PRODUCTION OF LENGTH RULE PROVIDED WITH BLACK SCALE ON GOLDEN COLOR SURFACE

摘要

PURPOSE:To produce a length rule having a black scale on a golden color surface in the production of said rule by coating black paint on a blank material of metal which is formed with a photosensitive film corresponding to the scale and is hardened at high temp. and stripping the photosensitive film then applying golden color plating. CONSTITUTION:Photosensitive liquid that forms a protective film against etching and a protective film for stopping a black color is coated over the entire surface of a blank material for products of straight rules and carpenter's squares made of metal. A negative having prescribed scale lines is applied thereon, and the coating is exposed and developed. The material lost of the photosensitive protective film only in the scale line parts is heated to 250-300 deg.C in a gaseous furnace, whereby the film is hardened, this is then subjected to an etching treatment to etch off the exposed scale line parts. Black painting that forms a protective film against plating having electrical insulation characteristics is filled in the scale line parts, after which the photosensitive protective film on the other surface is stripped. Next, golden color plating is applied thereon, whereby the length rule having the black scale on the golden color surface without plating in the scale line parts is produced.