Zawiercie Crystal Glass Factory Ltd.

About glass

General information

Glass is a hard, fragile and shapeless mass. The majority of the currently used glass is received through the heating of the mixture of sand, sodium and calcium within the temperature of about 1500 degrees Celsius. Certain clearing substances are also applied within the aforementioned process, which depending on the needs colour and remove colour from glass. After the mixture has melted the products are formed and then the whole substance is slowly cooled down (the process of glass de-stressing).

Each type of glass (packaging, window, vehicle, isolation, heat resistant, utility etc.) possess different chemical content. The name of the each type of glass depends on the ingredient of the following the silicate, which is applied within the given manufacturing process for instance: sodium glass, potassium glass, lead glass (also referred to as crystal glass).

Glass is a solid object, which with the application of the proper conditions transforms into the liquid state. Its crystallisation capability (the capability for the transfer from the solid into the liquid state) is subject to the decrease along with the decreasing temperature. The change of form takes place with the application of the continuous method, which means that glass does not immediately transform from the liquid into solid state, such as for instance: water into ice, but is subject to gradual cooling off, thus increasing its viscosity until it reaches the status of the solid form (also fragile). The aforementioned process is reversible, the fact which means that heated glass does not melt with the application of the same rate as, for instance, ice, but that it becomes soft and ductible thus decreasing its viscosity along with the increase of temperature until it reaches the liquid state.

Natural glass is of greenish colour, which is subject to iron oxides (which are considered to be sand pollutants). In order to obtain transparent glass, sand needs to be added with oxidisers as well as colour supplementing compounds. In order to obtain glass of special characteristics, proper additives are to be used. Crystal glass is obtained through the adding of lead compounds to standard glass (i.e. sodium-calcium glass), whereas heat resistant glass is created thanks to the enriching of the mixture with aluminium compounds.

Glass does not convey heat or electricity in a positive manner, since it is an insulating agent. It demonstrates large chemical resistance. It is also permits a lot of visible radiation (about 90%) and demonstrates large stress resistance, but on the contrary, small bending and stretching resistance, since it s fragile, resistant to the influence of atmosphere and the influence of acids.


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