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Glass finishing technology

Hardening of glasses

It is known how often glasses burst, at other times even without any visible reason, but in most cases because of a sharp change in temperature, when, for example, hot water is poured into a cool glass or vice versa. In view of this, we consider it useless to cite the following simple, also repeatedly tested method of hardening, by means of which glasses can be given the ability to withstand abrupt changes in temperature. To this end, glasses, wrapped individually in straw, are placed in a metal (fish) cauldron, in which water is poured at room temperature and also put on a stove so that the water gradually boils. Then, holding the glasses in boiling water for 5-6 hours, the boiler is removed from the flame and covered with some blanket, so that the water cools slowly. When the water temperature is equal to the room temperature, the glasses can be considered already quite hardened and they can withstand, without any break, sharp changes from hot water to cold water or back.

Pencils of this kind can be prepared from the following composition: 4 elements by weight of spermacet, 3 elements of fat and 2 elements of wax. Then, depending on what color pencils want to have, 6 parts of dry paint are added to this mixture. The mass thus produced remains to be molded in the form of sticks, and the pencils are ready. They can equally well be scribbled to act as notes, in no way spoiling the glass itself, porcelain or metal.

To make the window panes opaque, you should dissolve the yellow "special" wax in turpentine and add a little dessicating agent (drying) to this mixture so that it quickly fades. This mixture is smeared with window panes, evenly smoothing it with a tampon from a silk cloth with cotton wool. If you want to get a colored surface, you can add some dry paint in the powder to the mixture.

In some cases, it is useful to replace paper labels, glued on glass bottles and banks, to apply matte inscriptions directly on the glass. Such label labels are more convenient not only in that they are stronger than paper ones, but also it is not so easy to substitute them. Therefore, we consider it useful to bring the following composition, recommended for etching on the glass of matte label inscriptions. In 0.5 liters of water, dissolve 36 g of sodium fluoride, 7 g of potassium sulfate. Immediately prepare another solution: in 0.5 liters of water, 14 g of zinc chloride are added, and 65 g of hydrochloric acid are added. When used, both data of the solution are mixed in equal proportions by also using a soft pen or a fine brush to draw letters on the glass. After half an hour, a matte inscription-label is made on the glass with a brush or pen.

They wrap the tube in which they want to cut it, a sufficiently wide strip of paper so long that it wraps the tube several times, also glue the ends, and it should be ensured that the edge of the paper exactly coincides with the place of the proposed cut. Next to this piece of paper, another strip of paper is stuck in the same way, so that between them a very narrow space of bare glass of uniform width along the circumference is obtained, along which it also has to cut through. Strips, before wrapping, it is useful to moisten a little. Then place a narrow space between the pieces of paper over the fire (cylinder of a kerosene lamp or an alcohol burner). The tube is rotated over the flame, until the space of the unprotected glass between the papers does not get warm enough at all, so that a drop of cold water, lowered to this place, causes a neat, also smooth cut. Paper wrapping a glass tube, prevents the penetration of heat to the surfaces covered by them, also because the flame acts particularly intensively on an unprotected strip of glass. Beforehand, to direct the flame to the glass tube, it is necessary to dry the pieces of paper that are put on the tube well, because the dampness on the glass can lead to a rupture of it on the wrong line.

A thin steel drill, heated to white, hardened in mercury or a piece of sealing wax is also honed. Then prepare a saturated solution of camphor in turpentine, moisten them a drill, planted on the calyx, and also drill the glass, which is thus wetted at the drilling point with the said solution. In this way, it is possible to drill a glass with a thickness of 1 cm in less than one minute.

In order to drill a hole in the glass, we recommend to take a trihedral file, lower it into turpentine and carefully drill a hole.

You can also drill a glass on a lathe with a copper rod, lubricating it with oil and sprinkling with emery. Particular attention should be paid to the hole, at what time the drilling process is coming to an end, and only the final refined layer remains, as if the glass can easily crack.

For this purpose, prepare a steam solution - one of 100 g of water, 12 g of sodium fluoride, also 2 g of potassium fluoride, but the other - from 100 g of water, 20 g of hydrochloric acid and 5 g of zinc chloride. Equal parts of each solution are mixed before use, also applied with a rubber stamp on the glass, which must previously be well wiped.