General Indicators And Classification of Water Used in Printing And Dyeing

The quality of water used in printing and dyeing directly affects the quality of printing and dyeing.

General Indicators
1. Hardness
Hardness is the first main indicator of water used in printing and dyeing, which usually refers to the total amount of Ca²⁺ and Mg²⁺ ions in water. Generally, the hardness of water is tested by titration. Hardness test strip is also used, which is faster.

2. Turbidity
It reflects the turbidity of water. That is the amount of insoluble suspended solids in the water. It can be quickly tested by turbidity meter.

3. Chroma
Chroma reflects the amount of colored material in water, which can be tested by platinum-cobalt standard colorimetry.

4. Specific conductance
Specific conductance reflects the amount of electrolytes in water. Generally, the higher the salt content is, the higher the specific conductance will be. It can be tested by electrical conductivity meter.

Classification of Water Used in Printing And Dyeing
1. Underground water (Well water):
Underground water is one of the earliest sources of water used for printing and dyeing. But with the overuse of underground water resources in recent years, the use of underground water has been banned in many places. Underground water in different places is different in features. The hardness of underground water in some areas is very low. While in some areas, the content of iron ions of underground water is very high.

2. Tap water
Nowadays, in many areas, printing and dyeing factories are using tap water. There should be considered the amount of chlorine remaining in the water. It is because that tap water is disinfected by chlorine. And the residual chlorine in the water will affect some dyes or auxiliaries.

3. River water
It is universal that river water is used for printing and dyeing in the southern region where there is more precipitation. River water hardness is lower. The water quality changes obviously which is influenced by different seasons. So it is required to adjust the process according to different seasons.

4. Condensate water
To save water, now most of the steam condensation water in the factory (including dyeing heating and drying steam, etc.) is recycled for printing and dyeing water. It has very low hardness and has a certain temperature. It should be noted the pH value of condensate water. The pH value of condensate water in some dyeing mills is acidic.

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