Knowledge HubOxide layer and colour

What is anodizing?

An electrolytically grown oxide layer on the aluminium surface provides corrosion and wear resistance.

Request a quote Message us on WhatsApp +90 505 600 00 01

Key Anodizing Takeaways

01Oxide grows from the metal surface
02Thickness chosen by application class
03Pre-treatment quality is decisive

Electrochemical Anodic Oxidation and Film Thickness Classes

In anodizing the profile is connected as the anode and direct current is applied in an acidic bath. The oxide layer grows from the metal itself instead of being added like paint, so it cannot peel off.

Layer thickness depends on the application class; on exterior facades, thicker layers improve resistance to weathering. Colour is applied by dyeing or electrolytic colouring and sealed afterwards.

Pre-treatment quality (degreasing, etching, rinsing) determines appearance and durability; standards such as DIN 17611 define these steps.

EN ISO 7599 Anodizing Film Thickness Classes & Service Environments
Thickness Class	Micron Range (µm)	Recommended Service Environment
AA 10 (Standard Interior)	10 – 12 µm	Interior trim, furniture handles, shower enclosures, heat sinks
AA 15 (Moderate Exterior)	15 – 18 µm	General outdoor windows, doors, shading louvers and railings
AA 20 (Severe Exterior)	20 – 24 µm	Urban/industrial facades and solar PV module frames
AA 25 (Marine / Aggressive)	≥ 25 µm	Coastal architecture and high-salinity outdoor environments

FAQ

Can an anodized layer peel or flake off like paint?

No. Anodizing converts the aluminium substrate itself into an integral crystalline Al₂O₃ oxide layer rather than depositing an external film, so it cannot peel or delaminate.

Which micron thickness class should be specified for interior vs. exterior use?

Per EN ISO 7599, 10–12 µm (AA10) suits interior architecture and furniture, 15–20 µm (AA15–AA20) is standard for outdoor facades/solar, and 20–25 µm (AA25) serves coastal environments.