Thanks to the tempering process, changes in internal stresses are made in the glass structure, resulting in an increase in bending strength. Glass is no longer so fragile and is often used in construction, interior design, furniture, industrial production of equipment. Tempered glass is abbreviated ESG, and thermally strengthened glass is abbreviated TVG / so-called. halfhart.
Hardening glass involves heating the glass to a high temperature (about 700°C) and rapidly cooling it in a stream of compressed air, resulting in compressive stresses in the surface layer, which significantly increases the strength of the glass.
Tempered glass has higher elasticity and mechanical and thermal strength than annealed float glass. It is safer because when broken it shatters into small non-injuring pieces (annealed glass shatters into dangerous needles).
Use of tempered glass:

- Monolithic glass (single flat and curved): partitions, wall cladding, doors, glazing, shower enclosures, table tops, glass shelves, furniture glass
- used in laminates: canopies, glass canopies, balustrades and railings, safety partitions, elevator shafts, floors and ceilings, roofs
- used in laminates and subjected to additional technological processes: floors, landings and stairs with anti-slip, balustrades with UV printing or painted
Limitations of glass processing after tempering
Already tempered glass is not subjected to further hard processing (such as cutting, drilling, edge grinding) – this is associated with a high risk of damaging the format or permanently weakening it. Nevertheless, the glass already tempered can be:
- sand
- imprint
- paint with water-based paint
Anisotropy
is a physical feature of ESG tempered glass – it consists of colored spots that become visible under polarized light.
In the process of tempering glass, zones of different stresses appear in its cross-section, which cause double refraction of light rays in the glass. If soda-lime-silicate glass (ESG or TVG) is observed under polarized light, the stress fields are visible as gray or colored areas, darker mottling or bands on the surface of the glass. Stress zones and anisotropy effects are thus due to the glass tempering process. They are visible at specific angles and in specific installation situations. Changing the angle of looking at a particular area of glass causes this phenomenon to disappear.
Anisotropy, according to current technical guidelines and European standard EN 12150, is considered a physical characteristic of tempered glass and is in no way a defect in the glass.
HALF TEMPERED GLASS TVG

TVG semi-tempered glass is distinguished from ESG tempered glass by the type of crack network that is formed when the glass sheet is destroyed. The nature of the crack means that the panel mounted in the frame remains in the frame after destruction, which protects against injury.
This makes TVG glass an interesting alternative to ESG tempered glass.
TVG glass is not classified as safety glass.
Type processing | Thickness glazing [mm] | Dimension minimum [mm] | Dimension maximal Float | Dimension maximal Low-E | Standard |
---|---|---|---|---|---|
ESG | 2,8 | 200 x 450 | 1600 x 2100 | 1300 x 2100 | EN 12150-1 |
ESG | 3,15 | 100 x 250 | 1600 x 2800 | 1500 x 2300 | EN 12150-1 |
ESG | 4 | 100 x 250 | 1800 x 2800 | 1800 x 2800 | EN 12150-1 |
ESG | 5 | 100 x 250 | 2800 x 6000 | 2300 x 3800 | EN 12150-1 |
ESG | 6 – 19 | 100 x 250 | 2800 x 6000 | 2800 x 6000 | EN 12150-1 |
TVG | 2,8 – 12 | 200 x 450 | 2800 x 6000 | 2800 x 6000 | EN 12150-1 |
TVG | 2,8 – 10 | 200 x 450 | 2800 x 6000 | 2800 x 6000 | EN 12150-1 |
Dimensions of tempered glass (ESG) and semi-tempered glass (TVG)
We invite you to cooperate with our glass tempering plant.
We also carry out orders for entrusted glass.