Kester 5768 Bio-Kleen® is a highly concentrated liquid cleaner which is added to water to make a non-foaming solution for removing rosin flux residue. The alkaline chemicals in Kester 5768 react with rosin by a chemical conversion known as saponification to form soaps which are water-soluble. The resulting rosin soap and any water-soluble residue, such as activator salts, can then be rinsed away with water. Kester 5768 possesses enhanced ability to solubilize unsaponifiable material that is normally present in rosin and in additives used in some flux or solderpaste formulations. This assures excellent visual and ionic cleanliness of circuit boards after cleaning. A significant feature of this formulation is its stable composition during use at elevated temperatures such that a greatly increased operating life is achieved. This results in less frequent discharge of the wash tank for replacement with fresh solution and in a process cost reduction. Another special feature of Kester 5768 is that unlike other saponifier products which tend to mildly etch the solder surface, it leaves joints bright and shiny after cleaning. Kester 5768 eliminates the need for expensive, toxic and environmentally harmful solvents traditionally used for flux removal.