Boric Acid and Brass Alloy Can someone explain why boric acid prevents zinc from vapourizing out of the brass alloy when it is being melted?  What is the actual chemistry occurring and why?
Thanks
It depends on the temperature, specifically the 1700 F +/- boiling point of zinc , not the flux. At 1700 F the zinc will vaporize regardless of any flux . I never saw a single component flux, likely the the flux also contains soda ash, silica, etc. and it does protect the molten metal from atmosphere by forming a physical layer. Footnote: many years age I worked with copper alloy fluxes and found that for some alloys, the boron promoted the formation of spinels in the metal ; These are exceptionally hard materials that essentially prevent machining of the bronze/ brass.