3. Vat dyes:
The dissolution process of vat dye is a reduction reaction process. When dissolving, the dissolution temperature should be determined according to the reducing conditions of the reducing agent used. For example, the commonly used reducing agent for vat dyes is insurance powder. The best use temperature in the solution is 60 ℃. Excessive temperature will cause a large amount of decomposition of insurance powder.
(1) Full bath method:
Put the dye in the dyeing cup, add red oil and a small amount of warm soft water to mix thoroughly, then add the specified amount of caustic soda and insurance powder, then add soft water to the required bath volume, and reduce at 55 ℃.
(2) Dry cylinder method:
Put the dye into the dyeing cup, add red oil and a small amount of warm soft water to mix thoroughly, then add two thirds of the amount of caustic soda and insurance powder, so that the amount of dye liquor is one third of the total, according to the reducing conditions of the reducing agent To determine the dissolution temperature. Add the remaining caustic soda and insurance powder to the dye cup, and add soft water to the required bath volume.
4. Sulfur dyes:
Accurately weigh the required amount of dye in a beaker, adjust it to a slurry with cold and soft water, then add the dissolved sodium sulfide dye solution in advance, and boil for 10 minutes. Dilute by heating soft water, add soft water to the specified volume after cooling.