See Inspection Penetrants POST-EMULSIFICATION PENETRANT A type of penetrant containing no emulsifier but which is cleaned from a surface with water after applying an emulsifier as a separate step. Often abbreviated as P.E. See Post Emulsification Penetrant Test. QUALIFIED PRODUCTS LIST (QPL) The US Government tests and approves inspection penetrants and publishes a Qualified Products List. At present this is SAE AMS 2644C

The ability of a product to seek all areas of the surface sprayed, usually refers to a lubricant's ability to thin out sufficiently to cover contacting metal surfaces. To penetrate.

Having power to enter or pierce; penetrating; sharp; subtile; as, penetrant cold.

A fluid (usually a liquid but can be a gas) which possesses unique properties that render it highly capable of entering small openings, a characteristic which makes this fluid especially suitable for use in the detection of surface discontinuities which may be present.

Process fluids that have penetrated the FRP liner or structural wall.

A penetrant is the cause for a service penetration firestop. Building codes can refer to mechanical and electrical penetrants as services.