The quality of washing water is standardized to a certain extent.
The quality standard of water is determined according to the content of impurities in the water.
Due to the wide distribution of calcium and magnesium salts in nature, calcium and magnesium salts become the main components of hardness.
The total hardness of ordinary water is the sum of the concentration of calcium and magnesium ions in water.
The hardness unit is the German degree, which means that 100 parts of water contains one part of calcium carbonate, equivalent to one part of German degree.
Now we use mmol/L as a unit of hard water.
1 German degree is equal to 0.357mmol/L.
Due to the variety and quantity of impurities in water, water is generally divided into hard water and soft water.
Water with hardness above 2.9mmol/L (8.
German degree) is called hard water.
3. Disadvantages of hard water cleaning: when washing clothes with soap with high content of hard water and calcium and magnesium ions, the combination of calcium and magnesium ions in hard water consumed 30% of the ingredients in the soap solution.
Calcium-magnesium compound soap is a kind of insoluble viscous substance in water.
Clothes get dirty and hard to wash off.
If worn, the clothes will turn white, yellow and crisp.
Therefore, hard water is not suitable for washing clothes.
The advantage of soft water cleaning is that there are no heavy metal ions such as calcium and magnesium in soft water, which will not react with detergent and produce insoluble adhesion.
As a result, it saves a lot of detergent, softener and bleach, while removing stains on clothing and avoiding yellow-haired hardwear.