Definition
A calibrated cup with a precisely sized hole in the bottom, used to measure the viscosity (thickness) of a liquid such as paint or finish. The cup is dipped, filled, and lifted, and the time it takes for the liquid to drain through the hole is measured with a stopwatch. The result, expressed in seconds, indicates whether the liquid is at the correct consistency for spraying.
Plain English
A small metal cup with a hole in the bottom that technicians use to check whether paint is the right thickness. They time how long it takes to empty, and that time tells them if the paint is ready to spray.
Context Anchor
Seen in aircraft maintenance when mixing or checking paint, finish, adhesive, or other liquids that must flow correctly before use.
Derivation
Viscosity comes from the Latin viscum, meaning mistletoe or sticky birdlime made from its berries. The word came to describe how thick or 'sticky' a fluid is — how much it resists flowing. A viscosity cup, then, is simply a cup used to measure that resistance.
Why Pilots Care
Correct fluid thickness ensures paints and coatings adhere properly and provide the intended protection and finish on aircraft surfaces.
Analogy
It works a little like timing how fast syrup or water runs through the same small hole. The thicker liquid takes longer, and that time tells you something useful.
Grounding Statement
A thicker liquid drains more slowly from the cup; a thinner liquid drains more quickly.
Intuition Check
A viscosity cup is not a cup for measuring how much liquid you have. It is a tool for measuring how easily that liquid flows.
Example Sentence 1
Before spraying the topcoat, the technician used a viscosity cup and a stopwatch to confirm the paint drained in the time specified by the manufacturer.
Example Sentence 2
Before mixing the topcoat, she checked its consistency with the viscosity cup to avoid runs or orange peel.