If you're facing spots that are tannin, salt or alkaline based, this is the spotter to use! TCU neutralizes alkaline salts from urine from Carpets, upholstery and mattresses. It also neutralizes residue from previous cleaning agents that are causing resoiling! It dissolves, neutralizes and dislodges alkaline salt residues that build up from pet accidents and other urine contamination for flushing and removal prior to the application of deodorizing treatment. It also contains special odor suppressants.