Abstract: A method of defining an identification marking on an article comprising the location, on a surface of the article in a required area, of a stencil defining a required identification marking; the stencil preferably being temporarily adhered to the surface by means of glue or adhesive, applying to the stencil to contact the surface through the identification marking defined by the stencil, an active substance which is corrosive to, or a solvent of, the material defining said surface of the article; allowing such contact between the active substance and surface to persist for a selected length of time; and thereafter removing the stencil and active substance adhered thereto from the article and cleaning the surface.