There are many types of dyes, but as far as the physical form of their products is concerned, they can be classified into solid, liquid and slurry. It can be further divided into:
Solid dyes--powder, granular, dust-free powder, lumps, flakes, short columns;
Liquid dyes --- water-soluble liquid, dispersion;
Mortar-like dye-solid / liquid mixture.
Dyes are organic compounds that often complete chemical reactions in the presence of liquids. For this reason, the world's first synthetic dyes were first sold in liquid form. Of course, the quality of the original dyes was much different from the present, and can only be considered The original form of liquid dyes today. About 20% of the products were liquid at the time, and these liquid dyes were mainly vat dyes and mordant dyes.