Painting by Immersion and by Compressed Air: A Practical Handbook

by Arthur Seymour Jennings

The principal use of spraying in this work is to put on the speckled edges of books after they are sewed and before binding. This is usually done by splashing colour from a stiff-haired brush over a comb, but the method is a crude one at best. In using a spray for the purpose one of the simpler forms will do all that is required. The pressure must be lowered and paint removed some distance from the books until the requisite size of the spots or dots of colour is obtained. With a little practice this can be regulated to a nicety.

Carriages.

The remarks which will be found elsewhere, under the head of "Tramcars," apply to some extent to carriages also, and although the superfine finish required for a high-class carriage could hardly be produced excepting by the old-fashioned means, yet the processes of flowing-on and spraying could, without doubt, often be employed for the cheap and moderately cheap style of vehicles of various kinds which are now produced on so extensive a scale.

Cycle Parts.

Many parts of cycles are now painted by means of spraying, although some firms prefer dipping. Whichever process is used it is necessary, as a rule, to give at least two or sometimes three or even more coats, and to get a fine finish to rub down between these coats with powdered pumice and water, and, for the last coat underneath the finish, rottenstone and oil. The parts must always be stoved, as air drying enamels are not, as a rule, sufficiently hard to permit of their resisting the hard wear to which cycles are subjected. It need hardly be said that the method of handling various parts will to a great extent determine the economy effected.

The wearing parts of cycles are sometimes finished in the following manner, which is the method used by the Birmingham Small Arms Co. Although somewhat expensive it is certainly worthy of all praise, because it gives so durable a finish. The iron or steel parts are first thoroughly washed in American turpentine and are then stoved, the result being a perfectly clean surface. A coat of Calcutta linseed oil is then given by means of brushes and the parts are then stoved at 250° F., after which they receive a coat of what is called "Black Rubber Solution," an elastic enamel which dries with a semi-gloss. Then two separate coats of khaki colour japan are given and each are stoved at 280° to 300° F. A little rubbing down between the coats is sometimes necessary, and this is done with glass paper. The parts thus finished are very suitable for work which is to be subjected to very hard wear. At this writing the cycles are all intended for Government, hence the care taken in the finish.

Electrical Work.

Painting by compressed air is done in the case of many parts of electrical apparatus, the process being similar to that previously described. Thus the metal work of fuse boxes may be finished in this way with black japan, and one coat stoved at 250° F. or thereabouts will usually be found to suffice.

Among the large number of electric works where the process is employed may be mentioned those of W. T. Henley's Telegraph Works, Ltd., at Gravesend. The Airostyle is used in this case, and the work is done approximately from twice to three times as rapidly as it was formerly done with the brush.