Low Tg Glass for Precision Molding

Product Information

Low transformation temperatures suitable for precision molding

Precision molding is one of the state-of-the-art-technologies for the volume production of complex lenses (e. g. aspheres), for various applications.

SCHOTT offers several optical glasses specifically developed for precision molding – the low Tg glasses, such as P-SF68, P-SK57Q1, P-SK58A and P-BK7.

Low Tg glasses have a glass transformation temperature suitable for precision molding and a special glass composition to decrease the tendency for devitrification and to reduce the reaction with mold materials within the molding temperature range.

During precision glass molding, a polished or fire polished preform is shaped into a final geometry, while conserving its surface quality. The typical temperature range for the molding process is between 500 °C and 700 °C, enabling the extension of the operating lifetime of the mold material and a significant time reduction of the press process.

SCHOTT low Tg glasses are provided in the form of optical glass rods as well as ball lenses in different formats.


  • Low transformation temperatures, mostly below 550 °C, to increase lifetime of molds and to reduce process time
  • Low tendency for chemical interaction between glass constituents and mold materials within the molding temperature range
  • Tight optical tolerance
  • Wide range of dimensions
  • Various forms of supply
  • Application support

Supply Forms

Low Tg glass for precision molding is available as:
Supply Forms*
Optical glass rods
  • various shapes
  • various surface qualities

Diameter: < 1 mm - 7.5 mm; length: up to 1,000 mm
Diameter: > 7.5 mm - 12.5 mm; length: up to 140 mm
Ball lenses
  • different formats
Diameter: 0.8 mm - 14 mm

* Other supply forms and dimensions upon request. Please contact us.

Technical Information

Materials used

Low Tg Optical Glasses
SCHOTT North America, Inc.
400 York Avenue
Duryea, PA 18642
E-Mail to SCHOTT570-457-7485
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