A test programme was to be carried out to evaluate a series of additives for use in industrial metal cutting coolants for use initially on the turning, drilling and milling processes. These tests when they take the form of tool life tests are costly in time and material and where a shorter test can be reliably substituted for a life test, this is most desirable. To this end the grinding process was included in a pilot scheme to try to relate the grinding results to the drilling and turning results. Milling was not used in this pilot scheme. The grinding process has been very extensively studied at the College of Aeronautics during the past 10 years and a reliable method of evaluating the performance of grinding wheels and coolants has been developed and proved in a very wide range of industrial applications. The time required to evaluate a wheel or coolant sample is approximately 1 hour and the material consumed would be a few ounces in weight, hence, the desire to interpret coolant efficiency for the metal cutting processes from tests carried out using the controlled grinding process. (See ref. 1).