ASTM D2764 Standard Test Method for Dimethylformamide-Insoluble (DMF-I) Content of Tar and Pitch
5. Apparatus
5.1 Filtering Crucible, porcelain, with fine-porosity bottom, 30 mL to 40 mL capacity, high form, maximum pore diameter 7 µm.

5.2 Filter Apparatus - Filter flask and tube with crucible adapter.

5.3 Sieves, U.S. Standard 600 µm (No. 30) and 250 µm (No. 60), conforming to Specification E11.

5.4 Water Bath, maintained at 203 °F to 212 °F (95 °C to 100 °C).

6. Reagents and Materials
6.1 Dimethylformamide, reagent grade, boiling range 4 °F (2 °C) including 307 °F (153 °C). Store over a suitable desiccant. Decant immediately before use. If necessary, filter through a plug of glass wool or absorbent cotton until optically clear.

6.2 Acetone, meeting Specification D329. (Warning - Flammable. Health hazard.)

6.3 Concentrated Hydrochloric Acid.

6.4 Celite Analytical Filter Aid (CAFA) - Dry to constant mass at 22 °F (105 °C) and store in tightly stoppered container.

NOTE 1 - Do not use any other grade of filtering medium because porosities differ.