After reading this article you will learn about the quality of water suitable for laundry work.
The presence of some of the important dissolved impurities in water makes it unsuitable for washing of clothes. These dissolved impurities are compounds of calcium, magnesium and iron salts in water. They cause hardness in water which is called hard water. Hardness in water is the power to kill soap.
Sufficient lather cannot be formed when soap is used for cleaning of fabric. When soap is used in hard water, the salts of calcium and magnesium react with the soap to form an insoluble curdling substance known as scum which has no cleansing power. This reaction kills the soaps and makes it useless for washing of fabrics. Larger quantities of soap have to be used in order to produce lather.
Types of hardness:
For laundry purposes, hardness of water is measured in degrees. The number of degrees of hardness in water varies with its mineral content.
There are two types of hardness in water:
(a) Temporary Hardness:
When hardness of water is due to the presence of calcium and magnesium bicarbonates it is called as Temporary hard water. The presence of bicarbonates is due to the action of the carbonic acid with the insoluble calcium carbonate.
On boiling, these soluble bicarbonates are changed into insoluble carbonates. These are separated from water in the form of sediment. The accumulation of this sediment is responsible for the scale or fur which forms in kettles and pans where hard water is used.
(b) Permanent Hardness:
This hardness is due to the presence of sulphates of calcium and magnesium, chlorides and nitrates. The hardening salts being soluble in pure water make it more persistent than temporary hardness. Permanent hardness can be removed by distillation process or by using certain chemicals.
Soft water is most suitable for drinking bathing and washing purposes. It is considered as, pure water because it is free from all types of dissolved impurities like calcium and magnesium salts. Soft water contains less than 3 degree of hardness. Sufficient foam or lather is formed from this water when soap is added. It is the best water from laundry point of view. This water washes the fabric as well as saves time and soap.