FINISHES FOR HARDWARE Finishes for hardware vary all the way from a coat of ordinary paint up to gold plating. The cheaper forms of butts, locks, hooks, etc., are japanned. This process gives a satisfactory wearing coat which looks well and is a good pro tection against rust. When plain hardware is to be used it is commonly buffed by the use of a rapidly revolving emery wheel. The finer the wheel the higher the grade of surface. Very bright surfaces are produced by the use of a cloth wheel saturated with rouge.
When iron or steel hardware is used, it should be protected in some manner from the effects of rust. Japans, lacquers, and even paints or var nishes, are used for this purpose. Plating with copper, brass, or bronze is effective, and even dipping in a copper solution or in molten tin is resorted to as a protective coating.
The process is one of the best finishes for indoor hardware, but is not suitable for exposed outdoor work. The process consists of a chemical change in the outer surface of the iron or steel, effected in a high temperature fur nace. The result is a permanent lustrous black color which needs no additional protective coat ing. While this finish is almost unexcelled for interior work, yet, when exposed to the action of dampness in unprotected locations, rust forms in the small pits which are liable to occur during the process, and spots develop which in time cause the skin of the finish to flake off around the spots, thus leaving the metal unprotected.
For cast or wrought brass or bronze, the nat ural surface polished or subjected to the action of a sand-blast forms an attractive finish. In places where wear and handling are not exces sive, a coat of colorless lacquer may be given to prevent tarnishing. Fancy finishes are given to brass and bronze by the application of chemical solutions which, instead of coloring the surfaces, really discolor them. These finishes do not wear well when handled.
For plated articles which are handled but lit tle, a thickness known as single plate is all that is necessary. For knobs, handles, etc., a thick ness known as triple plate should be used.
Silver-plating wears well, but should be used only on plain surfaces which can be cleaned easily. The action of sulphurous gases tarnishes silver, and articles coated with such a plating are subject to constant attention.