Zinc ammonium chloride is the inorganic compound with the formula (NH4)2ZnCl4.

[1][2][3] Steel to be galvanized passes through an acidic cleaning process to remove iron oxide "mill scale".

After this process, the surface of the steel is very active and oxide layers begin forming immediately upon exposure to the atmosphere.

This allows the molten zinc in the proceeding galvanizing step to maximally adhere to and alloy with the surface of the steel.

[4][5] Zinc ammonium chloride is a Class 9 hazardous material (Miscellaneous) according to the U.S.