Brazing flux is required to prevent oxides from forming while the metal is heated. 

The flux also serves the purpose of cleaning any contamination left on the brazing surfaces. 

The flux flows into the joint when applied to the heated joint and is displaced by the molten filler metal entering the joint. 

Excess flux should be removed when the cycle is completed because flux left in the joint can lead to corrosion, impede ...joint inspection, and prevent further surface finishing operations.

Compatible for welding brass, bronze and copper and also suitable for brazing malleable iron and steel.