Galvanising provides a particularly rust-resistant finish for metal products. Products with a galvanised finish are much less likely to show rust, except where the galvanised coat wears off in use. In areas where products will be exposed to salt water (eg sea-fronts) serious consideration should be given to using a galvanised based, as otherwise the products will need repainting as much as every year (depending upon the level of exposure).
Galvanising doesn't provide an especially attractive finish though galvanised products can be painted over to enhance appearance. Strictly speaking galvanised metal should weather for about 6 months before being painted. In practice, painting early means that paint may chip in use, though for most products this is not noticeable. It can be painted over with a primer and standard household gloss paint (eg to match house colours) if required.
Hot dip galvanising is a modern and technically advanced product that protects iron and steel from rust by providing a thick metallic zinc envelope that completely covers the steel surface and seals it from the corrosive action of its environment. A high quality zinc coating is welded to the steel surface by an alloying reaction between zinc to form a tough, durable and impervious coating. This protects the steel by electrochemical protection, also known as sacrificial protection because where there is damage or minor discontinuity in the sealing coat of zinc, the zinc sacrifices itself to protect the steel to which it is alloyed. It will go on doing so until almost the last atom of zinc and significantly reduces corrosion of steel and iron. Unlike organic paint coatings that require frequent renewal, the galvanised coating cannot come off as it is alloyed to the surface of the steel, coating every surface of the product which can be reached in the hot dip process, both inside and out. In hot dip galvanising a product, the galvaniser cleans the steel by degreasing and pickling to obtain a chemically clean surface. The galvanising reaction between zinc and steel takes place in liquid zinc, at a high temperature for a few minutes.
This abrasion resistant coating can ordinarily last for many years with little or no maintenance. Galvanising does have a finite life, however, and its effectiveness as a barrier depends directly on the thickness of the coating and the environment (for example it will have a shorter life when exposed to salt water or pollutants).