How to make Glass
There are hundreds of recipes for making glass.
0ne of these is the following:
- 59 parts of quartz sand,
- 17 parts of soda,
- 15 parts of dolomite,
- 4.5 parts of limestone,
- 3 parts of sodium sulphate and carbon, and
- 1.5 parts of felspar.
These ingredients are intimately mixed together.
20 to 30 per cent of cullet (broken waste glass) is added to this mixture, which is then melted in tank furnaces with capacities of up to 1500 tons of material, or in pot furnaces containing a number of pots, each holding up to about 2 tons of material.
First, the fluxes, e.g., soda and the cullet added to the mixture, are melted.
The melting soda forms low-melting alkali silicates with the sand; these silicates enter into further reaction with the high-melting constituents and form the final glass melt. The carbon dioxide of the carbonates is expelled during melting and also at the end of the melting process, when the temperature is raised somewhat. Thereafter the temperature is reduced from the 1400°-1500° C, at which melting is carried out, to a temperature of 900°-1200° C.
Undesirable discoloration of the glass is removed in various ways, e.g., by addition of manganese dioxide, antimony oxide and arsenic. Coloured glass is produced by the addition of metallic oxides (iron, copper, manganese, chromium, etc). Glass melting furnaces are heated with gas or oil. The gas and the combustion air are passed through a heat exchanger; this raises their temperature before combustion takes place in the furnace (regenerative furnaces). Depending on the composition, the thickly liquid melted glass is formed to the required shapes by casting, rolling, drawing, moulding, blowing, spinning or pressing, either with or without blowing.
These processes are generally applied by machines. Hand forming processes, usually in conjunction with blowing with blowpipes, are now relatively little used. After forming has been done, it is most essential that cooling be correctly applied, so as to keep the glass as free as possible from stresses.
The sheet glass, rolled glass, pressed glass, hollow glassware, etc can be further worked and manufactured by cutting, drilling, milling, cementing, welding, bending, etching, grinding, engraving, polishing, enamelling, etc
Moores Glass is a specialist in glass manufacture. The glass is created to the highest standards. As an Industrial Glassware Manufacturer the glass createdis of the highest quality as it is used in many precision applications.