Excellence in Chromic Acid Anodising

Advanced Solutions for Diverse Industries

Discover the unique benefits of chromic acid anodising at Hard Anodising Surface Treatments Ltd. Our process, known for producing soft, thin coatings, offers optimal electrical insulation and mild corrosion protection, essential for various industrial applications.

Compared with sulphuric acid anodising, the chromic acid anodising process gives relatively soft, thin coatings, normally of two to five microns thickness. These are used mainly for electrical insulation and general protection against corrosion under mild conditions. Unsealed coatings are used as a ‘key’ for paints and adhesives. It is light grey in colour, with a very silky texture.

Chromic Acid Anodising in Aerospace and Defence

In the critical fields of aerospace and defence, our chromic acid anodising process ensures safety and precision. The method’s thorough electrolyte removal is crucial for components involved with explosives and propellants, enhancing safety and operational integrity.

Applications Include:

  • Defence industry components – especially those involving explosives, propellants or pyrotechnics where complete removal of the electrolyte is essential for safety reasons.
  • Components containing crevices or small blind holes.
  • Pre-treatment for painting, especially in aerospace applications.
  • Flaw detection – a technique for identifying cracks, folds, inter-crystalline corrosion, machining damage, incipient melting of grain boundaries and cold shuts.

Chromic acid anodising is particularly useful when:

It is necessary to minimise the loss of fatigue strength of workpiece, as compared with sulphuric acid-type processes.

The item to be anodised contains crevices or small blind holes from which it may be difficult to remove electrolyte; traces of the highly coloured chromic acid are easily seen but, in any case, are non-corrosive towards aluminium. In fact, this ability is exploited in the field of crack detection where the presence of chromic acid leaching out of a crack is easy to detect.

The coating is on metal less than 250 microns thick, the process and resultant coating have a less adverse effect upon the properties of the underlying metal.

Specialised Treatments for Complex Structures

Our expertise is particularly beneficial for components with intricate designs. Chromic acid anodising effectively penetrates complex structures, including crevices and blind holes, maintaining the aluminium’s structural integrity.

Flaw Detection and Quality Assurance

Chromic acid anodising serves as an effective tool for flaw detection in quality control processes, identifying potential issues like cracks and corrosion, ensuring the highest safety standards.

Custom Anodising Solutions

We offer tailored chromic acid anodising services to meet your specific requirements.

Whether it’s aerospace components, defence equipment, OR advanced flaw detection, we’re equipped to provide precise and effective solutions.


What makes chromic acid anodising ideal for aerospace applications?
Chromic acid anodising is particularly suited for aerospace due to its ability to create a thin, protective coating that maintains the structural integrity and fatigue strength of components, which is crucial in high-performance aerospace applications.
How does chromic acid anodising aid in flaw detection?
The process of chromic acid anodising helps in flaw detection by revealing issues such as cracks, corrosion, and other surface imperfections. This is vital for ensuring the safety and reliability of components in critical applications.
Can chromic acid anodising be customised for specific component designs?
Yes, our chromic acid anodising services can be customised to suit specific component designs, especially for intricate parts with unique geometries, ensuring effective coverage and protection.

We are a dedicated provider of specialist metal finishing services, concentrating primarily on the anodising of aluminium.