1, natural or man made fibres woven fabrics, containing various impurity:
1) natural impurities: some of these impurities is a symbiosis of the fibre itself, such as cotton seed shell, wax, pectin, nitrogen-containing substances, pigments, etc;
2) artificial impurities: some of them are in the former procedure (spinning, spinning, weaving) because of added processing needs, such as paste, oil, etc.
2, can be carried out smoothly in order to make the fabric or yarn dyeing, printing and finishing, are semi-finished products that meet quality requirements, these impurities must be removed, this process is known as pre-treatment.
3, the former including desizing, scouring and bleaching, mercerization process. In these processes, in addition to joining a variety of inorganic substances (such as acid, alkali and hydrogen peroxide), often also need to add some auxiliary chemicals to help increase efficiency, improve quality or energy conservation.