What is capillary glass?

Capillary Glass

Capillary glass refers to a type of glass tubing characterized by its very small internal diameter, resembling the capillaries in the human circulatory system. These tubes exploit the capillary action phenomenon, where the adhesion between the liquid and the surface of the tube causes the liquid to climb up the tube, against the force of gravity. This property makes capillary glass tubes particularly useful in a variety of scientific and medical applications.


  • Medical Sampling: Used for drawing small blood samples due to their ability to draw up blood through capillary action.
  • Chromatography: Employed in chromatographic techniques for the separation of substances.
  • Microfluidics: Integral in the design of microfluidic devices for manipulating small volumes of fluids.
  • Thermometers: Used in the construction of capillary thermometers, where the expansion and contraction of a liquid can be observed.


Capillary glass tubes are manufactured using specialized glass drawing techniques that allow for precise control over the internal diameter and wall thickness. The process involves heating a preform of glass until it becomes malleable and then drawing it out to form long, thin tubes. The dimensions of the tube can be controlled with high precision, allowing for the production of capillary tubes with specific properties tailored to their intended use.


  • Precision: Allows for the precise control and manipulation of small volumes of liquid.
  • Versatility: Can be used in a wide range of applications across different fields.
  • Efficiency: Enables efficient sampling and testing with minimal waste.
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