From the first discovery of the beauty and workability of cast synthetic resins and probably to this day, the greatest tonnage is consumed in the manufacture of costume jewelry, of both the low priced and "exclusive" types. The reason for this fact is not difficult to discover—in no other material can as much brilliance, color and attention-attracting ability be produced so quickly or so inexpensively. Its physical qualities and workability fit the requirements of the manufacturer perfectly, while its gem-like quality, fascinating colors and the multiplicity of designs and effects appeal to women as no other type of adornment has in recent years. Figures indicate that seven out of ten women buying costume jewelry this year will buy plastics— not that it is a woman's product particularly, because at the same time three out of every ten automobiles, two out of ten cigarette-lighters and thousands of other articles appealing to men will have more or less plastics incorporated in the design. Cast resin, "The Gem of Modern Industry" has almost completely replaced the imported semi-precious gem materials, ivory, crystal and other materials whose cost was so great as to severely limit the buying public. The fact that it is composed of liquids permits it to be colored with any of the available dyes, whereas other plastic materials were strictly limited in the colors that could be used. Its liquidity before hardening also permits the incorporation of mottled effects impossible with a material pressed into a solid from a powder. The fact that it is thermosetting, and hardens at atmospheric pressures and reasonably low heats and contains no active chemicals permits the use of coloring matters that would be damaged by other processes, enables the molder to incorporate rare woods and other materials unharmed in trie mold, casting the resin around it. Lastly, it is a domestic product and its complete manufacturing process requires only about ten days, providing for quick delivery in any color or shape required. These reasons briefly summarize the factors behind the sensational increase in the use of cast resins in the past seven years by manufacturers.
In making costume jewelry on a quantity basis, most of the products are made from special shapes, where possible, and from the standard rod, sheet and tube sizes which involve the least waste in the manufacture. Most of the work is done on automatic or semi-automatic machinery, some with special machines and many different types of special attachments and jigs. In the main, the equipment used is standard woodworking or metal-working equipment, the only changes required being the adoption of the special types of tool-points, abrasives, etc., required for fast work on plastics. Some shops even use this equipment interchangeably on wood, metal and plastics novelties. The great volume of work of course is on merchandise for sale in the chain stores at lower prices, but the only difference between a piece made to sell at ten cents and at three or four dollars is in the amount of work put into it and the type of fittings or materials combined with it. Practically the same equipment is used and the same methods followed, the only difference being that some shops specialize on a large quantity of low-profit-margin work, while others specialize in smaller quantities of higher-profit-margin work. A comparison of the low-priced merchandise and the quality grades is shown in Plates 2R and 3H.
The first operation in the making of practically any article is cutting-off. This applies whether the article is being sliced from a rod of material, or consists of an individual casting, the "flash end" of which must be trimmed off. This is usually done with an abrasive cut-off wheel, the operation being illustrated in Plate 2M. Articles like buckle-shapes for instance are usually "sliced" from a long special shape having the cross-section of the buckle, the buckles being sliced off in the proper thickness like so many slices of bread. Sometimes this slicing is done with the abrasive cut-off wheel; other shops use a "slicer". One of these is shown in operation in Plate 2N, slicing special shapes. The shapes—three of them at once,—are set in a jig which just fits them, shown at the left of the machine, after they have been immersed in hot water or other liquid for the proper length of time. Approaching the shape will be seen a reciprocating knife, driven by the heavy fly-wheel pulley at the right. As each slice is taken off, the shapes drop down against a stop the proper distance ready for the next cut. The cut-off pieces drop into the pan of cold water below the knife, and lie perfectly flat. They are then ready for the next step, which may be carving, attaching findings, or the tumbling-barrel. This machine will slice a shape almost as fast as an operator can feed it, the normal speed being about 250 strokes per minute.
If the blank so cut off requires facing, this is done in a specially-designed lathe illustrated in Plate 2P. In this case a special shape consisting of a circle with an anchor in the middle has already been sliced as above described. The lathe has a treadle-operated chuck, and the operator is shown inserting one of the pieces in this semi-automatic chuck, which operates without stopping the spindle. After inserting the blank with his left hand, the operator advances the facing-tool by means of the lever shown with his right hand, the shape of the cut depending on the shape to which the tool is ground and how it is mounted. Twenty or more pieces per minute can be handled in this way.
