Hot Dipped Galvanised Steel or Zinc Spraying

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Weethered and aged galvanised steel Harts tongue fern sculpture Chemically aged galvanised steel railings Freshly galvanised steel gate

Galvanising is a very effective and zero maintenance method of preventing steel from rusting when used outdoors. The work to be protected is immersed in a bath of molten zinc which reacts with the surface of the steel, coating it with a thick durable layer of zinc.

This coating is said to be "sacrificial" since the zinc will slowly corrode away, whilst electrochemically preventing the steel from corroding. In normal circumstances it can offer many decades of protection. All Verdigris' exterior steel work is galvanised as a matter of course.

Galvanised steel has an attractive metallic appearance which is often used as an exterior finish. When fresh it has a shiny silver appearance, though this will slowly turn dull grey over a few years. Because galvanising is an industrial process, its finish can be rather variable. Usually it is smooth and shiny but some areas may be slightly more rough or dull, with the occasional lump or drip from being immersed in molten metal. Very fine detail is often masked by the zinc coating.

Galvanised steel can be painted but special paints must be used; conventional paint does not adhere well to a galvanised finish. Prior to painting, the zinc coating is often artificially aged with an acid to provide a better key for the paint to stick to.

The acid turns the zinc a matt mottled grey black that is a very attractive finish in its own right. It quickly weathers to a powdery grey white finish to resemble old lead that is particularly effective at highlighting the character of forged steel. It is an engaging, practical and zero maintenance coating that improves its appearance with age.

Often galvanised steel is painted using powder coating. However, we do not recommend this since although it may look good initially, powder coating is notoriously bad at sticking to galvanised steel and will drop of in very large flakes over the course of a year or so and is difficult to touch up.

Since hot dipping floods and masks fine detail, an alternative is to spray molten zinc metal onto the steel. This method is equally as effective at preventing corrosion where the spray can reach but it will not reach inside hollow box section steel.