Fluxrite is a mid to dark brown, soft paste, designed for engineering and sheet metal work. The flux is active and contains zinc chloride and is suitable for soldering many metals including copper, brass and mild steel. This all-purpose paste flux has been used successfully in gas systems for many years where professional application is essential. Fluxrite is WRAS approved for use in both hot and cold water systems and is also listed in the UK Water Fittings and Material Directory. This product has a shelf life of 3 years from the date of manufacture. WRAS Approval No 2101538.