So Sour II is an alkaline break or heavily built detergent used in commercial multi-component system. It removes alkaline residues on fabrics which require use of a sour in the final rinse cycle for best results.  Additionally, iron or fine rust in laundry process water can cause spotting and discoloration.  Regular use of this product will counteract iron discoloration, as well as restoring natural fabric pH and increasing the effectiveness of softeners, starch and sizing used in the final rinse cycle. Features and benefits: Fast acting, labor saving, effective stain removal, easy to use, removes unsightly stains, saves linen costs, low odor and pleasant to use.