What is hard water and soft water in dyeing?

The difference between soft water and hard water: 2113

Water is soft water and hard water. Water that does not contain or 5261 contains a small amount of calcium and 4102 magnesium ions is called soft 1653 water, otherwise it is called hard water. The hardness component of water, if caused by sodium bicarbonate or magnesium bicarbonate, is temporary hard water (boiled temporary hard water, decomposed sodium bicarbonate, precipitated by insoluble carbonate, and water turns from hard water to soft water); if caused by sulfate or chloride containing calcium and magnesium, it is permanent hard water, which cannot be removed after boiling. The above two kinds of hardness are collectively called total hardness. According to the total hardness value of water, the total hardness of 0-30ppm is called soft water, the total hardness of more than 60ppm is called hard water, the total hardness of high-quality drinking water is less than 25ppm, and the total hardness of high-quality soft water is less than 10ppm. In natural water, unpolluted rainwater and snow water far away from the city belong to soft water; spring water, stream water, river water and reservoir water mostly belong to temporary hard water, and some groundwater belongs to high hardness water.

When water droplets condense in the atmosphere, they dissolve carbon dioxide in the air to form carbonic acid. Carbonic acid eventually falls to the ground with the rain water, then seeps through the soil to reach the rock layer, dissolving lime (calcium carbonate and magnesium carbonate) to produce temporary hard water. In some areas, karst caves and hard water near them are formed in this way.