The saponification number indicates the amount of potassium hydroxide (KOH) required to neutralise all free and combined acids as well as to crack/saponify the esters contained in 1g of a lubricant sample. As a result of the titration, the consumed amount of potassium hydroxide is indicated in mg. The unit is mg KOH/g lubricant. The term saponification is derived from the reaction carried out in earlier times for the production of household soap. In the lubricant industry, soap is the term used for metal salts of organic acids.