In many industries the application of paint for preservative or ornamental purposes is imperative and the item of expenditure is an important one.

There is abundant evidence to prove that the application of paint, either by means of dipping, spraying or other mechanical means, effects an enormous saving of time over the old method of using brushes, while the coats of paint are more durable and thorough.

This saving of time not only lowers the cost of production to a very considerable extent, but it permits of a large increase in the output.

The process of "flowing-on" enamels and varnishes described in the following pages effects an even greater saving of time in those cases where it is applicable. The extent of this saving can be judged by the fact that a complete coat of enamel can be given to the body of a four-seated touring car in the almost incredibly short time of two minutes!

These processes are used to a very large extent in many industries, particularly those connected with metal work and engineering. In the United States of America and in many parts of the Continent they have reached a high degree of perfection. In Great Britain the adoption of the methods is rapidly increasing.

It is hoped that this book will be found of service to manufacturers who desire to ascertain whether the processes can be economically employed in their particular industry or to those who contemplate putting in a plant for the purpose.

It should also be helpful to those who have not been very successful with a trial plant or who desire to bring an existing plant fully up-to-date in its equipment. And it should be said at once that the few cases of failure which have come to the notice of the author have been found on investigation to be due either to the use of paint unsuitable for the purpose or the adoption of a plant which is unfitted for the object aimed at. Three examples may be given. In one small castings were dipped in black paint, but it was found that "tears," or runs of paint which did not dry properly, often occurred. Here, clearly, the paint was at fault. It was too thick for the purpose and did not dry hard quickly enough. The remedy was obvious.

In another case iron casements were dipped horizontally in a shallow paint tank and the time involved in lowering them to obtain a complete immersion was considerable. In this case the shape and size of the tank were not suitable. It should have been deep and narrow, so that the casements could be dipped vertically. The idea that the paint would "settle out" if a deep tank were used was shown to be erroneous.

In a third case spraying had been tried for coating metal casements, when it was found that the saving effected in time was more than counter-balanced by the waste of paint. Of course, spraying was not suitable for a job of this kind, the surface to be covered being so very narrow. Such work is done most successfully by dipping.

The degree of perfection to which the process of dipping has been carried in America is indicated by the fact that it is largely employed for piano cases and many other articles requiring a perfect varnish finish. This process is fully described in these pages and has been successfully carried on for some years. This fact demonstrates very clearly the possibilities of painting and varnishing by immersion.

All the principal appliances used for spraying paint, lacquer, enamel, varnish and similar liquids have been described at length, but no attempt has been made to prove that any one appliance is superior to another. The details of each apparatus are given, and for the convenience of the reader, the manufacturer's name and address. It is suggested that those who contemplate the adoption of paint dipping, or spraying, should get into touch with all these firms, and carefully investigate their respective merits before coming to a decision.

The services of an expert will usually be found desirable, for, although in engineering works much of the necessary apparatus and accessories may be made on the premises, the exact details, such as the kind of paint and the exact design suitable for the particular purpose, are largely matters to be decided upon in the light of experience.

ARTHUR S. JENNINGS.

365, Birkbeck Bank Chambers,
High Holborn, W.C.

August, 1915.