Painting by Immersion and by Compressed Air: A Practical Handbook

by Arthur Seymour Jennings

CHAPTER II.

Painting by Immersion.

The process of painting various articles by dipping them bodily into specially prepared paint contained in a tank or other receptacle is a very old idea. It has, however, developed considerably in late years, and is now largely employed in many industries, particularly in the finishing of agricultural implements of various kinds, iron work and a hundred and one other articles. It is sometimes used in conjunction with paint spraying; that is to say, the first coat or coats may be put on by immersing the article to be painted in the paint, or varnish, and the final coat of enamel or varnish may be put on by means of a spray. In some cases, the final coat is applied by means of brushes in the ordinary manner.

Perhaps the simplest form of paint dipping is that applied to various articles, such as bolts, rings and small parts, which are placed in a wire basket and plunged into the paint. The basket is then hung up for a quarter of an hour or so to drain, and afterwards in another place, until such time as the paint becomes hard.

Another familiar example of painting by dipping is that of ordinary tapered cans, such as those which are used to contain varnish, etc. In this case, a piece of wood is introduced into the neck, the can is immersed in the paint up to almost the top of the neck, and is then placed upside down to drain and to dry. A paint which dries with a gloss is usually employed for this purpose, and it may be remarked that a good deal of this work is now done by spraying; in fact, a great deal of difference of opinion exists as to the respective merits of the two processes for this particular purpose.

Fig 1.—Cross Section Through Paint Tank.

Going a step farther, we come to the consideration of articles such as iron sashes and casements, parts of staircases, etc., which may be dipped into a tank containing, say, five to ten gallons or so. Such tanks are usually made to slant at the bottom in order to facilitate cleaning when necessary. Adjacent to them is provided a platform, usually lined with sheet iron upon which the paint can drip after the articles are removed from the tank, and a system of overhead rails for moving the articles from one part of the works to another. No agitating apparatus for the paint is required, but after the tank has been used for some time, say, for example, at the week-end, it is necessary to stir it up by means of a pole before the work commences. As a matter of fact, the articles being plunged in the tank, and their withdrawal, in itself stirs the paint sufficiently for the purpose.

In dealing with the larger-sized articles which are to be painted, such as reaping machines, the construction of the tank which may hold several tons of paint is naturally of a more elaborate character. Such a plant will consist, first, of the tank itself; next, the system of overhead railing; third, the apparatus upon which the articles to be painted are hung; and fourth, the hoists for lowering and raising such articles into and from the tank. It will be convenient to consider these parts which go to form a complete installation under their several heads, taking a more elaborate plant by way of example, it being understood that the plant may be simpler in form when the size of the articles to be painted is small, or under other circumstances, such as will be presently suggested.

The Tank.