A slightly different type of lathe is used in making articles such as buttons and ear-ring blanks from rod stock. It is a hollow-spindle lathe with a treadle-operated or lever-operated quick-acting chuch, sometimes called a "rod machine". One of these is shown in operation in Figure 2Q. The rod is inserted from the left end of the spindle. Moved up against a stop (the back "tool" on the cross-slide) and chucked with a single movement of the operator's left hand, the machine work is all done with two movements of the right hand. By moving the sliding cross-slide toward the back, the operator machines the back of one blank, the face of the next one, and cuts off. all with the one tool and movement. There are many variations of course, using turret tool-posts and turrets on the tailstock for more complicated operations, following usual hand screw-machine practise.
Bracelets are cut from cylinders of the proper diameter and thickness, in various ways, some on the band-saw, some on the lathe and some on a milling machine with special attachments. In these, sometimes the work rotates as well as the tool, so that a few seconds operation with a gang-mill set-up will completely shape and cut-off a whole cylinder into bracelets. The band-saw is only used on bracelets where the bracelet is to be wider on one side than the other, in which case the table can be tilted to the proper angle and a jig used.
Such brooch and pin shapes as are not cut from special shapes having the proper contour are band-sawed or jig-sawed from sheet stock, several sheets being fastened together and sawed at once. If there are no inside cuts, the bandsaw is used, otherwise the jig-saw, although occasionally a design will permit of a punch being used, the piece is thin enough and the design simple, the material being first heated and softened. Blanks requiring a curved back are either bent after heating, or shaped from cylinder-section having the proper curvature. Patterns for outline sawing are usually made from thin sheet metal and the outline scribed on the top sheet, although various methods are employed, such as printing or mimeographing the design on a sheet of paper, pasting this to the sheet stock with rubber-cement, and sawing thru it. Blanking is also done with hollow mills.
Fifty percent or more of the shapes cut out as outlined above require a greater or less amount of hand carving. This, as explained in a previous chapter, makes use of a high-speed carving-spindle with special cutters, a battery of which is shown in operation Plate 2W. The carving looks quite intricate in the finished product, but in production of large quantities in a shop of this character, the work is done very rapidly, by expert operators who develope extraordinary speed and accuracy at this work. The high polish that the material takes catches and reflects the light to such an extent that even a simple carving has several times the effect of intricacy as the same amount of carving would have on duller and less colorful material.
All carving is done with the work held in the hand and guided solely by the operator's eye—no carving-designs are ever sketched on quantity work. No matter how difficult the carving, the operator quickly learns the movements by heart, and can switch from one design to another in a few moments. On especially large work, or work in which two or three different types of cutters are employed on the one article, the work is passed along the bench from one operator to the next, each one doing that part of the carving for which his machine is set up. In large shops such as the one pictured, each machine is equipped with an exhaust to carry away the chips; these can be seen at the back of the benches. Speed of course varies with the size and intricacy of the carving, but the objects pictured in Plate 2R, which is the type of work being run through this particular shop the day these pictures were taken, is handled at the rate from 100 to 300 an hour.
This practically completes the description of all machining operations done before the polishing stage is reached. Embossing is occasionally done before polishing, but usually afterwards. The "cutting down", ashing, buffing and polishing operations have been described in anther chapter. Some objects are ashed in a barrel, such as shown in Plate 2T, others on hand wheels, as in Plate 2V frequently using a simple jig to hold them. Plate 2S, shows a battery of these in operation, working with wet pumice powder and water. The wheels are hooded as will be seen, and the finished work is tossed into a bucket of water so that the pummy will soak off before the articles go to the next step in the step in the finishing process.
The attachment of findings, pins, hooks, etc., is usually done after the polishing operation, for two reasons. In the first place, the various compounds used in polishing would fill up the drill-holes and any crevices in the findings, and in the second place the findings would be damaged in the polishing process.
If any of these metal ornamentations are of cast bronze or other materials requiring treatment in their own right, this is done separately and the ornament is only attached in the completed state.
A description of the findings and ornaments used and their methods of attachment will be found in another chapter. The only difference in methods between those used here and those used by the home craftsman are that multiple-spindle machines are frequently used to drill several holes at once in their proper positions, and that press-fit findings are usually driven home with toggle-operated foot-presses, one of which is shown in Plate 2V. The only steps remaining are inspection and mounting on cards or packing in boxes.