An ingenious invention, of which dire necessity was the mother, is that illustrated in the accompanying engraving. It was devised by F. D. Millet director of decoration at the World's Fair, and his assistant, C. Y. Turner, for painting the woodwork of the fair buildings. The enormous areas to be painted, and the necessity of doing the work expeditiously, made it a matter of the first importance to devise some plan whereby the usual method of painting by hand could be done away with. Besides the necessity of doing this work promptly, the character of the construction was such as to make it impracticable to get at considerable portions of the surface, and the rough lumber, just as it left the saw, was extremely severe on brushes.
After several ineffectual attempts to devise a serviceable painting machine, the gentlemen above named succeeded in solving the problem by the construction of the machine here shown, with which it was found possible to spray color upon the surfaces to be covered, very satisfactorily, ante at a rate many times greater than could be done by hand in the usual manner.
The machine operates on the principle of the "atomizer." The plant consisted of a five horse-power electric motor, which furnished the compressed air for the spraying nozzles. The engine, compressor and color reservoir were mounted on a truck furnished with wheels, so as to be readily movable from place to place as the work progressed. The color (kalsomine), previously mixed and ready for use, was poured into the reservoir, which was then closed tight, and the compressei air was admitted near the bottom at a pressure of about 20 pounds to the square inch. By this plan the color was kept thoroughly mixed and any deposit was prevented. From the top of the reservoir the air was then conducted through a pipe to a point on the outside near the base, and here, by means of a ½-inch regulating valve, the color was passed into the main air pipe, with which it was carried along, through any desired length of ordinary tinch garden hose, to the nozzles. These were formed of a brass pipe, flattened to 1/10 inch wide by 1½ inches long at the aperture, from which the commingled air and color issued as a fine spray. One of these machines was found to be sufficient to furnish enough coloring material for supplying two nozzles, each being operated by a skilled painter, who handled th apparatus after the fashion of a lawn sprinkler. A glance at the picture accompanying this article will give an excellent idea of the machine and the mode of operating it.
The backward condition of many of the buildings but a short time prior to the opening day made the problem of painting them an extremely perplexing one, and but for the invention of tin very ingenious and simple mechanical expedient here described, it would have been practically impossible to finish the work in time. With the aid, however, of fourteen of these machines, each operated by three men, the work was done in an incredibly short space of time.
A comparison of hand work with the machine, showed that two nozzlemen with the machine were able to do the work of twenty hand painters. The quality of the work done with the machines was entirely satisfactory. An additional advantage afforded by the machines was the ease with which the work could be carried on in the coldest weather, when hand painting was impossible. This was accomplished by forcing the compressed air through a coil heated by a coke fire, by which the temperature of the color could be regulated at will. The successful solution of the troublesome problem hene described forms an interesting episode in the history of the preparations for the great exhibition.
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