The apparatus employed for this work is of the simplest character. The car body is placed upon a platform mounted upon wheels. This is made of exactly the right size to fit between a V-shaped metal trough which surrounds three sides of the body and is intended to receive the superfluous paint, a considerable quantity of which drips into it from the body as the enamel is applied. This trough, a sketch of which is shown in Fig. 121, is slightly inclined so that the paint which drips off all runs to one point, where it passes through a gauze covered orifice, descends to a small tank beneath, whence it is pumped up to the elevated tank above and is then ready to be used again.
This elevated tank is cylindrical and holds, perhaps, 25 or 30 gallons. It is stationed overhead some 12 or 15 feet high. From this tank descends a flexible metal pipe or hose ending in a slotted nozzle, opened by a lever, which is operated by the thumb of the workman and is closed by a spring. This completes this simple though very effective apparatus.
The body of the car is made of stamped steel which has already received a protective coat of paint of a dull red colour, the body being placed upon the platform or bogie and being placed in position with the V-shaped trough surrounding it on three sides. The first or undercoat is given by rapidly passing the slotted end of the lever valve over the surface, upon which the paint literally pours out. The top part receives attention first and the paint runs down over the surface, which it covers completely, excepting perhaps here and there, where the discharge of paint is directed, and the whole of the outer surface of the car is, as already stated, completely covered in two minutes. This coat dries semi-flat.
In order that the discharge pipe may be kept nearly vertical and be moved around the car as the different sides are dealt with it is provided, at its upper end close to the point where it joins the tank, with a brass swivel union and a horizontal arm which swings around. A stop-cock is also provided.
The undercoat having been applied the body is allowed to rest for a few minutes until the dripping ceases. It is then wheeled on the bogie across the room to an oven, in which it remains for one hour at a temperature of 160° F. This heat is found to be sufficient to bake the paint but is not high enough to injure the woodwork which, of course, forms part of the body. At the expiration of the hour a little stopping of inequalities of the surface is usually found necessary, but in any case the surface is lightly rubbed down with fine glass paper.
Fig. 121.—Sketch of Trough Tank Used in Flowing on Paint.
The body is now brought underneath a second tank with the V-shaped surrounding trough exactly as before described, and here it receives another coat of enamel or paint, which in this case has a little more body and gloss. After stoving as before and at the same temperature the surface is carefully but rapidly rubbed down with powdered pumice stone and water applied by means of felt pads.
There are a series of four troughs and tanks in all, corresponding in number with the coats to be applied. From the third one the body receives a third coat, is then baked or stoved, rubbed down with powdered pumice and water, thoroughly cleaned off, and from the fourth tank receives the final coat of varnish which completes the operation. This coat of varnish is not stoved but is air-dried. The finish is a blue-black picked out with very dark blue, and it is free from any signs of runs or drips; in fact, no one could tell how the application was made. As already remarked, the coats of paint are somewhat fuller than would be the case if they were applied by spraying, and the durability is thereby increased.
The output from this department is 70 cars a day, a number which would be practically impossible if the work were not so splendidly systemised.