Hot-dip galvanising involves immersing the steel in a bath of molten zinc at around 450 °C, producing a thick, metallurgically bonded zinc-iron alloy coating typically between 45 and 85 microns thick. This makes it suitable for structural and outdoor applications with long service life requirements. Electro-galvanising (also called electro-zinc plating) uses an electrochemical process to deposit a much thinner zinc layer (typically 5–25 microns) onto the steel surface. Electro-galvanised steel is generally used for lighter-duty indoor applications, fasteners or components that will be further coated. For structural profiles and outdoor use, hot-dip galvanising is the correct specification.
