Continental Trade Sp. z o. o.

Technical glass


Glass ceramics are obtained by controlled crystallization, usually caused by additives that become crystal seeds. This process, depending upon the additives can produce a range of materials with interesting (and sometimes surprising) properties. For example, you can get a glass ceramic with high resistance to thermal shock and completely transparent to applications, eg. as cooking utensils. Another combination of ingredients allows you to get material biochemically inactive, transparent, relatively soft for dental applications.

Glass ceramics are typically prepared in two steps. In the first step, glass is prepared in a standard thermal process. In the second step, the glass is cooled and re-heated above the glass transition temperature. This step is sometimes repeated (creating a third step). During these thermal processes, glass partially crystallizing in the interior. In most cases, to the base composition are added nucleating agents (eg. precious metals, fluorides, ZrO2, TiO2, P2O5, Cr2O3, or Fe2O3) to stimulate the crystallization process.

Less commonly used method is to provoke and controlling internal crystallization during the cooling phase of the molten liquid of high viscosity. This process is sometimes used to produce relatively coarse glass-ceramic used in the construction industry.

In contrast to classical and sintered  ceramics and is by nature free of porosity. Another useful feature is the high resistance to thermal shock and high temperature of operation. Glass ceramic has virtually zero coefficient of thermal expansion. Well transmits visible and infrared radiation.

Because of these properties, ceramic glass are used as heating plates, fireplace glass , radiator covers, etc.

Schott ROBAX®

Transparent glass-ceramic Schott ROBAX®

This glass is extremely heat resistant. The combination of good transmittance visible and infrared radiation (which we feel as heat) with a low coefficient of thermal expansion of glass make ROBAX excellent material for the manufacture of glass heating devices such as fireplaces or stoves.


  • high temperature resistance (up to 700 °C)
  • good transmittance of visible and infrared light
  • blocking ultraviolet radiation
  • excellent thermal shock resistance


  • windows in fireplaces and stoves
  • protective panels in heat radiators
  • UV protection
  • enclosures for high-power light sources
  • enclosures for infrared drying devices
Some propertiesTransmittance of ROBAX glass
Density 2,58 g/cm3 Full range
Modulus of elasticity (Young’s) 92 GPa
Poisson’s ratio 0,25
Coefficient of thermal expansion 0,0 ±0,5 10-6 /K
Max. working temperature:
- up to 5 hours 760 °C UV range
- up to 10 hours 710 °C
- up to 100 hours 660 °C
- up to 1000 hours 610 °C
- up to 5000 hours 560 °C

Transparent glass-ceramic Schott ZERODUR®

Zerodur® is non-porous material, very homogeneous, created in the controlled volume crystallization of the silica with the addition of lithium and aluminum. It is a glass with an extremely low coefficient of thermal expansion, which becomes zero or even negative in certain temperature ranges (see chart below). Another unique feature of this material is its unique uniformity (homogeneity). Even in large blocks Zerodur does not indicate disorders of mechanical, thermal or optical properties. High transmittance of radiation in the range of 400 nm to 2300 nm (see chart below) allows easy verification of the inner homogeneity.


  • extremely low coefficient of thermal expansion 
  • very high homogeneity of the material (thermal, mechanical and optical)
  • high permissible operating temperature
  • smooth surface (roughness < 1nm)
  • excellent chemical resistance


  • precision optics
  • precision measuring equipment
  • mirror substrate at large astronomical telescopes
  • substrate for X-rays telescopes
  • all applications where you need to minimize changes in shape with temperature changes.

Coefficient of thermal expansion

Thermal expansion of  ZERODUR 


Some propertiesTransmittance of ZERODUR glass
Density 2,53 g/cm3 Transmittance of ZERODUR glass
Modulus of elasticity (Young’s) 90,3 GPa
Poisson’s ratio 0,24
Coefficient of thermal expansion 0,0 ±0,1 10-6 /K
Thermal conductivity 1,46 W/(m K)
Max. working temperature: 600 °C

Hydrolytic resistance

   Acc.  ISO 719 (@ 98 °C): class HGB 1 

Alkali resistance

   Acc. ISO 10 629: class 1

Acid resistance
   Acc. ISO 8424: class 1

Dielectric properties

@ 25° C i 1 MHz: 
   Dielectric constant εr=7,4 


PYROCERAM® glass-ceramic

Is created by adding to the aluminosilcate glass crystallizing additives in the form of titanium oxide. The material suitable for machining and smoothing the surface by etching. Transmits visible radiation giving him a pale amber color. Has a low coefficient of thermal expansion, high thermal shock resistance and high working temperature.


  • windows for fireplaces and stoves,
  • glass in the microwave,
  • in architecture and lighting,
  • blocking ultraviolet radiation,
  • heat resistant cookware in the household.


Some propertiesTransmittance of PYROCERAM glass
Density 2,55 g/cm3 Transmittance of PYROCERAM
Young's modulus 94,3 GPa
Poisson ratio 0,25
Thermal expansion coefficient 0,0 ±0,3 10-7 /°C
Thermal shock 700°C
Max. working temperature:
- long term 700 °C
- temporary 800 °C

Chemical properties

Hydrolytic resistance
   Acc.  ISO 719 (@ 98 °C): class HGB 1 

Alkali resistance
   Acc. ISO 695: class 1

Acid resistance
   Acc. DIN 12 116: class 1

Dielectric properties

@ 25° C i 1 MHz: 
   Dielectric constant εr=8,1 


  • maximum sheet size: 2 005 mm x 1 100 mm
  • glass thickness: 3 mm, 4 mm or 5 mm (± 0,2 mm)


While every attempt has been made to verify the source of the information, no responsibility is accepted for accuracy of data.

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