Altering a metal body surface

Abstract

A method for changing a metal body, especially an aluminum alloy body, and, in particular, a method for producing a uniform metal body surface for use in achieving desired light reflectance characteristics and/or other useful attributes. The method comprises (a) preparing a metal body in a first solution by producing a first coating on at least a desired portion thereof with the first coating providing a substantially continuous outer surface on the metal body and (b) treating the metal body to achieve substantial uniformity throughout the desired portion of the metal body. In the treating step, substantially all of the first coating is removed in a second solution. The metal body has a substantially uniform roughened surface after the treating step which is sufficient to substantially optimize diffusive reflectance and reduce spectral reflectance of the metal body surface. The preparing step is preferably accomplished by anodizing. The treating step is preferably accomplished by electroetching, etching, and anodizing in that sequence. The final shade of gray of the second coating after the last anodizing step is determined by the contacting time in the etch step and the voltage or current in the last anodizing step. The invention has many attendant advantages including metal body surfaces that have substantially uniform roughness with the surface texture being reproducible.