Optical Methods of Studying Surface Finish

SYNOPSIS

Five optical methods are discussed here by which the surface finish of polished or electrodeposited metal surfaces may be studied. Four are dealt with briefly because they have been adequately described in the literature. The fifth is believed to be new in its application to metal finishing. Preliminary results obtained for polished brass surfaces and for various electrodeposited metal coatings are discussed.

The presence of an oxide film has a marked influence on the optical behaviour of a metal surface. The properties of such a film may be learnt from the methods here outlined. Of particular practical interest is the anodic oxide film, familiar long since as a surface finish for aluminium and of current interest as a possible protection for other metals. The methods described are of general application. Illustrations are provided of the results obtained on anodised tantalum surfaces.