Neutralization number

Also called neut number, an indication of the acidity or alkalinity of an oil; the number is the weight in milligrams of the amount of acid (hydrochloric acid [HCI]) or base (potassium hydroxide [KOH] required to neutralize one gram of the oil, in accordance with test method ASTM D 664 (potentiometric method) or ASTM D 974 9 colorimetric method).