Determination of the levels of insoluble matter in a sample. Solid, or particulate contaminants l soot can have a destructive effect on oil, especially when anti-coagulant or dispersant packages fail.
The technique is used for the determination of insoluble matter (largely carbon). Utilising the transmission of light through a drop of oil absorbed on chromatographic paper.
The optical density of the absorbed oil is measured using a transmission densitometer. The higher the observed value, the darker the oil spot and therefore the more soot is present.
The method is used as a trending tool for determining combustion-related soot in used crankcase oils.
The method only works if the insoluble matter in question is soot. Soot will absorb transmitted light, whereas metallic or silica-based debris will not.
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