Sour Alkalinity Neutralizer G.S.SOUR is an acidic powder to be added in the final rinse cycle to neutralize the alkalinity of the final rinse water. G.S.SOUR removes the dissolved rust in water which prevents the occurrence of the yellow color tinge on the white fabrics. G.S.SOUR leaves no alkaline residues on the fabrics, that is usually responsible for the unwanted gray tinge. There is no need to rinse after using G.S.SOUR.