Stain Drop No1 C005506-CS20B2 2 lb Container 12 per case. Stain Drop No1 is formulated to effectively remove iron (rust) stains and discoloration. Sometimes deposited iron can complex with other metals forming a "protective" scale that needs to be removed prior to iron stain removal. Regardless of the type of iron staining present, Stain Drop No1 will aid to remove unsightly staining from all surfaces.