The iron to undergo galvanization ought to be free of impurities. The iron is placed in hot alkali such as caustic soda and is heated to 194 degrees Fahrenheit. The alkali gets rid of all organic contaminants such as grease and oils.
The pickling stage involves the removal of rust from the surface of the iron. First, the iron is rubbed with sandpaper, and then the iron is dipped in distilled water to eliminate any alkali present. Finally, the iron is dipped in hydrochloric acid at room temperature to eliminate any remaining rust.
In the dry galvanizing stage, the iron is dipped in an aqueous solution of zinc ammonium chloride. The purpose of this step is to precoat the iron with a thin layer of flux. This flux removes any oxides that form on the iron at the pickling stage and prevents formation of more oxides.
The galvanizing stage involves immersing the iron in a bath of pure molten zinc at a temperature of about 840 degrees Fahrenheit. The excess zinc coating is eliminated by either wiping or draining. Finally, the galvanized iron is dipped in a solution of sodium dichromate to provide a protection for the zinc coat.
The galvanized iron is air cooled to prevent the galvanized iron from reacting with atmospheric moisture, which would lead to white rust formation.