| abstract |
A broad range of colors within the visible spectrum can be obtained by light interference and multiple refraction in an anodized aluminum product, by electrolytically depositing on an aluminum-based substrate an aluminum oxide anodic film separated from the substrate by an aluminum/aluminum oxide interface. The aluminum oxide anodic film comprises at least three superimposed aluminum oxide anodic layers having different porosities and separated by interfaces between each other, the innermost one of said anodic layers having a non porous barrier layer arranged between the bottom of the pores thereof and the aluminum/aluminum oxide interface. Pigmentary inorganic material is deposited within the pores of the superimposed anodic layers and at least in portions of the interfaces between them, the different colors being produced by varying the current and/or time conditions when depositing the innermost one of the aluminum oxide anodic layers. |