A bit more complicated Eldon
Courtesy of Steve Culver, President-Kansas Custom Knifemaker's Association
www.culverart.com
The smith will select materials for the elements in the damascus and then also the finishing chemicals that will create the desired appearance in the finished product. The color of the material after etching is determined by the alloys in it. Steel with a manganese content will typically etch black. Iron will etch gray through charcoal. Nickel will produce silver and chromium a light gray. The smith can use several different types of steel for his damascus and create layers in the pattern with varied shades from silver through black in the oxides formed by the etchant.
But, there’s more. If the damascus is deeply etched, it creates topography (high and low areas) on the surface of the material. Whatever element that is least affected by the etchant will be proud of the element that was more eaten away by the etchant. When lightly sanded, this higher element will become lighter in color, or silver. Typically, it is the higher carbon content material (steel) that etches quicker. This would leave the iron layers standing above the steel layers. So after sanding, the iron would finish silver. If the damascus is then blackened or browned after etching and sanding, the colors could again change, depending on which element has the greatest affinity for the coloring chemicals. So, it would be a stretch to categorically state the either the iron or steel will always be a certain color. It is all dependant on the finishing process.