Apple Inc.
Process for producing white anodic oxide finish

Abstract:

The embodiments described herein relate to treatments for anodic layers. The methods described can be used to impart a white appearance for an anodized substrate. The anodized substrate can include a metal substrate and a porous anodic layer derived from the metal substrate. The porous anodic layer can include pores defined by pore walls and fissures formed within the pore walls. The fissures can act as a light scattering medium to diffusely reflect visible light. In some embodiments, the method can include forming fissures within the pore walls of the porous anodic layer. In some embodiments, exposing the porous anodic layer to an etching solution can form fissures. The method further includes removing a top portion of the porous anodic layer while retaining a portion of the porous anodic layer.