Indispensable Glass Capillaries

A reliable supply of high-quality glass capillaries is essential for any research laboratory, and at WPI, we are committed to ensuring you always have the materials you need. Our extensive selection includes single-barrel, thin-wall, and multi-barrel glass capillary tubes, designed to meet the diverse demands of your research applications. Understanding the critical role these products play in your operations, we prioritize efficient processing to ensure that most orders ship within 48 hours. If you require custom capillaries that are not listed on our website, please contact us; we accommodate specialty orders and will make every effort to fulfill your specific requirements. Be sure to also explore ourcomprehensive line of pullers, designed to complement your capillary needs with precision and reliability.

Superior Cell Impalement

Septum Theta offers superior cell impalement. The natural bevel resulting from the prominent spear-like projection of the septum gives microelectrodes a sharp, spear-point tip. This style has lowa resistance for use as a single microelectrode, and it can be used to make superior double-tipped microelectrodes with low trans-tip coupling. The natural bevel of Septum Theta also significantly increases the effective tip cross-section. As supplied, the width of the septum is approximately 0.2 mm, and the wall thickness is approximately 0.2 mm.

  • Features

    • Quality borosilicate glass capillaries
    • Large variety available, including fire polished, filaments, thin wall, specialty glass and multi-barrel

  • Benefits

    • Superior pricing
    • Most glass orders ship within 48 hours

  • Applications

    • Microinjection
    • Electrophysiology
    • Patch clamp
    • Fluid Handling
    • Fire Polishing

Fire Polishing

Fire-Polished glass capillaries are easier to insert into microelectrode holders without damaging the gasket. More importantly, fire-polished glass won’t scratch the chloridized wire used in a recording electrode. Fire-polishing does not affect the glass’s mechanical or electrical properties.

Making Uniform, Reproducible Microelectrodes

Borosilicate glass capillaries: Close dimensional tolerances assure microelectrode uniformity and reproducibility. Capillaries are available in 1, 2, 3, 5 and 7-barrel configurations, complete range of single barrel thin-wall sizes and a variety of special configurations. Capillaries with filaments contain a solid filament fused to the inner wall, which speeds filling of electrodes. Capillaries with or without inner filaments are available for making microelectrodes in a wide range of diameters.

Filament Glass Capillaries

Single Barrel standard wall thickness capillaries are offered either with or without inner filaments for quick filling in a variety of lengths and diameters.

Thin Wall Glass Capillaries

Thin Wall single barrel capillaries are offered both with or without inner filaments.

Physical Properties of WPI Glass Capillaries

The physical properties of glass depend upon the chemical composition of the glass, as well as how the glass was manufactured. Glass has no set melting point, but four temperatures are of primary importance when discussing glass production.

  • Working Point - This is the temperature that the glass is soft enough to work. At this temperature, the glass viscosity is 104 poises.
  • Softening Point - At this temperature, glass deforms easily, even by forces of gravity. The glass viscosity is 107.6 poises.
  • Annealing Point - When glass reaches the annealing point and remains for a few minutes, many of the internal stresses of the glass formation are obviated. During the annealing process, the glass is heated to the annealing temperature and then allowed to cool at a controlled rate. Glass that is not annealed is prone to crack or shatter with minor temperature fluctuations or mechanical shocks.
  • Strain Point - When glass temperature remains at the strain point for several hours, the internal stresses are relieved. Stresses that remain in the glass after maintaining the strain point for a few hours are permanent.in the tables below, we detail some of common glass specifications.
Duran® Schott 8250 Schott AR-GLAS® Schott BORO-8330™ Corning 7800 Kimble N51A
WPI Usage
  • Pulled Glass PG-52151, PG-52165
  • Patch clamp glass capillaries
  • Patch clamp glass capillaries
  • WPI thin wall glass capillaries
  • Pre-pulled micropettes with TW in the Part #
  • Multi-barrel capillaries
  • Septum theta
  • Piggyback capillaries
  • Glass rods
  • Single barrel glass tubing
    (Part #: 1Bxxxx)
Density ρ 2.28 g/cm3 2.50 g/cm3 2.23 ± 0.02 g/cm3 2.33 g/cm3 2.33 g/cm3
Working Point - 104 dPa·s 1055°C 1040°C 1260°C 1140°C
Softening Point - 107.6 dPa·s 720°C 720ºC 825°C 789°C 785°C
Annealing Point - 1013 dPa·s 500°C 530°C 560°C 565°C 570°C
Strain Point 490°C 525°C 525°C 517°C 530°C
Thermal expansion (0–300°C) 5.0x10-6/K 9.1x10-6K-1 33x10-7cm/cm/°C 55x10-7 cm/cm/°C 55x10-7 cm/cm/°C
Young's Modulus 64x103 N/mm2 73x103 N/mm2 6.4x103 kg/mm2 7.2x103 kg/mm2 10.4x106 PSI
Poisson's Ratio 0.21 0.22 0.20
Dielectric Constant for
1 MHz at 25°C		 4.9 7.2 4.6 5.8
Dielectric Loss Factor
1 MHz 25°C		 22x10-4 70x10-4 2.6% 4.9%
Refractive Index 1.487 1.514 1.473 mm2/N 1.490 mm2/N 1.490 mm2/N
Temperature Limits 460°C (extreme service) 200°C (normal service)
Max. Thermal Shock 115°C
Visible Light Transmission
2 mm thickness		 91%
Specific Heat 25–175°C 0.204 g. cals/g. deg.
Thermal Conductivity 1.2 W/m/K (at 90°C) 1.1 W/m/K (at 90°C) 0.0026 cals/cm/cm2/sec/°C
Corning 7800 Schott BORO-8330™ Schott AR-GLAS®
SiO2 73% 81% 69%
B2O3 10% 13% 1%
Na2O 2% 3.5% 13%
Al2O3 7% 2% 4%
K2O 2% 0.5% 3%
BaO 2%
CaO 0.7% 5%
MgO 3%
Corning 7800 glass is a type I, class B borosilicate glass that conforms to federal specification DD-G54lb and ASTM E-438. This glass has the composition shown in the table (left).

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