LA-CO Regular Flux at MarkalCSP.com is available in a 4 oz. size with brush in cap. Flux Paste is a water soluble flux that meets industry standard ASTM B813 and won't leave residue in water piping. LA-CO's Regular Flux Paste is non-acid, non-toxic, and lead-free to eliminate safety concerns. Use in hot or cold climates on a variety of surfaces including copper, brass, galvanized iron, lead, zinc, tin, silver, nicke, mild steel and more.