Sulphuric Anodising

Example of black dyed sulphuric anodising Black dyed sulphuric anodising
Example of dichromate sealed sulphuric anodising Dichromate sealed sulphuric anodising

Sulphuric acid anodising, like chromic acid anodising, is a very common protective treatment for aluminium. This is achieved by forming an oxide layer on the surface of the aluminium that then protects from corrosion. The thickness of this oxide layer can range between 8µm and 25µm (depending on customer requirements). It is possible to achieve greater thicknesses using hard anodising. It is important to note with anodising, that it does not deposit material on the surface, it converts some of the material instead. Each surface only grows by 50% of the coating thickness.

Dyed Anodising

Aluminium (and anodised aluminium) has microscopic pores on the surface. This allows anodised parts to be dyed (although, it is not necessary). We offer a range of different dyes:

Other dyes can be ordered in for large orders or supplied by the customer. Colour samples can be made available on request.

Sealing

Metal Finishings Ltd can seal using both methods specified in Def Stan 03-25 (and others): boiling water seal or dichromate seal. Cold nickel acetate sealing is also available. Sealing closes the pores of the oxide layer, providing even greater corrosion resistance. Almost all anodising that we perform is sealed as part of the process. If, for whatever reason, you do not want us to seal your parts, it must be specified on the order.

Specifications/Standards

Our sulphuric anodising process conforms to:

Frequently Asked Questions

Is it possible to anodise steel?
No. However, we do offer protective treatments for steel, such as zinc plating, which we offer in clear ("silver") and colour (iridescent).