Anodising

Anodising

 

Anodising is an electrochemical process that converts a metal surface into a decorative, anodic oxide finish. The anodic oxide structure is made up of a layer of aluminium oxide on the surface of the aluminium which slightly increases the thickness of the metal.

The aluminium oxide is not attached to the surface like paint or plating. It is fully integrated with the underlying aluminium substrate, which stops it chipping or peeling.  It has a porous structure that allows for secondary processes such as colouring and sealing.

Anodising is achieved by immersing the aluminium into an acid electrolyte bath and then passing an electric current through it. A cathode is mounted to the inside of the anodising tank; the aluminium acts as an anode, so that oxygen ions are released from the electrolyte to combine with the aluminium atoms at the surface of the part being anodized. Anodising is effectively a process of highly controlled oxidation.

It requires both a specialist skill and an exact grade of metal to achieve the desired result, so it's not an easy technique to perfect! Accordingly many manufacturers steer clear of the method and only offer plated finishes, albeit the number of finishes possible is more limited using this process.

At Phos, we have the benefit of many years of experience on our side, which allows us to harness the craft and apply it to our range.

Advantages & Disadvantages:

Advantages

Disadvantages

  • It's easy to maintain; it can be cleaned with water and mild detergents to restore the original lustre,
  • UV stable and will not peel or flake, as it is integral to the metal,
  • Protects the base metal to offer a deeper, richer metallic appearance,
  • Offers a wide range of high quality architectural finishes.
  • Can only use specific grades of aluminium for this process,
  • Cannot be used on Stainless Steel, which is durable to mortar, salt, chlorine and marine environments,
  • This method draws from the base metal so it can be subject to colour variations. In high grade metals a 95% match is possible between batches, in low grade metals no match is possible,
  • Consequently harder to replicate consistency between batches compared to plating, 
  • The most expensive solution for small quantities (requires a higher-grade alloy in addition to the already high set up costs).

Applications:

Anodising can only be applied to aluminium. This finish is ideal in external environments due to its durability because its UV stability will protect the light frame against weathering, subject to being installed away from acidic materials such as mortar or saline environments. Despite being durable, any small scratch can cause this to corrode quickly. Our Team will be able to advise further. Anodising is the most premium finish, compared to plating and powder coating and can achieve a variety of finishes which are authentic to the material they are mimicking.

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