This paste flux is fast acting; use sparingly. Apply with a standard flux brush. Solder will flow freely, forming a shiny rounded bead or joint. This lead-free flux eliminates the need for wire brushing, as it cuts through most oxidation. Works well on oxidized lead and works well with Lead Free solders. Compatible with copper foil, lead, zinc, brass, and copper came, and brass, zinc, and steel rebar. This is a special preparation in a light, easy to apply paste base. Works easily, even in cool weather and in chilly studios. Sold in a 2 oz. jar. Clean up with water or glass cleaner. Keep away from children; do not swallow.