Glass is an amorphous (non-crystal) material. It is a transparent material characteristic of rather good optical properties and usually conductive to all visible spectrum of light as well as a part of UV and IR spectrum (subject to glass type it might be impervious to UV rays, etc.). Nowadays glass is used in many spheres starting with window glasses and ending with glass bottles or pieces of art. We should not forget spectacles as well – they are manufactured using glass or variations thereof (silicate glass, borosilicate glass, acrylic glass, aluminium oxide nitrite, etc.)
Ordinary household glass mostly consists of silicon dioxide (quartz crystals or quartz sand). Boiling point of silicon dioxide is very high and reaches approximately 2300°C, such high temperatures impede glass production, therefore, this temperature is reduced to 1000°C through application of chemical ingredients such as sodium carbonate (soda), furthermore, if soda is added to the mixture, it must be complemented with calcium oxide which makes the mixture water-insoluble.
If flat glass is produced, the melted glass mass is passed under a certain amount of rollers which form sheets out of a viscous mass, they are cooled rather soon, therefore, optically regular, transparent sheets are obtained at the end of production.
Glass is interesting for many qualities thereof and one of its qualities is continuous “flow” thereof, glass is not a completely solid material, therefore, it gradually “flows” down under the impact of gravity towards the direction of gravity, therefore, windows of old buildings tend to be a bit thinner on top in comparison with the bottom, this process is very slow and invisible to the naked eye, it continues for many years. Scientists still disagree as to whether glass is a liquid or a crystalline material.
