What is surfactant?
A surfactant is a molecule that lowers the surface tension between two phases — typically water and oil. In cleaning chemistry surfactants let the bath wet the part, penetrate blind holes, lift oil films and hold them in suspension. Their type and cloud point determine how much a cleaner foams.
Also called: surface active agent, wetting agent
Surfactants are grouped by the charge on their water-loving head: anionic (negative), cationic (positive), non-ionic (uncharged) and amphoteric. Industrial degreasers lean heavily on non-ionics, which tolerate hard water and alkalinity and — critically — can be selected for low foam.
Non-ionic surfactants have a cloud point: the temperature above which they come out of solution and stop foaming. Choose one with a cloud point below the intended wash temperature and the cleaner runs low-foam in a spray washer. Choose one with a cloud point above it and the same cleaner foams the pump.
This is the single most useful thing to know when a spray washer starts cavitating: the problem is usually not dosage, it is that the bath is running below the cleaner's designed temperature window.
