The invention is the chemical composition and method for forming a chemical conversion coating on ferrous metal surfaces and subsequent coloring of said conversion coating through the application of a water-soluble dye. The conversion coating has an ordered crystalline structure composed of ferrous oxalate or other ferrous dicarboxylates. The conversion coating can be colored through the application of a water-soluble reactive dye which bonds with Fe (II) within the ferrous dicarboxylate matrix, bound to the dicarboxylate molecules, thereby becoming water insoluble and permanent. When sealed with an appropriate rust preventive top coat, the result is an attractive and protective finish of minimal thickness which can be applied through simple immersion process techniques. Said finish can serve as a final protective finish on a fabricated ferrous metal article and also affords a degree of lubricity for assembly, break-in purposes, or anti-galling protection and serves as an adhesive base for paint.