls mixed with a solution of equal weight of alum ; and after drying in the hot flue, &o., again padding them in a solution of an acetate of alumina, made by decomposing a sol ution of 16 lbs. of alum with 16 lbs. of acetate of lead, for 6 pieces of cloth, each 32 ounce long.
8. The maddering is given at two suc cessive operations ; with 4 pounds of Avignon madder per piece at each 4. The brightening is performed by a 12 hours' boil in water with soda crystals, soap, and salt of tin;' and the meow by a 10 hours' boil with soap and salt of tin. Occasionally, the goods are passed through a weak solution of chloride of potash. When the red has too much of a crimson cast, the pieces are exposed for two clays on the grass, which gives them a bright scarlet tint.