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The Greenwich Blade was clad with anodised aluminium sheet

The anodising process explained

Despite being a corrosion resistant metal, depending on the environment and application, aluminium may still corrode, tarnish, and oxidise. The process of anodising aluminium enhances its natural resistance to corrosion and helps offer a more aesthetic and consistent finish to protect its overall appearance.

Anodising is the process of using the aluminium as an anode within an electrolyte bath. When a cathode is positioned within the anodising tank and a current passed through the medium, the oxygen reacts with the surface of the aluminium creating an anodic layer. The longer the aluminium is in these conditions, the thicker the protective layer.

Because the anodic layer is actually formed by chemical reaction, it does not chip or peel.

The process of anodising increases the resistance of aluminium to wear and corrosion as well as offering aesthetic advantages and anodised aluminium is still 100% pure and recyclable. This process also used to add a natural colour to the aluminium.

How Does Anodising Happen?

Creating an anodic layer in its essence is a case of controlling and enhancing the natural process of oxidisation. It is a simple process but needs great knowledge, experience and precise equipment for a successful result.

  • The aluminium part is submerged in an electrolytic solution bath with the cathode attached to the inside of the bath.
  • An electrical current is then passed through the bath.
  • Oxygen will then start to form on the surface of the anode. This will let the metal oxide film grow on the surface of the aluminium that is being treated.
  • The quality of the layer may depend on the concentration of the solution and temperature.
  • After anodising, the metal is very porous and the skin easily attracts dirt and other substances. It is at this point a dye can be added and because the metal is porous, the colour of the metal skin can be changed.
  • The final stage is known as sealing. The surface of the aluminium is very porous and so a process is required to close the pores. Often, this involves dipping in a de-ionised water batch at high temperatures.
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