CHAPTER XVI.
Metal Spraying.
Although the spraying of metal does not really come within the scope of this book, the process is so closely allied to paint spraying that it is considered advisable to devote a chapter to the subject, particularly as the perfected process is of very recent date, and bids fair to be used successfully in many industries. It should be stated at once that a metallic coating may be applied to practically any surface, and that almost any metal or alloy may be employed.
Stated briefly, the process consists in melting metal in the form of a rod or wire, by means of oxygen and coal gas, or other gas, depending upon the metal used. The molten metal is sprayed at a high pressure, and a surface may be quickly covered with the metal of any desired thickness. A remarkable fact concerning the process is that the metal is cooled to an extent that renders it possible to hold the hand in the jet so as to receive a coat of metal without inconvenience, and samples of wood and fabrics may be coated with metal without injury.
A moment of consideration will render it clear that there is an immense field for this process; for example, as aluminium can be sprayed, a lining of that metal might be given to brewers' and cooking utensils, etc., while tanks, barrels, reservoirs, intended to contain acids and oils, can also be treated. In the production of blocks for printing, in decorative work and mural decoration, there is an immense field, while ships' bottoms, instead of being painted with composition, can be copper-plated or sprayed with any other suitable metal, in order to prevent incrustation. No doubt some very beautiful effects can be produced by means of the process.
It will be convenient now to describe the machine used for the application of the metals. It consists of a pistol rather bulkier, but not unlike in form, the usual spraying apparatus, see Fig. 142.
Fig. 142.—The Metal Spraying Machine or "Pistol."
