Use of water softener is helpful to remove water hardness thus improving dye solubility and performance.

(1) For temporary hardness :

Temporary hardness is caused by calcium and/or magnesium carbonate. Temporary hardness can be removed simply by boiling the water or by taking the help of the following reactions:

Ca(HCO3)+Ca(OH)2→2CaCO3↓+2H2O

Mg(HCO3)2+2Ca(OH)2→2MgCO3+2H2O

MgCO3+Ca(OH)2→Mg(OH)2+CaCO3

(2) For permanent hardness :

Permanent hardness is caused by calcium or magnesium sulphate. Permanent hardness cannot be removed by boiling but can often be removed by chemical treatment .

CaSO4+Na2CO3→CaCO3+Na2SO4

MgSO4+Na2CO3→MgCO3+Na2SO4

MgCO3+Ca(OH)2→Mg(OH)2+CaCO3