Within the past ten years electroplated iron and steel trimmings have been very extensively used, the plating being now so nicely done that it is impossible to distinguish the finished surfaces from bronze metal.
Nickel-plated iron hardware may also be obtained. This finish, however, is unsuited for nice work, as the nickel will tarnish by exposure to the atmosphere, after which no amount of rubbing will restore it to its original appearance.
As a rule plated hardware is not desirable, except such portions as are not subject to wear, as the plating will wear off in a short time, exposing the black iron beneath. Again, bronze plating and oxidizing is often used on very inferior grades of cast iron hardware, particularly door-knobs, butts, drawer pulls, etc., thereby giving to the uninitiated the idea that he is purchasing a good article, when in fact it may be a very inferior one.
In specifying plated hardware, therefore, the architect should confine himself to those articles that are not subject to wear, and of which the base is known to be of good quality. Plated hardware should not be used where it will be exposed to the weather.
Bower-Barff Finish. - The most appropriate finish for iron hardware is that obtained by the Bower-Barff process, which converts the surface into magnetic oxide of iron (by means of heat and superheated steam), in which condition it is absolutely rustless. The color of the iron when polished is a lustrous ebony black, especially appropriate for offices and public buildings and some portions of fine dwellings.
All ornamental wrought iron hardware should be finished in this way.
The regular Bower-Barff process is quite expensive, and is controlled under license by a few firms, The Yale and Towne Co. being the sole licensees for builders' hardware or trimmings.
There are other methods of getting a similar effect on iron goods, and most manufacturers have some such method, but these do not, as a rule, give the rich black color of the regular process, nor are they generally considered quite equal in quality.
A good deal of dead black hardware is finished over bronze ; while this looks well at first, it wears off after a time so that the bronze shows through.