Faucet Basics: Part 5
Stainless steel faucets don't need finishing. The material itself is the finish. But, most faucets are made of brass, a copper alloy. Refined copper is what is known in the industry as a reactive metal. Left to its own devices, it makes strenuous efforts to return to its pre-refined stable state as copper oxide. We view copper oxide as tarnished copper or verdigris (a word adopted from the French which means "green-gray", the actual color of copper oxide).
To make copper less reactive, it is usually alloyed with a less reactive metal, such as tin to make bronze, or zinc to form brass. Brass tarnishes less violently than copper, turning that golden brown color that we usually think of as "antique brass".
Native brass requires a lot of care. To reduce maintenance and increase durability, brass is given a protective coating. The most common coating is a layer of a non-reactive metal that does not require maintenance. But lacquer, paint, and powder coatings are also used. They are less robust than the metals, but the come in colors that metals cannot match. At least, not so far.
The most common finish used on faucets is another metal and the most common metal is chrome. Chrome does tarnish, but the tarnish forms a very thin coat on the metal which is nearly invisible and which prevents further tarnishing.
The original faucet finish widely used in the late 19th and early 20th centuries was not chrome, however, it was nickel. Native nickel tarnishes very slowly at room temperature, and when alloyed with zinc and copper, tarnishes barely at all. Its disadvantage, however, is that it is a soft metal and shows wear rather quickly. When, in the 1930s, chrome became widely available, it quickly became the preferred faucet finish.
Nickel is, however, making a comeback. With improvements in metallurgy and new methods of applying nickel to brass, including PVD (see below), the metal has seen a resurgence as a faucet finish. Highly polished and brushed finishes are the most popular. Brushed finishes have the advantage of not showing water spots or minor scratches as readily as polished finishes.
Bronze is also a perennial favorite faucet finish. However, some finishes called bronze are paints, not the actual metal. Bronze can take on a variety of shades that vary from light brown to nearly black. Basic bronze is usually a light brown color. Oil rubbed bronze (which is, of course, neither oiled nor rubbed), is darker, and often a non-metallic coating.
As a general rule, if the manufacturer calls the bronze a "living finish", it is probably not a metallic coating. If it has a lifetime warranty, it probably metal, but not necessarily actual bronze. It may be a more durable metal made to look like bronze. So, if you order your oil-rubbed-bronze bath fixtures and accessories from different suppliers, make sure the bronze finishes are a reasonable color match and that all are either living finishes or not.
Copper can be applied to brass as a finish, but most copper faucets are actually made of copper. Copper is a component of brass, and although softer than brass, it still works well as a faucet material. The advantage of a solid copper faucet is that the faucets are virtually lead-free. The disadvantage of copper is that, like brass, it tarnishes over time if not coated with a durable coating of some kind. The traditional coating was a lacquer. Today a simulated copper finish applied using PVD (see below) is replacing actual copper as a faucet finish. The simulated copper finish, made from zirconium or titanium, still looks like copper, but does not tarnish, and is very scratch resistant.
Pick any other low reactive metal and someone probably has made a faucet finish out of it. Gold and silver, while not common, are available by special order from most high-end manufacturers. Zinc is popular as a heritage finish, as is pewter (another copper alloy, this time with bismuth, antimony and either lead or silver). Both can be electroplated on brass.
Painted Finishes and Powder Coatings
In addition to the classic metal finishes, faucets can be finished in most colors of the rainbow. Nearly every major manufacturer offers black, but after that the colors available vary widely. Non-metallic colors are typically applied using some form or paint or powder coating. But, some are a glass-based glaze similar to the finish on bathtubs and toilets. Paint does not bond to the underlying metal like the metallic finishes, which bond at the molecular level. Most non-metallic coatings are tough, but brittle, and can chip if not handled carefully.
Certain faucet makers, those that also make sinks, use painted coatings to finish their faucets to exactly match their sinks.
for example, finishes some faucets to exactly match is engineered granite sinks.
Most faucet finishes are engineered to look out-of-the-box new for as long as possible. Living finishes (sometimes called organic finishes or architectural finishes), are an exception. They are designed to show wear and age over time. Used primarily in reproduction heritage baths and kitchens, they look well used out of the box, and age further with use, enhancing the rustic, antique look of the faucet. These are, by nature, relatively delicate finishes requiring routine maintenance. California Faucets, for example, recommends that its living finishes be allowed to age for one or two weeks, then waxed to help prevent water spots.
Ceramic and Glass Faucets
Some faucets are essentially pottery. They are made of vitreous china just like sinks, and can be glazed to exactly match your sink. At least one manufacturer,faucets. offers enamel faucets in the same enamel colors as its sinks and toilets. Metal can also be coated with glass enamel. The technology dates from the 1900s and used widely to protect iron and steel bathtubs and sinks.
Faucet Finish Technologies
How a faucet finish is applied makes a big difference to the durability of the finish. Three methods are commonly in use: electroplating, physical vapor deposition (PVD), and powder coating.
Powder coating is a process of applying pigmented finishes to a faucet. The term "dry paint" is not exactly correct, but close enough. The dry pigments are usually sprayed onto the faucet, then baked at about 400°F to set the coating. This causes the powder particles to melt, flow and bind to the metal of the faucet. The result is a tough finish, more durable than most liquid paints, originally developed for marine applications that resists corrosion for many years. Be a little careful of colored finishes, however. Some plastic-look faucets are actually plastic, and plastic faucets do not last.
