How to Use Brass to Braze Copper
- 1). Clean the copper pieces free of dirt with a wire brush, then rub them free of oil using a clean rag saturated with degreasing solvent. Cleaning the metal removes the barrier dirt, rust and grease created between the base and filler metals, and it facilitates a strong bond.
- 2). Coat both pieces of copper with a layer of flux, a chemical paste, which prevents the formation of oxides on metal under heat. Flux also serves as a temperature indicator during brazing because it changes from a an opaque white paste to a clear liquid when the base metals are hot enough to braze.
- 3). Place the copper pieces on the firebrick, touching at the desired joint. Secure them in place using ceramic bricks or clamps. Assemble a flint striker and a brass filler rod next to a braze setup, then put on welding goggles and leather safety gloves.
- 4). Loosen the acetylene valve of an oxy-acetylene torch, and spark a flint striker in front of the nozzle to light the flame. Open the oxygen valve, and adjust the torch into an oxidizing flame --- a long, pointed flame consisting of a fuzzy, large blue outer cone and a pointed white inner cone. Wash the fuzzy outer cone of this flame over both sides of the joint evenly, watching the flux for changes as the copper heats.
- 5). Maintain the heat washing over the joint with one hand, and pick up the brass filler rod in the other when the flux liquifies. Touch the tip of the brass rod to one side of the joint, and point the torch and rod in the direction of the opposite side of the joint. Draw the rod along the joint as it melts, following by the torch. Remove the flame once the joint is complete. Shut off the oxygen valve, then shut off the acetylene valve.
- 6). Pick up the braised copper with metal tongs and drop it into a bucket of hot water to quench and crack the corrosive flux off the joint surface. Remove the copper from the water, then brush it vigorously with a wire brush to remove the last of the flux. Dry it with a clean rag.