To spray the same body takes only 6 to 8 minutes, and when it is noted that a fraction of the rubbing down is necessary in the case of the sprayed result, as against the brushed body, it will be granted that an enormous gain is to be effected.
Where two or more colours are employed, it is difficult to make comparisons as readily, but, generally speaking, it is the practice to employ two instruments per operator where the colours are applied one immediately after the other, as is the case with many electrical parts, and in this case a gain of 4 or 6 to 1 is shown over brushed work.
In some cases it has been found an advantage to spray one coat and to brush the other, especially where some difficulty is experienced in masking, and, in such cases, the only way to arrive at the most satisfactory method is by actual test.
In other cases, such as bronzing, with a celluloid medium, it is absolutely impracticable to apply these bronzes, save with the spray, unless the old method of varnishing and afterwards dusting on the bronze is adopted; but, of course, against spraying, such an obsolete method as the latter has absolutely no chance when speed is considered.
Iron piano frame manufacturers have almost universally adopted the system of spraying bronze on the frames. Where the old-fashioned method is still in use, it is usually because the quantity of frames to be dealt with is hardly large enough to justify the outlay required in the purchase of a plant.
Another advantage should be mentioned. The special celluloid japans now largely used for application by means of compressed air obviate the necessity of a considerable amount of rubbing down and papering, etc., which cannot be dispensed with when the liquid is applied by means of a brush.
For the purpose of comparison, it may be said that these japans may be sprayed upon such articles as buttons, medallions, electrical and bedstead fittings, and also on wood brush-handles and furniture, large and small, with a gain of 5 to 1 over brushing.
OBJECTIONS SOMETIMES URGED AGAINST SPRAYING.
Having explained the advantages of the spraying system, we may now consider the objections which are occasionally raised against it.
One of the arguments most frequently used is that the effect thereby obtained must be less durable than is the case of the brushed effect.