ISO 6791:1981

Carbonaceous materials for the production of aluminium — Pitch for electrodes — Determination of contents of quinoline-insoluble material

Specifies a conventional gravimetric method for the determination. A test portion ist reated with quinoline in a beaker at 70 to 80 °C for 15 to 20 min. Then the dissolved test portion and the residue are brought to a Hartley funnel fitted with a filter pad, and are filtered. The washed and dried residue on the filter pad is weighed.