Clear Glass

CHARGING THE RAW MATERIALS
The raw materials - principally sand, soda, limestone and dolomite-are kept in different silos. After being weighed separately they are mixed and then poured into the charging" hopper along with the cullet (crushed scrap glass). All these operations are fully automated.

MELTING IN THE FURNACE
The raw materials are melted in the furnace at a temperature of 1,550 J C produced by powerful fuel-oil and/or gas burners- As it melts, the mixture vitrifies and flows slowly down inside the furnace, undergoing a process known as "fining". During this process, the molten glass is kept at a high temperature (or several hours, enabling bubbles of air (rapped within it to escape.

FLOATING
As it comes out of the furnace, the molten glass is poured onto a bath of molten tin, where a sheet of glass is formed by flotation, From one end ofthe bath to the other, the temperature ofthe glass and ofthe tin gradually drops from 1100 C to 6ocr C Top rollers on either side, draw out the glass mechanically to give it the required thickness and width.

ANNEALING
The glass emerges from the tin bath in the form of a continuous strip. This is led by a roller conveyor to an annealing tunnel, known as a "lehr". Here, the glass is gradually cooled in a controlled way, in order to ensure perfect flatness and eliminate any internal mechanical stresses which could cause breakage. The glass comes out of the tehr at an ambient temperature, ready for cutting.

CUTTING
This cooled and hardened glass is then cut on an online cutting machine and despatched.