is the method for obtaining a semi-quantitative estimate of the amount of trace water present in a finished lubricant. A portion of the lubricant sample is poured into a metal pan or dipper and heated as rapidly as possible. As the temperature approaches 100°C (212°F), one or more distinct pops or crackles will be heard, and foam will form on the surface if water is present. Results are reported as Dry, Light Trace, Trace, or Heavy Trace. Also called pop test or thermal transfer.

Also see Karl Fischer Reagent Method.