The starting material for all glass-blowing works are special glass piece, produced by Glass, - tubes of different diameters with different wall thicknesses. Such tubes are called drotom. To the workpiece includes a glass rod with a diameter of 10 to 20 mm wide cylinders or cylinders with a diameter of 150-200 mm with different bottom contours and different length capillaries with different wall thicknesses and different internal diameters (from 0.1 to 2 mm), barometric tube inner diameter from 2 to 4 mm, the tube crane and wall thickness 4-5 mm and a diameter of 30 mm, ball blanks in the form of flasks of different capacities with the rough openings, etc.
Glass blanks carefully culled control department of the enterprise. However, you must know the flaws (bubbles, stones, grit, foam, waviness) of glass pieces, which might go undetected. In addition, some defects may appear in the glass when soldering glasses together when soldering metals in the glass, etc.
Bubbles in the glass can be technological marriage, or may be formed as a result of outgassing during soldering of metal in the glass, at a burnup of dirt falling into place junctions, etc.
Bladder - a cavity filled with gas. Bubbles can be any shape and size, the smallest known "midge." In a place where there is a bubble, blank wall or junction is always thinner. When processing a flame burners harvesting in this area may be deformed or even break. When a leakage test products in a wall that has a bubble, there is always a danger of "breakdown" of the walls spark leak detector. Therefore, the workpiece with the inclusion of bubbles, it is better not to use paper at all. If this is the single bubble, then remove it and then carefully proplavit on the burners is the place. Articles in which the manufacture or assembly formed bubbles should be discarded.
Stones - it's all kinds of solid inclusions, which fall into the glass when it is cooking.These can be pieces of a charge of refractory materials furnaces, the inclusion of a large silica sand, etc. from the stone must be released immediately by cutting this section blank, as the workpiece to heat the flame and pull the stone is not always possible due to the large internal stresses occurring in the glass in place include a stone.
Groats - is the inclusion of small grains of quartz sand. Groats obtained in violation of the conditions for glass melting, excess sand in the batch. Glass with crumbs can not be applied to glass-blowing works.
The foam is formed during cooking of glass and is the inclusion of a large number of tiny bubbles. The foam can sometimes be seen on the surface in the thickness of the glass pieces. Glass with the foam should not be used.
Waviness is formed during cooking of glass and appear to ripple and layering pieces.Waviness visible to the eye.