B 270^® - Superwite

Special Properties

• High transmittance for visible wavelengths
• Crystal clear and colorless appearance
• High-purity glass composition
• Excellent stability against solarization effects
• Very low visible aging when exposed to sunlight
• Fire-polished glass surfaces

Typical Applications

• Coating substrates
• LCD cover glass
• Touch panels
• Image forming optics
• Chip masks
• Optical windows
• Laboratory applications
• Glass substrates for mirror coatings
• Blanks for lenses and glasses

Related glass types

• N-BK7
  (Optical glass)
• BOROFLOAT^® 33
  (Borosilicate glass)
• Selected float glass
  (Premium quality soda-lime thin glass)

Request for Quotation

Partially available in 48 h Express-Service
(see table for 48h availability)

B 270^® - Superwite is a universal, economically priced quality glass with high transparency for visible and near-infrared light. The SCHOTT glass has a colorless crystal-clear appearance. It is very stable to the solarization effects that usually occur when a material continuously is exposed to the sun or UV light. When other glass materials begin to change their color, B 270^® stays white and clear. B 270^® is available as drawn glass, fire-polished sheet glass, or unpolished raw glass ingots. B 270^® as sheet-glass exists at many standard thicknesses. For applications where surface quality and waviness are not crucial, B270® can work without further treatment. However, to meet the requirements of more demanding optical applications, B 270^® sheet glass materials should be mechanically ground and optically polished. Grinding and polishing make it possible to use B 270^® for more demanding optics while keeping costs low.

In addition to B 270^®, the new B 270^® i is now available. The improved glass composition offers better chemical resistance, which primarily allows using the material for selected biotechnology applications. All other physical properties remain the same.

To get a quote for windows or substrates made of SCHOTT B 270^® Superwite glass with specific dimensions, please choose a thickness from the table in the specifications or click the button below.

 

Request for Quotation

Partially available in 48 h Express-Service

 

Specifications

Transmission spectrum
Transmission curve of B270^®

UV-Transmittance at 1,15 mm

UV-Transmission of B270^®

Standard Thicknesses

(Please click on a glass thickness to request a quote)

Thickness (mm)	Tolerance
0,90	±0,10	-
1,00	±0,10	✔
1,15	±0,15	✔
1,65	±0,15	✔
2,00	±0,20	✔
3,00	±0,20	-
4,00	±0,20	✔
5,00	±0,20	-
6,00	±0,30	-
8,00	±0,30	-
10,00	±0,40	-
The thicknesses marked with "✔" are also available within 48–h Express Service.
Occasionally other B270 Superwite strengths are available. If you cannot find the desired thickness here, please send us your inquiry.

Optical Properties

• Abbe numbers:
  • v_e = 58,3 +/-0,6
  • v_d = 58,5

Refractive Index (20 °C)
Description	Wavelength (nm)	Refractive Index
ng	436	1,5341
nF'	480	1,5297
nF	486	1,5292
ne	546	1,5251
nd	587,5	1,5230
nD	589,3	1,5229
nC'	644	1,5207
nC	656	1,5203

Mechanical Properties

• Density: 2,55 g/cm³
• Young's modulus E: 71,5 kN/mm²
• Poisson's ratio μ: 0,219
• Torsion modulus G: 29,3 kN/mm²
• Knoop hardness HK₁₀₀: 542

Thermal Properties

• Coefficient of mean linear thermal expansion
  (static measurement):
  • 9,4 x 10^-6/K (20-300°C)
  • 9,0 x 10^-6/K (20-200°C)
  • 8,2 x 10^-6/K (20-100°C)
• Viscosities:
  • Working Point (10⁴ dPa): 1033°C
  • Softening Point (10^7,6 dPa): 724°C
  • Annealing Point (10¹³ dPa): 541°C
  • Strain Point (10^14,5 dPa): 511°C
• Transformation temperature Tg: 533°C
• Heat conductivity (W/(m x K):
  • 0,92 (24,5°C)
  • 1,01 (89°C)
  • 1,08 (127°C)
  • 1,15 (167°C)

Chemical Properties

(not valid for B270^® i-type)

• Hydrolytic resistance according to DIN ISO 719:
  • Hydrolytic Class HGB 3
  • Equivalent of alkali (Na₂O) per g of glass grains:
    170 μg/g
• Acid resistance according to DIN 12 116:
  • Acid Class 2
  • Half surface weight loss after 6 h:
    1,4 mg/dm²
• Alkali resistance according to DIN ISO 695:
  • Alkali Class A2
  • Surface weight loss after 3 h:
    140 mg/dm²

Electrical Properties

• Dielectric constant ε_r: 7,0 (1 MHz)
• Dielectric Loss tangent (tan δ): 30 x 10^-4 (1 MHz)
• Specific DC-Volume Resistivity ρ_D (Ω x cm):
  • 10⁹ (250°C)
  • 1,6 x 10⁷ (350°C)
  • 2,0 x 10⁶ (400°C)
• Temperature Tk 100: 301°C
  (for volume resistivity of 10⁸ Ω x cm)

All given details and specifications are mean reference values and are not guaranteed. Also, please consider our "Notes on technical specifications".

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