Electroplating is the old standard. This involves immersing the faucet and the metal to be used as plating in an acid bath, then applying an electrical charge to both objects so metallic ions are drawn from the plating metal to the faucet. If the faucet is left in the solution longer, the plating is thicker. For thin plating, the immersion lasts just a few minutes. Thick plating takes longer, up to several hours.
One of the limitations of electroplating is that it is not usually possible from inspection alone to determine whether a faucet is thin or thick plated. When Chinese-made faucets were first placed on the market, their electroplated finishes were justifiably panned for being thin and fragile. It has been many years since this was a problem, but it illustrates that it is not possible to visually examine a faucet to determine the quality of the plating. The best way t avoid plated finish problems is to look to a known company with a solid reputation for your faucet, and be aware that a faucet with a short finish warranty, 5 years or less, is more likely to end up with plating problems. If the seller had complete confidence in its finishes, it would offer a lifetime finish warranty.
The electroplating process is scalable. While large companies have usually automated their plating operations, smaller manufacturers can electroplate equally well using a hands-on process little different from that used in 1900. Boutique faucet makers rarely invest in very expensive PVD technology (see below), offering instead some exquisite hand plated and polished finishes.
Even on a small scale, however, the process is inherently dangerous, involving very corrosive acid solutions, and resulting in waste by-products that can be very hazardous to the environment if not properly disposed of. faucets. a small manufacturer in Brooklyn, was recently caught dumping hazardous electroplating waste into the New York sewer system and was fined mega dollars.
Plating often involves several coats. Some metals cannot be plated directly to brass, so an intermediate metal (usually nickel or zinc/nickel alloy) undercoat may be necessary. Undercoats are also used in high-quality faucets to even out any small imperfections in the brass before it is given its final finish. A highly polished final finish may require two or more undercoats. Undercoats can also be used to reduce cost. Chrome is imported, and expensive, nickel is domestic, and not expensive, so a nickel undercoat means that less chrome needs to be used to achieve the same quality of finish.
Physical Vapor Deposition (PVD
PVD, also called "thin film physical vapor deposition", is the latest space-age faucet finishing technology, rapidly replacing electroplating as the finish of choice. It's still very new. Thirty years ago PVD did not exist outside of experiments in laboratories. Today, the technology is everywhere, and the machines required are getting smaller, faster and cheaper all the time. In a few more years your local auto repair shop may have one in the back room to freshen up the chrome on the bumper of your F-150. But, alas, not yet. The process is loud and scary and still involves as much art as science to get just the exact color and finish needed, which is why PVD operators make the big bucks.
The process is almost science fiction. Load a small chamber with unfinished faucets, then remove all the air and add back a carefully calculated mix of nitrogen and reactive gases. Add a chunk of the metal to be used for the coating, usually in the form of a rod. Heat that rod to a temperature so high that the rod dissolves into individual atoms. The atoms mix with the various reactive gases to get the color and finish effects you want and are then deposited in a very thin layer — 2 to 5 microns (.00008-.0002”) — on the faucets.
How thin is .05 microns? Well, a human hair is about 70 microns in diameter, so you figure it out. Obviously, it's pretty thin, barely the diameter of a single atom. But, because the coating bonds to the faucet at a molecular level, the finish is incredibly tough and durable. In abrasion tests, PVD finishes were found to be 10 to 20 times more scratch resistant than the old standard: chrome electroplated finish.
The coating material must be a metal nitride, but, the object being coated can be almost any material. It's possible to deposit metal on plastic, which is what makes inexpensive plastic faucets look more expensive. Undercoating is usually required for highly polished finishes because, unlike electroplating, PVD has no gap filling properties at all. Any scratch or mar on the faucet body will show through the finish, so the faucet body must be very smooth before the coating is deposited. It is not uncommon to see two or even three electroplated undercoats beneath a PVD final coat.
Only certain metals can be used as coating material because any metal used must be tough, durable, low-reactive and capable of forming a nice cloud of ions. Three metals are commonly used for decorative coatings: titanium, zirconium, and chromium. These are used to simulate many other metals that are not suitable for PVD, or which, being reactive, do not make good finish materials.
Different colors can be produced by varying mixture of reactive gases used during the deposition process, including brass and gold tones, nickel, chrome, and bronze tones, in a polished, satin or matte finish.
Brass PVD finishes, for example, are not brass, but zirconium or titanium, used to simulate yellow metals such as brass, copper, and gold. Gold is another metal that can be used, but it's very expensive. The only company that we know that uses actual gold in its PVD gold finish is
Chromium is used to imitate silvery metals. Combinations of metals and various mixes of nitrogen and reactive gases are used to achieve interesting finish effects such as the various bronzes, antique brasses, and nickels. Some manufacturers have managed to create metal finishes that do not exist in native metals, such as black. Chrome, however, is still chromium, although PVD chrome is much harder than electroplated chrome, and to be preferred.
The limitation of PVD is the cost. The initial investment for the equipment is coming down, but still very high, and the process is relatively slow compared to electroplating. It takes longer and costs more. So, expect to pay more for a PVD finish over electroplating. For your money, however, you get a no-kidding lifetime finish.
To watch a California Faucets PVD machine in action, click here, and prepare for loud noises.
Much of the difference in price between a quality production faucet such as is polishing. Most faucet finishes are not quite perfect when they emerge from the finishing process. They then have to be polished. In most mid-range faucets, the polishing is by machine. For high-end faucets to achieve their trade-mark lustrous finishes, meticulous and very skilled, time-consuming hand polishing is required. The time is worth it, however. The luster and depth of high-end finishes are unmatched, and a sure sign that the faucet is a high-end product.