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Sci Tech
How is dry cleaning of clothes done?
D. Gundu Rao, Chennai.
ANSWER: Dry cleaning means cleansing of textiles in non-aqueous (non-water) solvents. Highly vapourising organic solvents are commonly used as dry cleaning fluids. Many dirt, soil or stains producing substances on the fabric are organic in nature (sticky oily compounds). There is a common role in this regard that like dissolves like.
In wet cleaning, washing is achieved by the combined action of soap and water. Soap acts as a mediator between oil (present in dirt) and water, which are otherwise immiscible and non-reacting, in other words unlike in nature.
In dry cleaning, cleansing is achieved by the action of a solvent, which dissolves out the sticky matter due to its like nature. Dry cleaning fluids serve as a vehicle to carry away the soil. Camphene, naphtha, benzene, benzol, petrol, carbon tetrachloride, trichloroethylene and tetrachloroethylene are some of the frequently used dry cleaning fluids.
Dry cleaning neither changes nor alters the colour of the garment but retains all the finish and all of its new appearance, whereas the wet method makes the garment fade, flimsy, soft, loose and out of shape. Dry cleaned garments facilitate the subsequent pressing of many types of garments that are exceedingly difficult and tedious to press after they have been washed in water.
In spite of these advantages, dry cleaning is not widely undertaken, as the solvents used are costly and extremely combustible.
B. Narayanaswamy, Madurai.
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