There are various quenching media such as water, oil, brine, molten salts, molten metal, still air or blasted air. Water and brine are the most drastic quenching mediums. To satisfactorily harden steel, water should be kept below 25°C (80°F) and continu- ally agitated during the quenching operation. Agitation of the cooling medium insures a more uniform and faster cooling action. Brine is faster, is more uniform, and is less affected by increases in temperature. Oil is used as a quenching medium in hardening operations. Molten salts or molten metals are high-temperature quench baths and are frequently used with interrupted or timed quenching. Air provides the mildest type of quench.