Chromic Anodising

Why choose sulphuric anodising?

  • Good corrosion resistance
  • < 5µm coating thickness
  • Good paint base

Specifications that we offer:

Similar treatments:

Why choose Metal Finishings Ltd?

  • Fast turnaround - as short as 24 hours
  • High quality
  • ISO 9001 and AS 9100 certified
  • Nadcap accredited
  • Nationwide service with our trusted courier
  • No-obligation quotations
  • Free certificates of conformity

What is Chromic Anodising?

Anodising is a very popular protective treatment for aluminium. Like all types of aluminium anodising, chromic acid anodising forms a corrosion resistant, amorphous layer of aluminium oxide. Anodising is performed by passing a current through parts (attached to the anode), in this case, in an electrolyte of chromic acid.

Chromic anodising was the original method of anodising and is sometimes referred to as the Bengough-Stuart process. Chromic acid anodising can produce films up to 5 µm. Chromic acid anodising produces films that are considerably more grey than sulphuric anodising.

Due to the use of hexavalent chromium, chromic acid anodising is gradually being phased out wherever possible. Laws and regulations are being enacted around the world both restricting its use and in some cases banning it outright. If you are designing a new product or updating an existing one, you may wish to consider using sulphuric acid anodising instead. Our technical staff will be able to assist you with any decisions about this, so please do contact us.

Specifications Offered

We can work to other specifications, but the above are our most popular. Please contact us with your requirements.

Information for Designers


Chromic acid anodising can be sealed or left in the unsealed condition. It is generally left unsealed for customers who plan to paint it.

RoHS and REACH Compliance

Chromic acid anodising may contain hexavalent chromium and we cannot guarantee how much it will contain, so we do not claim RoHS compliance. Chromic acid anodising is REACH compliant.