Trinkets Sales Inc.

How Glass Beads are Made

 The basic raw materials for the production of glass are glass-making sand, dolomitic limestone, potash and glass cullet. In order to achieve various colour shades, coloring agents are added to the batch, for example cobalt for blue color, and chromium for the green. These materials are melted in pot furnaces at temperatures of about 1300-1400°C. From the melted glass mass, bars of length of 120 cm and of the diameter 3 cm are drawn on a special equipment. These bars constitute basic material for the production of glass beads and other jewelery and chandelier components (e.g. trimmings, pressed animals, figurines, fruit...)

Pressing is a process in which glass bars are melted down at a temperature of about 800-900°C, and from the melted glass, semi-finished products are pressed. Two technologies are employed: either pressing on Kopal pressing machines or pressing on Matura pressing machines. In case of Kopal pressing machines, the end of the bar is melted down (about 5-7 cm), and the presser presses a semi-finished bead from this end, using a special pressing machine. With the Matura presses, the bars are melted down in a "pot" heated by a gas burner. From the bottom of this pot, a trickle of glass mass runs out, and an automatic pressing equipment presses semi-finished beads out of it.

During pressing, a seam is formed along the circumference of the pressed bead. The majority of these seams is removed in the raw-edging barrel, which is a many-sided (5-8 sides) wooden barrel where the beads are brought, and by the rotation of the same, the seams are removed. Next, the beads and loosened seams are separated on a vibration screen. The seams are employed as raw material for the manufacture of glass bars.

Now, the rests of the seams that have not been removed up to now, must be removed from the beads, employing the tumbling barrel for the purpose. The beads are brought into this barrel together with glass sand and water, and during the rotation of the drum, they get abraded.

The resulting beads are either a finished product already, or they may serve for further treatment. The finished product is called pressed beads. In this case, the surface of the bead has a sateen matt finish or it is lustered. The beads are lustered in polishing barrels; the process of polishing is 2-3x longer than the preparation of the raw material.

The beads intended for further processing are called semi-finished product for cutting. The surface of these beads is matted in the majority, with larger diameters half-glossy.

Cutting means cutting of facets along the circumference of the bead. It is effected on special machines. The beads threaded on needles are clamped in a special device - an apparatus pressing them down upon the circumference of the grinding tool, cutting the individual facets. The grinding tool is a cylinder of natural sandstone or of synthetic materials, of a diameter of 800mm and width of 540mm.

Once the beads have been cut, it is necessary to polish them. The polishing is effected in continuous electric furnaces or in chamber kilns. In continuous electric furnaces, the beads are polished on plates installed on a continuous belt at the temperatures of about 700-750° C. The passage of the plate takes 10-17 minutes, depending upon the type of the bead. In chamber kilns, the plates with beads are inserted into a frame which then is transferred into the kiln. The polishing is one-shot operation, i.e. the inner space of the kiln with the beads gets heated to temperature of 590-650°C, and after reaching it, the kiln is switched off and aired out. During the heat polishing in electric furnaces, the superficial layer of the bead gets melted, and in this way, its surface becomes lustred. After polishing, the beads are washed and dried.

The next step in the production is the control of quality, where the beads with defects occurred during their production are discarded. The inspection is carried out manually. The result of these processes are cut and polished beads, the so-called fire-polished beads.

The beads can still be subject to various types of surface treatment - e.g. vacuum metal coating, waxing, staining, luster glazing.

The finished and inspected beads are either sold loose or they serve as components for the manufacture of artificial jewelery and rosaries. A special treat of this production and sale is the fact that beads are not counted by pieces, but by bundles.