Oxiclean Series Black/Brown Silver Brazing Fluxes Are Formulated Using a Balance Of Chemical Ingredients And Antioxidents By Chemical Reactions And Not Onlu By Mixing of Different Miner Al Salts Amoung Simples And Complex Potassium Fluorine & Boron Compounds. A special purpose flux used with stainless steel, tungsten carbides, chromium carbides & refectory metals. Wide active range & perfect wetting with control spread. Colour dark brown. Contains elemental boron metal powder.