The colour of iridescent stainless steel derives from an extremely thin ceramic layer formed on the surface of the stainless substrate by physical vapour deposition. No pigments or dyes are involved at any stage of the process. The core steps are as follows:

• Vacuum environment: deposition takes place inside a chamber held at very high vacuum, ensuring a clean reaction environment.
• Metal evaporation: an electric arc or electron beam vaporises a solid metal, typically titanium, into atomic form.
• Deposition reaction: the metal vapour combines with a reactive gas such as nitrogen or oxygen to form a micron-scale ceramic layer on the substrate surface.

The underlying mechanism behind the colour shift is thin-film interference . When light strikes the nanometre-thick coating, waves are reflected both at the coating surface and at the interface with the metal substrate. During interference, certain wavelengths are cancelled while others are reinforced, producing an iridescent effect that changes with the viewing angle.

In engineering applications, the grade of the base material directly determines the corrosion resistance and structural strength of the finished product. The commonly specified substrates are compared below.

Grade selection is therefore driven by exposure conditions rather than appearance alone: specifications acceptable in dry interior settings may prove inadequate where salt spray or sustained moisture is present.

Although the PVD coating bonds with the metal at the molecular level and offers high resistance to delamination, routine maintenance must follow specific rules to protect the optical interference layer at the surface.

• Cleaning: restrict cleaning to a soft cloth, warm water and a mild neutral soap solution.
• Prohibited substances: acidic or alkaline chemicals, abrasive pads and strong scouring powders must not be used, as they can disrupt the smoothness of the nanometre coating.
• Protection during installation: sharp tools should be kept away from the surface during construction, and edges should be shielded from mechanical damage.

These constraints apply throughout the service life of the panel, since the colour layer is integral to the surface rather than applied over it. Damage to the coating is consequently a structural matter rather than a cosmetic one, and mechanical contact remains the principal risk in both handling and long-term use.