What is drying agent?
A drying agent is a final-rinse additive that lowers water surface tension so it sheets off the part instead of beading. Faster, more complete water removal means shorter dryer times, less spotting, and much less flash rust on freshly cleaned steel.
Also called: rinse aid, sheeting agent
Water on a clean metal surface beads because of its high surface tension. Each bead is a spot waiting to happen and a small reservoir of moisture that will sit against the metal. A drying agent breaks that, producing a thin continuous film that runs off under gravity.
Many industrial drying agents also carry a light corrosion inhibitor, which addresses the flash-rust window directly — the minutes between a hot rinse and a dry part are when bare steel is most vulnerable.
Dosage is low, typically well under 1%, and the agent must be low-foam or it will foam the rinse tank and defeat itself.
