What is anodising?

The anodising process sounds complex, but it’s based on electrochemical principles. Here’s how it works:

1. Preparation: The metal, typically aluminium, is first cleaned thoroughly to remove any dirt, grease, or impurities. This ensures that the anodising process is even and effective.
2. Electrolytic bath: The cleaned metal is then submerged in an electrolytic solution, usually containing sulfuric acid. This solution acts as the electrolyte in the electrochemical cell.
3. Electrical current: An electrical current is passed through the solution, with the metal acting as the anode (hence the term “anodising”). This causes oxygen ions to be released from the electrolyte and bond with the metal atoms on the surface.
4. Oxide layer formation: The reaction between the metal and the oxygen ions forms a layer of metal oxide on the surface. This layer is porous, which allows for further treatments (such as dyeing).
5. Sealing: After the desired thickness of the oxide layer is achieved, the metal is sealed to close the pores. This step enhances the metal’s resistance to corrosion and wear.

The result is a surface that is harder, more durable and more resistant to environmental factors than the original metal. The thickness of the oxide layer can be controlled depending on the intended use of the metal, ranging from a few micrometres for decorative purposes to several tens of micrometres for industrial applications.

The short answer is no, stainless steel cannot be anodised in the same way as metals like aluminium.

The reason lies in the fundamental differences between the two metals. Aluminium naturally forms a thin oxide layer when exposed to air, which can be thickened and controlled through the anodising process. Stainless steel, on the other hand, already has a passive oxide layer that provides corrosion resistance. This layer is not porous like the one formed on aluminium, making it unsuitable for the anodising process.

However, stainless steel can undergo other surface treatments, such as passivation or electroplating, to enhance its properties. These processes can improve its corrosion resistance, appearance and durability, but they are not the same as anodising.

Anodised metals are incredibly versatile and are used in a wide range of applications across various industries. Here are some of the top uses for anodised metals:

• Aerospace: The aerospace industry relies heavily on anodised aluminium due to its lightweight and durable properties. Anodised components are used in aircraft structures, engines and interiors, where they provide excellent corrosion and wear resistance.
• Architecture: Anodised aluminium is a popular choice for architectural applications, such as window frames, curtain walls and roofing. Its durability and aesthetic appeal make it ideal for both structural and decorative purposes.
• Electronics: Smartphones, laptops and tablets all use anodised aluminium casings. This helps to protect the fragile electronic components inside the devices.
• Automotive: In the automotive industry, anodised aluminium is used for both exterior and interior components. It’s commonly found in trim, wheels and engine parts, where its resistance to corrosion and wear is ideal.
• Cookware: Anodised aluminium is also used in the manufacture of cookware. The anodised surface is non-reactive making it safe for cooking and easy to clean.
• Medical equipment: The medical industry uses anodised metals for certain instruments and equipment. The process provides a sterile, corrosion-resistant surface that is essential in a medical setting.
• Sports equipment: Anodised aluminium is used in the production of some sports equipment, such as bike frames, golf clubs and camping equipment. Its lightweight and durable properties make it ideal.