Successful Brazing Steps-Step 6: Clean The Brazed Joint

Clean the brazed joint.
After you braze the assembly, clean it. Because most brazing fluxes are corrosive, cleaning is essential. Cleaning usually is a two-step operation:
1. Remove the flux residues.
2. Remove any oxide scale formed during the brazing process by pickling.
Because most brazing fluxes are water-soluble, you can remove residues by quenching the assembly in hot water (120 degrees F or hotter). Immerse the assembly while it’s still hot, but make sure that the filler metal has solidified completely before quenching. The glasslike flux residues usually will crack and flake off. If they’re a little stubborn, brush them lightly with a wire brush while the assembly is still in the hot water.
You may have trouble removing flux if you haven’t used enough to begin with, or if you overheated the parts during brazing. Then the flux becomes totally saturated with oxides, usually turning green or black. In this case, the flux has to be removed by a mild acid solution.
After you’ve gotten rid of the flux, use a pickling solution to remove any oxides that remain on areas that were unprotected by flux during the brazing process. Generally, the best pickle to use will be recommended by the manufacturer of the brazing materials you’re using.