Hot-dip galvanizing is a common name for galvanizing technology that forms a zinc layer on the surface of steel material by immersing steel or steel products in a tank containing high temperature molten zinc. Since the galvanizing layer is applied after forming, processing or assembly, it is possible to apply a complete seal of galvanizing zinc layer.
References：Wikipedia: Hot-Dip Galvanization
However, due to the characteristics of the production process, hot-dip galvanizing takes several tens of seconds to several minutes to finish, so the alloy layer tends to "grow" and develop as shown in the photo below. The iron contained in the alloy layer is oxidized, which increases the risk of cracks and peeling of the galvanizing layer.
Hot-dip is a fairly simple galvanizing process in which the manufacturer or galvanizer hoists the steel product on a crane or similar, and then submerges it in several pre-treatment baths, flux bath, molten zinc bath, quenching bath and finally an optional secondary coating bath.
Video of the hot-dip galvanizing process