From the physico-chemical view is glass a cooled and frozen melt. It consists of differential composition and is not structured crystalline, but amorphous homogeneous.


Glass includes the following characteristics:

  • Density/Heat Expansion
  • Mechanical Characteristics
  • Chemical Characteristics
  • Optical Characteristics

1. Density/Heat Expansion

The density of glass lies between 2,2 g/cm³ and 3,0 g/cm³ and at special glasses at 8 g/cm³.

The heat expansion of glass influences the thermal shock resistance. A glass with a lower thermal expansion co-efficient like for example borosilicate glass has a high heat resistance and thermal shock resistance.

2. Mechanical Characteristics

Glass is a hard and don't allow deformations via beats and hits. The resistance  of glass is minimised by injuries of the surface.

A glass surface which stands under compression strength, increased the  compressive resistance. 

Glass gets soft and mouldable between a temperature of 500 and 800°C. At a temperature of 1000°C it can be formed and will become hardened after cool down because of the addition of calcium carbonate.

The material glass has also a low electric and thermal conductivity.

3. Chemical Characteristics

Glass is resistant compared to the many materials, however hydrofluoric acid and alkaline glazes dissolve it. Water is able to attack glass, but only within longer periods and cause decomposition and lixiviation.

Glass is odourless and tasteless because it consists only of inorganic materials. If glass is used for example as packaging material for food, will occur no connection between the glass and its content because of the neutrality of glass.

Glass is able to keep its shape at high temperatures. So you can take this characteristic for example at the cleaning process of glass bottles to kill germs and can pass detergents up. Therefore glass is environmentally friendly and suitable as packaging material.

4. Optical Characteristics

Glass has a high transmissibility for visible light (transparency), which results from the fact that there are no free electrons.

Additionally can glass reflect and refract light. In that optical characteristic lies the  aesthetic essence of glass.