Metrology Glossary: Viscosity

What Is Viscosity?

Viscosity is a key property that quantifies a liquid’s resistance to flow, often described as its “thickness.” Viscosity primarily relies on the strength of molecular interactions within a liquid; liquids with stronger intermolecular forces exhibit higher viscosity. For example, honey has an intricate molecular structure and robust intermolecular bonds, which is why it flows more slowly than water, which has a simpler molecular composition and weaker interactions. Viscosity serves not only as a foundational principle in scientific and industrial contexts but also as a tool for comprehending the diverse behaviors of liquids in our environment.

Why is Viscosity Important?

Viscosity is a fundamental property with significant applications. In the lubricants industry, it governs friction and wear, with higher viscosity for heavier loads and lower for lighter loads. Food processing relies on viscosity for dough properties, sauce, and soup texture. Coatings, like paints, inks, and adhesives, need viscosity for uniform application. Pharmaceuticals use viscosity for drug absorption in formulations like oral suspensions and gels. Personal care products such as lotions and shampoos depend on viscosity for spread ability and consistency. In industrial processes, viscosity controls fluid flow, optimizes product quality, and ensures efficiency, vital in fields from oil refining to polymer manufacturing.