Sulphuric Anodising

We offer Sulphuric Anodising using Chromium Trioxide in accordance with Def Stan 03-25. For colour dying a 15% sulphuric acid solution is used.

Overview: Ideal for decorative applications including architectural metalwork, consumer goods, bike parts as well as general applications that require a clear natural finish. It is suitable for general protective purposes and for the production of a suitable surface for subsequent painting or adhesive bonding.

Key Strengths: There are a number of key features that make Sulphuric Anodising key for particular applications:

• Wide range of bright colours
• Electrically insulating finish
• Ideal for castings containing 5-7% copper or specified maximum total of 7% of (copper + nickel + iron)
• Specified process for components that come into contact with concentrated hydrogen peroxide (HTP)
• Compatible with explosives, propellants and pyrotechnics

Limitations: There are a number of limitations associated with Sulphuric Anodising:

• Unsuitable for items having riveted, lap or folded joints, tubes or other items where there is a risk of electrolyte becoming entrapped
• Not suitable for items less than 0.25mm thick
• Not suitable for alloys containing more than 7% copper
• Greater risk of fatigue strength loss
• Heat treatments must be carried out prior to anodising

Applications: General applications.

Tanks: We offer tank sizes up to 13' x 5' x 4'.

Thickness: Standard coating thickness is 5-7µm.

Finish: A range of colour dyes are available.

Jigging: Correct jigging is essential to the resulting finish, and good jig points are required, a consideration that should be made at the design stage of a component. The use of loose, sliding or intermittent contacts will result in an unsatisfactory connection and give rise to faults such as thin coatings, burning at the contact points or even failure to obtain an anodised coating.