SCHOTT BOROFLOAT® 33

Borosilicate glass

Description

SCHOTT BOROFLOAT® 33 is a borosilicate float glass with excellent thermal resistance, low thermal expansion, chemical durability and good optical transmission for demanding technical glass applications.

Attribute	Value
Process	Precision cutting; CNC fabrication; edging; drilling; screen printing; optical coating; heat strengthening where applicable
Features	Low thermal expansion; high temperature resistance; chemical durability; good transmission; low density
Substrate(s)	Borosilicate glass
Color	Clear, slightly green tint depending thickness
Transmission Range (nm)	400 - 2700 nm
Refractive Index	1.471
Sheet Length - Max (mm)	2300mm
Sheet Width - Max (mm)	1700mm
Knoop's Hardness kg/mm²	480
Softening Point °C	820°C
Annealing Point °C	560°C
Strain Point °C	518°C
Transformation Temperature (Tg) °C	525
CTE (Coefficient of thermal expansion) α in 10-6 · K-1 (20°C; 300°C)	3.25
Specific Heat Capacity (Cₚ) kJ/(kg·K) (20–100°C)	2300
Thermal Conductivity (ʎ) W/(m·K) (90°C)	1.25
Photoelastic Constant (nm/cm/MPA)	40
Can be strengthened?	Yes

Advantages

good optical transmission
heat resistance
high chemical resistance
low density
Low thermal expansion

Applications

filters
lighting windows
medical and analytical devices
mirrors
Optical windows
viewports

Industries

Defense & Avionics
Industrial
Lighting
Medical & Biomedical
Photonics & Electro-Optics