Superior RubyFluid Stainless Steel is a water-based, general purpose, inorganic-acid flux formulated for soldering stainless steel and other industrial metals. The flux contains Zinc Chloride and Hydrochloric Acid that make this flux active at room temperature where it begins to clean metals and remove oxides. The flux exerts a strong scavenging action to remove oxide coatings and other impurities from the metal surface to produce strong joints. Pre-cleaning is not necessary under most conditions.