Scouring

Scouring

The desizing process is actually a destarching process because in this the starch present on warp yarns is liquefied by either hydrolytic or oxidative reaction and removed in subsequent washing step. But after desizing the fabric still contains fats and waxes (both natural as well as added), which adversely affect the absorbency of the fabric. These impurities are removed from the fabric by the process of “Scouring”.

Scouring

Thus the main purpose of scouring cotton fabric is to remove the natural as well as added impurities of essentially of hydrophobic nature as completely as possible and leave the fabric in highly absorptive state without undergoing a significant chemical or physical damage.

The scouring process is done by boiling the fabric in an alkali solution. The main processes occur during scouring are:

1. Saponification of oils present in the fibre.

2. Waxes and unsaponifiable material is removed by emulsification of the same.

3. Pectins are changed into their soluble salts of pectic acid.

4. Mineral matters are dissolved.                        

5. Proteins are hydrolysed into degradation soluble products.

6. Dirt or dust is removed and held in a stable suspension by the detergents present in the

    scouring bath.