HITEGLA BLOG
Strength of different types of glass – overview of properties
Glass is an amorphous material whose mechanical properties depend on both its chemical composition and the method of processing. The basic parameter describing the mechanical resistance of glass is its bending and tensile strength, followed by hardness, impact resistance and thermal shock resistance.
Soda-lime glass (float)
Most commonly used in construction and window pane production. It is characterised by a bending strength of 30–90 MPa. It is brittle and susceptible to scratches, and its resistance to sudden temperature changes is usually 60–90°C.
Tempered soda-lime glass
It is produced by rapidly cooling the surface of heated soda-lime glass. This process creates compressive stresses in the material, which increases its bending strength to as much as 120-200 MPa, i.e. 4-5 times more than in float glass. An additional advantage is the way it breaks – it shatters into small, less dangerous fragments. Its thermal shock resistance is as high as 200–250°C.
Laminated soda-lime glass (VSG)
It consists of several panes of glass joined together with a polymer film (e.g. PVB). The mechanical strength of a single pane does not increase significantly compared to ordinary float glass, but thanks to the film, the glass remains intact after breaking. This is particularly important in terms of safety and burglary protection.
Borosilicate glass
Thanks to boron oxide additives, it has increased chemical and thermal resistance. Its mechanical strength ranges from 35 to 100 MPa, but its greatest advantage is its high resistance to thermal shock – up to 300–400°C, which makes it a material used in laboratories and kitchen equipment.
Quartz glass (fused silica)
It consists almost exclusively of SiO₂. It is characterised by very high resistance to temperature and thermal shock (even above 1000°C) and good dimensional stability. Its mechanical strength is similar to that of soda-lime glass (approx. 50–70 MPa), but its resistance to extreme environmental conditions is of key importance.
Summary
• Tempered glass has the highest mechanical strength.
• Quartz and borosilicate glass have the highest resistance to thermal shock.
• Laminated glass is the safest to use, as it retains its integrity after damage.
The choice of glass type therefore depends not only on mechanical strength, but also on requirements for safety, temperature resistance and chemical resistance.
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