31. Polishing by Tumbling.—-Excellent results in polishing large quantities of small pieces, may be obtained by tumbling. The material to be polished should be thoroly dry. The parts are then placed in a tumbler as shown in Fig. 10. Cut up paraffine wax into small pieces, using about one-fourth pound to each tumbler full of toys. Allow these to tumble several hours. This will distribute the wax evenly over the parts and produce a polished surface.
The tumbler as shown in Fig. 10 is turned by hand, altho it could very easily be placed in a lathe, where one is available.
Fig. 10. Tumbler for polishing small pieces
32. Care of Brushes.—A suitable place should be provided for brushes that are not in use. A tin-lined keeper is recommended. Brushes should be suspended so that their bristles will not touch the bottom of the keeper, and have the liquid in which they are kept come well up over the bristles, so that none of the paint or varnish may dry in the butt of the brush.
33. Paint Application by Means of Compressed Air.—In recent years, great advancement has been made in the application of paint by means of compressed air. The early use of pneumatic painting equipment was confined almost exclusively to the application of finishing materials such as japans, enamels, lacquers, varnishes, etc., on manufactured products. But in the past few years improvements have been made which eliminate all of the difficulties originally experienced and make possible the use of this method for interior and exterior painting, such as buildings, ships, etc.; and at present, a large portion of factory maintenance work is done in this manner. Excessive fumes have been eliminated and all materials can be applied without removing the volatile thinners, solvents, binders, etc., thru air reduction. This is brought about thru the use of low pressure and the perfection of ingenious patent nozzles and other improvements.
34. Uses of Pneumatic Sprayers.—Pneumatic paint sprayers, or air brushes, are extensively used in the manufacture of toys, furniture, automobile bodies, sewing machines, telephones, electrical equipment; in fact, very nearly all manufactured products, as well as on ships, structural steel and iron work, bridges and buildings.
The speed of the air brush is very great compared with hand-brush work. Usually, an air-brush operator will accomplish as much in one hour as a hand or bristle-brush worker will in one day; and it is possible to obtain an even coating, free from sags, runs or brush-marks and better results are obtained than with the hand brush method. A film of paint can be applied in one operation equal to two hand-brush coats, as it is not necessary to reduce paints by thinning as much for air brush application, in a great many instances, as is the usual practice for hand-brushing. The air sprayer can also reach places inaccessible to the hand brush, and a perfect coat can be applied over rough, uneven surfaces, which could not be obtained by hand-brushing.