A Viscosity Bath is a highly specialized temperature-controlled water or oil bath designed primarily for the determination of viscosity in liquids, especially petroleum products, lubricants, chemicals, and pharmaceuticals. The bath maintains a stable temperature environment which is critical for accurate and repeatable viscosity measurements, as viscosity is highly sensitive to temperature changes.

These baths are typically used in conjunction with viscometers, such as Ubbelohde, Cannon-Fenske, or Ostwald viscometers, where the time taken for a liquid to flow through a capillary under the influence of gravity is measured. The bath provides a uniform thermal environment to ensure that the sample maintains a constant temperature during the test, which is essential for precise results.

Viscosity Baths come with transparent glass windows (often double-walled) or open-top designs for easy observation of the viscometers inside. Most modern units feature digital PID temperature controllers, over-temperature protection, circulation pumps for even heat distribution, and are compliant with industry standards such as ASTM D445, D446, and ISO 3104.

They are widely used in quality control laboratories, research institutes, petrochemical testing labs, food and beverage industries, and academic institutions where fluid behavior analysis is important for product development and standardization.