Berliner Glas News and Events

Strengthening Process.

Increase Toughness, Control Fractures.

We make use of different strengthening processes in order to adapt glass, as a versatile, high-tech material, to its respective intended use.

Thermal tempering: Tempered safety glass (TSG)


thermally tempered glass - produced at Berliner Glas site in Schwaebisch Hall, Germany
Tempered safety glass consists of a single, specially thermally treated panel. The glass is heated to ca. 600 °C and then cooled suddenly. The center of the glass pulls back from the glass surface, which is being compressed. This process gives TSG an increased resistance to shocks and impacts. It is not sensitive to large changes in temperature and breaks into small, blunt pieces when exposed to extreme pressure. This reduces the risk of injury.


Thermal tempering: Semi-tempered glass (STG)

STG is exposed to a thermal tempering process just like TSG. However, the cooling process is slower, which results in less of a tension difference in the glass between the center and the surface. The resistance to bending lies somewhere between that of standard float glass and tempered safety glass. If broken, the resulting pieces resemble those of normal, non-hardened float glass.


Chemical strengthening: Chemically strengthened glass (CSG)

glass processing scheme - before and after hardening

If glass is exposed to a defined salt bath treatment, the resulting exchange of ions within a thin surface layer creates strong compressive stress that significantly improves the resistance properties of the glass. The chemical strengthening process is used primarily to strengthen thin glass up to 3 mm in thickness. The chemical strengthening process is ideal because the surface retains its flatness while also becoming more resistant to scratching.




Properties of tempered glasses

PropertiesFLOAT Glass UntreatedTSG Tempered Safety GlassSTG Semi Tempered GlassCSG Chemically Strength­ened Glass
Stone impact resistanceNo changeNo changeNo change~ +40 %
Flexural strength~ 45 N/mm²~ 120 N/mm²~ 70 N/mm²> 150 N/mm²
Tempera­ture shock resistance~ 40 K~ 150 K~ 100 K> 200 K
Cutting capabilityYesNoNoConditional
Appearance of fractureSplittingFriable structureSplittingSplitting
Appearance of fracture - Float glass untreated
Appearance of fracture - ESG Thermal tempered glass
Appearance of fracture - TVG Partially tempered glass
Appearance of fracture - CVG Chemically hardened glass

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Technical Glass and Touch Modules
Miranda Stender
Fon +49 791 93295-83
miranda.stender [at]
Technical Glass and Touch Modules
Fabian Schmidt
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Technical Glass and Touch Modules
Vera Hopfenziz
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specifications for chemical strengthening
Data sheet

Chemical Strengthening

(257 KB)

specifications for thermal tempering
Data sheet

Thermal Tempering

(609 KB)

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