METAL FINISHING
David E. Colglazier
The finishing of metal hardware is an often overlooked or misunderstood aspect. The finishing of metal is just as important as the finishing of wood; both are offered protection from the elements, desirable qualities are enhanced, and patina can be acquired artificially without the waiting time required by nature.
Generally speaking, all hardware is finished somewhat by workers at the factory where is it produced before it reaches the consumer. This step removes undesirable stems, burrs, and colors left by the manufacturing process. Most is also polished to a sheen determined to be acceptable to consumers. In the antique restoration field, whether furniture or housing, this factory finish is not normally sufficient or pleasing. Chemical baths are sometimes used by the manufacturer to provide an "antique" look and scratches are sometimes put on the surface to give it a burnished look. These processes do not go far enough to provide a realistic\par reproduction of aged hardware. Although we employ some of these same techniques in our metal finishing, we can also provide extra steps that add highlights and artificial patination.
As with wood, natural antique finishing is somewhat of an oxymoron -- it is not possible to provide a true antique finish in a mere matter of minutes or hours. But the effect can resemble an antique finish if one follows some steps that occur during the true day to day, year to year wear of an item. The trick here is to build the desired finish up in layers somewhat as is done in wood finishing.
The steps most commonly used are:
1) Strip any factory applied coatings off the metal. This step gets us down to the base metal when waxes, lacquers, pigments or paints have been applied. We use regular paint stripper or lacquer thinner depending upon the applied finish.
2) Scratch the base metal using steel wool, Scotch-Brite, steel or brass brushes. This step dulls the polished metal down to the desired luster so that light diffusion occurs replicating years of polishing with abrasives and wear.
3) Clean the hardware thoroughly. This is absolutely necessary to get a clean base metal so that any chemical baths change the base metal color evenly. While this might seen contradictory to getting a final uneven worn look, it is the step that guarantees a consistent base color to begin the patination process. I use TSP., lye, Dawn dish soap, ammonia but about any alkaline will do when soaked overnight. A slight discoloration generally results from this step but is corrected by further processing.
4) Chemical baths are used next to get the base metal color to an acceptable darkness. I prefer to dilute my solutions to slow down the action so I can watch it and stop it just where I want it. These solutions last a long time if not contaminated so it is important to not use metal tools and containers unless you want them darkened in the process. And always wear rubber gloves without holes in them. Fumes are not generated by the solutions we sell. Some chemicals cause a blackening of metals while others achieve a more brown color. We have both types available so you don't have to look all over and then wonder what color you will get. It has been suggested to me that gun bluing works but I have yet to try it.
5) After the base color, I lightly polish the areas where wear would occur most. A light abrasive such as a grey pad or metal polish seems to do the trick here for me. This leaves the recesses darker and brings out a contrast replicating patination and wear. You might decide to leave the hardware bare at this point and I often do, but you might consider one last step.
6) A lot of hardware is coated with a clear lacquer at this point. This protects the coloration that you have applied. I find this coating makes the patination too "fakey" so I just apply a floor or car paste wax. This provides some protection but allows for a continuation of the natural aging process so that our previous coloration only takes on a more realistic look with time.
There are probably many more steps that can be taken, but these are the ones I use most in our business. Remember, metal finishing is as much of an art as a science so do not be afraid to try new things.