PVD coatings and architectural ironmongery
By Ian Desmond
Looking at the history of materials used for taps and handles and the modern-day options.
Stainless steel is now used widely on a vast range of commonplace household items. Metal finishes, achieved with the PVD process, are now adding a new dimension to really make items such as bathroom fixtures and architectural ironmongery not only stand out but stand the test of time.
Taking a step back into history, metals used for taps and bathroom fittings have come and gone in terms of preference. Due to its corrosion resistance, nickel was the popular tap finish from the 1880s up to the 1930s when at this point chrome was introduced. Chrome has experienced a resurgence in recent years for people going back to this metal. Nickel is still around in fact with finishes that vary from a chrome-like polished finish or a more stainless steel-like matt finish.
Many manufacturers today are seeing the benefits of using PVD technology for their finishes on taps and other bathroom products such as waste systems and shower heads. It is the PVD process that has transformed fixtures making them extremely durable and easy to clean, also the coatings are resistant to fingerprints or water spots making grime less likely to appear.
The process of PVD coating involves the deposition of zirconium nitride, titanium nitride, or other metallic ion combinations which are formed under low vacuum conditions. The finishes which are formed with the PVD process are considered practically indestructible as various thicknesses and coating types are possible and the process can be used on almost any material from brass to plastic.
The process involves individual parts being hung up and put through a nine-step thorough cleaning process. Sound-wave vibrations and chemicals then work by preparing the surface for coating. After drying, the parts are taken to the PVD chamber where reactive gases such as nitrogen and acetylene are used with certain metals to form a thin, metal alloy that coats the parts. The finish is both highly durable and elegant.
Stainless steel door furniture such as lever handles can be designed and then given a colourful eye-catching PVD coating. The coating makes the surface extremely resistant. It is particularly abrasion and scratch-proof, which is why lever handles with PVD coating have a permanent shine even without constant rubbing. Colours such as bronze, brass and anthracite are often available.
PVD treated door furniture can be used in areas and situations where normal lacquered handles would start to look shabby either from an onslaught of weather or in areas where there are many people using them causing wear and tear. They have a extremely strong resistance to salt spray which makes them ideal for use by the sea where metal which is either untreated or perhaps lacquered or painted would certainly begin to tarnish fairly quickly.
Moving onto brass products;- traditionally polished brass architectural ironmongery would be finished with lacquer. However the PVD process can be applied here to make the metal more durable. Historically, regular dusting with a cloth or maybe a bit of elbow grease with furniture wax would be used therefore extending the life of the lacquer. Like varnish or paint, lacquer often breaks down in harsh conditions. Chrome or nickel can also be applied to a solid brass item to make it more long-lasting.
PVD brass is also used on door furniture which is slightly richer in colour to lacquered brass. As there is no lacquer on the surface of PVD, it has a brighter polished shine. However consistency is needed as the finish on lacquered brass may deteriorate with time, whereas the PVD brass would not. This means there could be a wider colour gap produced over time if different coatings were used. If, however, the coatings were used on different doors in one house it would be difficult to spot any discrepancy. You could of course use PVD brass all through the home and rest in the knowledge that you may not have to replace any door knobs or handles for more than 20 years.