What instrument measures viscosity for spray painting?

• A. Viscosimeter
• B. Hydrometer
• C. Caliper
• D. Refractometer

Answer: (A)

Viscosity is a fluid’s resistance to flow, which directly affects how paint behaves when sprayed. To measure this property, you use a viscometer (viscosimeter). It gauges how thick or thin the paint is by how easily it flows under a known force or shear, giving a viscosity value that helps you predict spray performance and atomization.

In practice, spray painters often use a practical viscometer such as a Zahn cup, which times how long a fixed amount of paint takes to flow through a small orifice. That flow time correlates with viscosity and with how the paint will perform in spray equipment. The other tools measure completely different properties: a hydrometer checks density, a caliper measures dimensions, and a refractometer measures refractive index.