Core's Colorfast Carpet & Upholstery Acid Rinse is a concentrated, biodegradable blend of unique mild acids that stabilize dyes and dye blockers. Specially formulated for color sensitive fabrics. Not only will it soften and condition your carpet, but it will also brighten your carpet fibers following a full carpet extraction or bonnet cleaning. The mild acid formula neutralizes pH to prevent browning, very similar to our Core Browning Treatment. Soil retardant additive enhances stain resistance.