Hot-dip galvanising dips the finished steel in molten zinc. The zinc bonds to the steel and protects it even where it is scratched. It is the default for external steel such as balconies, stairs, gates and railings.
Powder coating is a coloured polyester or epoxy layer that is baked on. It gives a clean colour finish but on its own it can be undercut by rust if damaged.
Duplex: galvanised and powder coated
For external steel that needs a colour, the best result is both: galvanise first, then powder coat. You get the life of zinc and the look of a coloured finish.
Quick rule
- External, no colour needed: galvanise.
- External, colour needed: galvanise and powder coat.
- Internal and hidden: shop primer.
- Internal and visible: primer and site paint, or powder coat.
