Over time, if not protected anything made of metal will be susceptible to rust. This is why Alpha Rail supplies galvanised metalwork unless specified otherwise. But have you ever wondered why galvanised metalwork changes in appearance over time?
All of our materials are galvanised to BS EN ISO 1461 (2009), which is a process that involves dipping the metalwork in molten zinc, where a reaction occurs. The molten zinc can reach temperatures of up to 500°C. This reaction forms a coating on the metalwork’s surface that protects it from the elements that may cause corrosion. This is a widely used application and very cost effective as opposed to using stainless steel. In most environments, galvanised metalwork can last for periods of time in excess of 20 years.
When first taking delivery of a freshly galvanised metalwork product such as pedestrian guardrail, many customers will be delighted by its shiny, glistening appearance. As the months go by however, the metalwork will fade or dull into a matte grey colour. However, don’t be put off. By no means is the metalwork any less protected than it was before – it has actually become more durable.
Once the metalwork is coated and exposed to oxygen in the atmosphere, it causes a layer of zinc oxide to begin forming on top of the galvanised finish. When moisture in the air reacts with this along with carbon dioxide, the zinc oxide will form the protective layer over a few months known as ‘zinc patina’. This layer is self-healing, very tightly adheres to the metalwork and cannot be washed off by rain, protecting the galvanised finish underneath.
If you would like to add extra levels of protection to your materials, you can opt for a polyester powder coated painted finish in a RAL colour of your choice. Not only does the polyester powder coated finish act as another layer to the metalwork, it also gives you the opportunity to further customise your railings and have them in any colour you’d like – be it to match county colours, a school theme, surrounding buildings and so on.
Although the most popular colours are black or moss green, almost any colour can be achieved with polyester powder coating and it allows you to enjoy the benefits of low maintenance. It is also more cost effective than a wet paint application that requires frequent repainting and multiple coats to achieve an even finish.
If you would like to discuss your next metal railings project please get in touch or complete the enquiry form.Tags: Galvanised metalworkwhy does metal dull in colourZinc patina