The cause may be poorly heat set dye from the manufacturer of the fabric or rug, or excess dyes used to create deeper richer colors, of poor quality dyes. The most common place for this to occur is in either oriental rugs or in jacquard type fabrics, where yarns that are dyed in different colors contact each other.
Acid sets dyes and alkaline releases dye.
Dye-Loc , the Bridgepoint exclusive product, is a different type of product and works differently from the acid chemicals. Rinse thoroughly with another solution of dilute Dye-Loc . The exact formulas for this type of cleaning is found in the Bridgepoint product catalog in the carpet or upholstery formula section.