After the weaving of a carpet is completed, it is taken down from the loom and washed so as to remove the fragments and small pieces of wool which have remained amidst the wefts and warps of the carpet after it has been clipped.This operation gives luster and shine to the fibres of the wool, and causes the pile to take its natural smooth direction and the design, too, looks more distinct.
This washing brings additional colours out of the skeins of wool giving a pleasant shade to the carpet. Carpet washing is a technical process. If not washed correctly the colours of different parts may bleed into each other. Expert craftsmen can eliminate the bleeding of colours by chemical substances, but it is best to test the fastness of the dyes, especially the red and dark blue colours before washing the carpet.
Most of the carpets with sharp colours are often washed chemically either in the special centres of the western countries or in Iran so as to produce mellow and soft colours acceptable to the demands of the dealers and consumers of those countries.By this method part of the dye substance used in the fibres is oxidised and a pleasant colour change occurs in the carpet. As an example we can mention the chemical process known as “gold washing” used to change the sharp red tones of certain carpets.