A new additive for water based metal cutting and grinding coolant comprises
a combination of soybean oil and surfactant, the surfactant being a
nonoxynol or alcohol based detergent that is biodegradable. The proportion
of soybean oil to surfactant is adjusted for metal cutting or grinding and
the proportion of additive to water is also adjusted for metal cutting or
grinding. A small amount of bacteriocide may be added to the additive to
avoid rancidity.
