Zinc ammonium chloride is commonly known as Flux, and is used for galvanizing steel. It is 60% ammonium chloride and 40% zinc chloride in it. The pH of zinc ammonium chloride should be 4.2.
Zinc ammonium chloride is not to be confused with zinc ammonium carbonate.
Zinc ammonium chloride is not necessarily 60:40 ratio of Ammonium chloride and Zinc Chloride as stated by the writer above. The ratio is varied as per type of usage for the flux. However 60:40 is a more running grade of zinc ammonium chloride. Apart from ammonium chloride and zinc chloride, it also contains galvanizing additives like glycerol, sodium dichromate, borax, etc. For a good write up of zinc ammonium chloride one may visit Zinc Ammonium Chloride Flux