At the end of
the medieval period, the “lunar” method of manufacturing sheet glass began to
be widely used in Europe. It was also based on the blowing method. With this
method, at first the ball was blown, then it was flattened, the axis was
soldered to its bottom, and the workpiece was cut off near the blowing tube.
The result was a semblance of a vase with a soldered axle leg. The red-hot
“vase” rotated with great speed around the axis and, under the action of
centrifugal force, turned into a flat disk. The thickness of such a disk was
2–3 mm, and the diameter reached 1.5 m. Further, the disk was separated from
the axis and annealed. Such glass was smooth and transparent. Its
characteristic feature is the presence in the center of the disc of a bulge,
which experts call the "navel."
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| The “Lunar” Method of Manufacturing Sheet Glass |
The lunar mode
of production made sheet glass available to the population. However, another
more sophisticated method came in to replace the lunar mode already at the
beginning of the XVIII century. This new method has been used throughout the
world for almost two centuries. In essence, this was an improvement of the
medieval method of blowing, which resulted in a rather large cylinder. Its mass
reached 15 - 20 kg and from it, as a result, glass sheets with an area of up
to 2 - 2.5 m² were obtained.
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| The Method of Cylinder |
This
method allowed to obtain window glass of good quality and relatively
inexpensive for the general population. Thus, the problem of a bright and warm
dwelling was resolved only in the XVIII century. This was achieved by the work of
many generations of glassmakers for two millennia.
Margaret
Thursday, September 5, 2019
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