General Mouth blowning is a technique that involves swelling of molten glass in a bubble or ball, using the blow pipe. This method took a prominent position on the introduction of the middle of the first century BC until the late 19th century and is still widely used today as a technical format. The process involves blowing air in short bursts a portion of molten glass gathered on one side of a tube. This has the effect of forming a rubber layer inside the drop of glass that matches the exterior caused by the removal of heat from the oven. The technician can then blow into the tube to inflate the molten glass into a bubble and worke into a desired shape. Skilled workers are able to provide almost any form with the rotation of the tube, swing and control the temperature of the track and blowing. They produce a wide variety of glass objects, Transforming raw material into glass takes place around 1315 ° C. Glass emits enough heat to occur almost blinding. The glass is then left to "fine-tuned out" (allowing the bubbles to rise from the mass), then the working temperature is reduced to the oven to about 1100 ° C. In this phase, the glass appears to be a bright orange color. Although most are between 870 and 1040 ° C, the "Soda-lime" glass remains somewhat plastic and workable at temperatures up to 730 ° C. The gradual cooling is usually between 370 and 480 ° C. The glass blowing takes place in three kilns. The first, which contains a crucible of molten glass, referred to simply as "kiln." The second is called "glory hole", and is used to reheat a piece in between steps of work. The final furnace is called "cooling wave" is used to cool the glass slowly, over a period of several hours to several days, depending on the size of the pieces. This prevents the glass from cracking due to thermal stress. Historically, all three were involved in an oven with a set of progressively cooler chamber for each of the three purposes. History - Origin  The blown glass is originally invented by the Phoenicians around 50 BC somewhere along the Syro-Palestinian coast. The earliest evidence comes from a collection of waste from a laboratory glass, including pieces of glass tubing, glass rod made of tiny bottles, cast in a mikvah, a ritual bath in the Jewish quarter of Old City of Jerusalem dating from 37 to 4 BC Some of the glass tubing is “fire-shut” recovered from a side and partially inflated by blowing through the open end to form a small bottle, thus considered as an elementary form of blowing, therefore, the tube that blows not only represents the initial efforts of experimentation by artisans in glass blowing, is also a revolutionary step that led to a change in the conception and a deep understanding of the glass. One such invention is quickly overshadowed all other traditional methods to shape the glass.                                                                                                                                                                                                 Source: en.wikipedia.org  Stefanidis Chris - Stefanidou Zoe  G.P.