Why use soft water for washing linen?

Everyone is familiar with linen washing. Why do we use soft water when we wash linen? Is there any significance here? Generally speaking, the suspended solids, colloids, dissolved oxygen or free carbon dioxide in the water will not have much effect on the washing, of course, if the suspended solids become cloudy, it is another matter. The impact on washing quality is more due to ionic impurities in the water. It is well known that after the water rich in carbon dioxide penetrates into the rock, it will react with calcium carbonate or magnesium carbonate in the rock to form magnesium bicarbonate or calcium bicarbonate. Dissolving inorganic salts in water will produce ionized impurities, which are mainly composed of sodium, calcium, magnesium, potassium and other ions, as well as a small amount of iron ions, which are all positive. Of course, it does not mean that the impurities in the water are all positive, and there are also anions, such as chloride ions. These impurities will form scale when heated during the washing process, and after the use of hotel washing equipment for linen washing at a high temperature of 140-160 °C in the ironing machine. The reason why raw water cannot be used is because the water is not pure, especially the high content of multivalent calcium ions and magnesium ions in water. Usually the sum of calcium and magnesium ions in water is called the total hardness of water. After the calcium and magnesium ions in the water are removed by some methods, the water that will not cause secondary pollution to the linen is called soft water. This process is the softening of the water! When the water is hotter, some white precipitates come out - calcium carbonate and magnesium carbonate. After precipitation, the calcium and magnesium ions in the water will be reduced, and the water will become soft. We call the hardness of this water temporary hardness. Because the precipitation is carbonate, also called carbonate hardness. But this time it is only slightly softened, there are still calcium and magnesium ions in the water, and the water still has hardness. This hardness is called sexual hardness, also called non-carbonate hardness. Regardless of the composition of scale, since scale can be formed, the linen will be polluted. There are impurities in the water, which will affect the washing. It can even be said that no matter how hard it is, it is difficult to wash the sheets and duvet covers very well, not to mention the towels.