Dyestuff manufacturers explain the application of dyes.
1. Choose dyes according to the properties of the fibers. Because of the different properties of the fibers, it is necessary to choose suitable dyes when dyeing. For example, when cotton fibers are dyed, because its molecular structure contains many hydrophilic hydroxyl groups, which are easy to swell and absorb moisture. It can react with reactive groups and is alkali-resistant. Therefore, direct, reducing, sulfur, ice dyes and reactive dyes can be selected for dyeing. Polyester is hydrophobic and alkali-resistant at high temperature. In general, the above dyes should not be used, but disperse dyes should be chosen for dyeing.
2. Choosing the dyes according to the use of the dyed goods, the fastness requirements of the dyed products are different because of the different uses of the dyed goods. For example, the cloth used as curtains is not often washed, but often exposed to sunlight. Therefore, when dyeing, dyes with high light fastness should be selected. As underwear and light-colored fabrics for summer dyeing, dyes with high washing, sunshine and perspiration fastness should be chosen because of frequent washing and sunshine.
3. Choosing dyes according to the cost of dyes, we should consider not only the colour, light and fastness, but also the cost and supply of dyes and auxiliaries. If the price of dyestuffs is higher, we should try our best to substitute other dyestuffs which can dye the same effect, so as to reduce the production cost.
4. When choosing dyes for color matching, attention should be paid to their composition, solubility, color fastness and dyeing uptake when choosing dyes for color matching. Because of the different dyeing properties of various dyes, the dyeing effect is often affected by the different temperature, solubility and dye uptake. Therefore, dyes with similar properties must be selected for color matching, and the closer the better, which is conducive to the control of process conditions and the stability of dyeing quality.
5. Choosing dyes according to their dyeing mechanical properties. Because of different dyeing machines, the properties and requirements of dyes are also different. If used in jig dyeing, dyes with higher directness should be selected; if used in pad dyeing, dyes with lower directness should be selected, otherwise, products with shallow front and back and uneven color will be produced.