Most motorists who read this almost hackneyed phrase in manufacturers’ catalogues have little or no idea of the very intricate process of chromium plating. They think that it takes the place of ordinary nickel plating and is similar to it except that it does not tarnish ; whilst this is true of the cheapest possible methods, which are liable to rapid deterioration and, in many cases, are not rust-proof, the highest class chromium plating is additional to nickel plating. Furthermore, the nickel must be of special quality and finish if high-class chromium plating is desired.
The number of parts of a car or motorcycle which are chromium plated is much larger than most would imagine. A guess at the quantities which pass through a chromium shop in a week, say, would probably be incorrect by many thousands. An example may be found in the case of the Triumph Company where well over a quarter of a million pieces—varying in size from nuts to radiator shells and motorcycle tanks—are chromium plated each week.
The actual process is as follows : Fitments in their bare metal state are first polished and scoured so that all grease may be removed. They are next heavily nickel-plated and then super polished. The reason for this is that it is impossible to obtain a finer finish on the chromium than is obtained on the polished article prior to chromium plating ; as a matter of fact, any blemish becomes very much more obvious. It is necessary, therefore, for the amount of nickel to be greater, and for the finish to be better, than would be required if the surfaces were to be left in the nickel plated state.
During deposition of the chromium each part must be separate from the next and some distance from it. Every single piece, therefore, has to be wired or attached to a frame so that it gives good electrical contact. The labour involved in this work alone can well be imagined when 250,000 pieces are handled weekly !
The various components are then immersed in the chromium vats and are left there for a predetermined period according to their size and shape. They are next washed in hot water, before being placed in a hot soda solution ; they are then washed in hot water once more and are smothered in hot saw-dust for drying purposes. Finally they are examined and, although very bright when taken from the vats, the more important pieces are given a burnishing operation.
If the least imperfection is discovered, they are rejected and returned to the ” stripping ” shop where caustic soda and sulphuric acid baths, both subjected to electrical current, remove the chromium and nickel plating. The whole work then starts over again.
Numerous and complicated as the processes may sound they are essential for a first-class, lasting finish. The problems, however, are the manufacturer’s alone and, provided that the process has been properly applied the purchaser may enjoy the advantages of chromium plate without any doubts whatever.
This brief description of the system employed at the Triumph Works show that there is more behind the sentence “All Bright Parts Chromium Plated ” than would appear at first sight.