What is it used for?
Determination of the levels of insoluble matter in a sample. Solid, or particulate contaminants such as soot can have a destructive effect on oil, especially when anti coagulant or dispersant packages fail.
How does it work?
The technique is used for the determination of insoluble matter (largely carbon) and utilises 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 – put simply, the higher the observed value, the darker the oil spot and therefore the more soot is present.
What do the results tell us?
The method is typically used as a trending tool for determining combustion-related soot in used crankcase oils – one-off results are of limited value.
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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