The dyestuffs used in leather industry usually use dyes, and special dyes tend to develop diphenylamine substitutes, metal complex dyes and reactive dyes.

Special dyes for leather can be well combined with leather fibers. They have good fastness to light, wash and rub, good levelling characteristics, and safety and innocuity.

In contrast, there are many kinds of foreign dyes specially used for leather, such as Germany Bayer, Basf Inc and Swiss Santos company have dozens of special dyes for leather.

Since 1995, the German government banned the production and sale of textiles and leather products that produce carcinogenic aromatic amine azo dyes, which has greatly shocked China's dyestuff industry and leather industry.

The dyes commonly used in leather dyeing are direct and acid dyes. Many banned dyes are commonly used dyes for leather dyeing, such as direct black BN and acid scarlet GR. Therefore, the development of special dyes for leather has become an urgent task.

On the other hand, from the form of dyes, solid dyes are liable to cause inaccurate weighing due to their hygroscopicity, and when exposed to use, they will cause contamination and harm to the environment. Liquid dyes are not only convenient for use, but also have good levelling properties and are not sensitive to pH value, liquid ratio and temperature, so liquid dyes have become one of the development trends of specialty dyes for leather.

For example, Sellasat, a new liquid dyestuff series introduced by Ciba Jiaji company, has been widely used in tanneries.