Zinc Ammonium (Chloride ?),,that's used in the galvanizing process as a prep dip before the zinc coating is applied. Never heard of it used for bbl browning,,doesn't mean it can't work!
Zinc Chloride is a rapid rusting agent,,it's a common soft solder flux,,most commonly called 'acid flux'. It will rust and keep on rusting for you unless thoroughly washed from the surface.
Ammonium Chloride , used to commonly be called Sal-Ammoniac in block form for soft soldering, Water soluable and very good rusting agent for bbl browning. You can still buy it as SalAmmoniac. Works well as a flux when melting scrap gold or silver ect to remove the trace metals.
Never tried the first one,,but the next 2 work fine. Neither will go bad if mixed in a soln and left on the shelf. Might rust through a tin jar cap though! Plastic works best I've found.
