and liquid forms. The type of soap or detergent to be used depends on the fibre content, colour and the type of dirt on the fabric. Both soaps and detergents share a critical chemical property – they are surface–active agents or surfactants. In other words, they reduce the surface tension of water.
By reducing this effect water soaks more easily in clothes and removes stains and dirt faster. Surfactants and other ingredients in laundry detergents also work to keep the removed soils suspended in the wash water so they do not redeposit on to the clean fabrics. This prevents graying of fabrics. There are some differences in soaps and detergents.
Soaps possess a number of qualities that make them preferable to detergents. As mentioned earlier, they are natural products and less harmful to the skin and environment. Soaps are biodegradable and do not create pollution in our rivers and streams. On the other hand, soap is not effective in hard water, which results in wastage.
Another shortcoming of soap is that it is less powerful than synthetic detergent and tends to lose its cleaning power over time. An added benefit of detergent is that they can be specifically engineered for each cleaning task and for use in different types of washing machines. (iii) Methods of washing: Once the soap or detergent has emulsified the grease holding the dirt, it has to be held in suspension till it is rinsed out. Some parts of the fabric may have dirt, which is closely adhering to the fabric.
The methods employed for washing assist in these two tasks – disassociating the dirt adhering to the fabric and holding it in suspension. The method selected depends on the fibre content, the type of yarn and fabric construction and the size and weight of the article being washed. The methods of washing are classified as follows: Friction washing Kneading and squeezing Suction Washing by machines Let us now discuss these methods in detail. (a) Friction: This is the most commonly used method.
This method of cleaning is suitable for strong fabrics like cottons. Friction