What is pre-anodisation and when is it needed?

If your property is located near the coast line or a large estuary, we would highly recommend a pre-anodised paint finish for your aluminium window and door frames. But what is pre-anodisation and why do you need it?

What is a pre-anodisation?

Pre-anodisation is a pre-treatment applied to the aluminium frames prior to the powder coated paint finish. Pre-anodisation adds an additional layer of protection, making the aluminium stronger and more resistant against the elements.

When is pre-anodisation recommended?

In many circumstances the powder coated finish is extremely durable and weather resistant, this high-performance coating is enough to protect the frames and ensures your glazing stands up to the test of time. However in aggressive environments where there are high levels of chemicals in the air such as salt and moisture, the aesthetics, performance and therefore lifespan of your aluminium windows and doors can be affected. As a result pre-anodisation is recommended in order to protect the frames/finish.

When a property is located near one of the following it is classed as being within an aggressive/marine environment:

  • Coastal areas (within 1 km)
  • Estuaries of large rivers (within 1 km)
  • Industrial surroundings
  • Railway tracks
  • Airfields
  • and indoor swimming pools

What are the benefits of pre-anodising?

Pre-anodising the aluminium increases the corrosion resistance of the frames and therefore increases the longevity and durability of the aluminium. Whilst still allowing the frames to be powder coated to give you a very large choice of colour options and finishes.

Pre-anodisation also helps to protect the powder coated paint finish from beneath. Reducing the chance of bubbling and lifting within the aggressive environment, creating an extremely durable frame.

Production process

During the production process the aluminium profiles are anodised prior to being powder coated. The aluminium profiles are first degreased and cleaned before being dipped into a chemical bath. Here an artificial oxidation process takes place, allowing the pores of the aluminium to open. The profile is then placed in a bath of metal oxide. Followed by a special steam bath to close the pores.  To ensure the very best quality, this specialized procedure is performed according to the strict guidelines of the European Qualanod-standard. The profile is then rinsed and air dried before the powder coating is applied, then baked in an oven at 200 ℃.


Due to the demands of the location within an aggressive environment, warranty periods are often affected, unless an anodised finish has been specified. A pre-anodised finish from Reynaers offers a 10 year warranty, meaning you can rest assured that your glazing will hold up against the exposed environment.

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