Natural/Sulphuric Anodising | Silchrome Plating Ltd

What Is Anodising?

Sulphuric Anodising (also referred to as Natural Anodising) is a process most popular for Aluminium Components in which the naturally occurring thin oxide layer on the surface of the part is extensively increased to form a thicker, protective barrier. The extended barrier which is created is porous in nature and so can be dyed for a decorative finish.

What is The Process?

Anodising is an electrolytic process in which components are immersed in a vat containing a dilute sulphuric acid solution. This promotes oxidation onto the surface of the component which extends the existing oxide barrier layer. Unlike in electro-plating where an amount of material is being added onto the surface, in Anodising the Oxide Layer will form both above and below the surface (with roughly half above and half below) this means that Anodising will not chip or flake off, although may require sealing.

The Oxide layer that is formed has a honeycomb structure that is very porous in nature and so can be dyed to provide a range of finishes. Silchrome’s most popular colours include Clear, Black and Red although other colours are available on request. The thickness of the film can range between 5-25 microns where 10-15 microns are usually required if coloured dye is to be added.

Although it is most popularly used on Aluminium components, the process can also be carried out on Titanium and Magnesium Alloys.

What are The Advantages?

Anodising provides components with increased hardness, wear and corrosion resistance. This corrosion resistance can be improved through sealing, although will still be attacked in more chemically corrosive environments. Natural Anodising will certainly resist scratching and abrasion and is an electrically resistant coating. For applications with a higher level of wear, you may wish to consider Hard Anodising instead.

The colour of Anodised components can be matched batch to batch, providing the same grade of alloy is used each time. Different alloys will give different shades of colour despite the same process taking place and some will be duller in appearance than others.