Viscosity tubes are used principally for direct comparisons to Gardner Viscosity Standards.

• With 0.65 mm wall thickness
• Tolerance level ID: ±0.025
• Viscosity tube is composed of soda-lime glass with flat-blottoms
• Score marks are measured from the center outside bottom of the tubes

Viscosity tubes are permanently marked with two score marks, at 100mm and 108mm heights. The score mark at 100 mm represents the filling level and the 108 mm score is used to fix the size of the air bubble in the tube by inserting a cork to this mark.

For bubble rate rise comparisons to Gardner Viscosity Standards, (10.65) it is equivalent to Gardner A tubes.