EXPLANATION
These test methods are used for evaluating and characterizing tars and pitches and as one element in establishing the uniformity of shipments or sources of supply. Since these test methods are empirical, strict adherence to all details of the procedures is necessary.
TEST SUMMARY
The sample is digested at 95° C for 25 min, then extracted with hot toluene in an alundum thimble. The extraction time is 18 h in Test Method ASTM D4072, and 3 h in Test Method ASTM D4312. The insoluble matter is dried and weighed.
TEST PRECISION
Toluene insolubles determined by Test Method ASTM D4312 are higher by an average of about 1 percentage point compared to the value obtained by Test Method ASTM D4072.