The success depends upon the composition of the color printed, and above all upon the strength of the vats of immersion and the duration of the treatment.
The operator uses six vats,—for instance, two lime vats, provided each with 12 kilograms of lime; a copperas vat at 70 Beaumé; a caustic soda vat marking 140 Beaumé; a sulphuric acid vat with 500 grammes of acid (par mesure d’eau); and finally a vat of pure water.
The receipts for printing are:—
| 1. THE BLUE PREPARATION. | ||
| Ground indigo | 4 | kilograms. |
| Acetate of iron | 10 | litres. |
| Sulphate of iron | 1 | kilogram. |
| Water | 10 | litres. |
| Gum Senegal | 6 | kilograms. |
Pass through a sieve; leave some time at rest, and stir whenever used. Caraccas indigo is preferred because it can be broken into a finer powder and gives a finer paste.
| 2. COLORS FOR ROLLER PRINTING NOS. 1, 2, 3, 4. | |
| The blue preparation above | 1, 1, 3, 4. |
| Acetate of iron containing 700 grammes of gum per litre | 2, 1½, ½, ½. |
| Gum water at 600 grammes per litre | 16, 2½, ½, ½. |
These proportions can be varied according to the tint desired.
The piece is treated a quarter of an hour in the first lime vat by giving it a light movement from above to below; it is left a quarter of an hour in repose in the sulphate of lime vat; a quarter of an hour in the second lime vat; a quarter of an hour in the copperas vat; five minutes in the caustic soda; half an hour in the sulphuric acid, and then thoroughly rinsed.
To each lime vat there is given 2 kilograms of lime per piece of cloth. To the vitriol vat there is added 50 kilograms of sulphate of iron for each dozen pieces. The soda vat is renewed after 5 pieces by the addition of 12 kilograms of salt of soda, which has first been made caustic. The acid vat receives 25 kilograms of acid after 5 pieces, and ought to be renewed whenever it becomes saline. The other vats must be cleared out whenever the deposit becomes too great for success.
M. Ed. Schwartz recommends as important conditions, (1) the perfect causticity of the tissue, and an average strength of 140 Beaumé; (2) the neutrality of the sulphate of lime vat. For this end old iron should be boiled in it.