Why Does Anodized Aluminum Always Have That Characteristic Metallic Sheen?
ohapuqa > 10-11-2019, 06:27 AM
After coloring, anodized aluminum has a characteristic “metallic” look. This is caused by two factors. One, because of the uniform electro-chemical etching, a rough surface is left behind. The deeper the pores, the rougher the surface will be but the colors will also be that much more durable.
Secondly, light striking the surface partly interacts with the colorant and partly with the uncolored metal at the top.
An illustration of different wavelengths of light being reflected from an anodized surface
Light changes colors as it reflects from an anodized surface.
So the light that bounces back to strike your eye will in fact be a combination of two distinct wavelengths interacting as they reflect from slightly different surfaces. This causes the distinctive shine of aluminum anodizing.