EXPLANATION
Lubricating greases can contain the lithium soap of hydroxy stearic acid or the sodium soap of various fatty acids as thickeners. The determination of total lithium or sodium is a measure of the amount of thickener in the grease. This test method uses flame photometry for this determination.
TEST SUMMARY
The sulfated ash (Test Method ASTM D874) of the grease sample is extracted with water and the lithium and sodium content of the resulting solution is determined by means of a suitable flame photometer.
TEST PRECISION
Where X is the average of determinations.
The bias of this test method has not been determined.