This grade has finer particle retention than Grade 601 but with slightly lower filtration speed. Grade 642 also has higher absorption than Grade 601. It is used in general laboratory applications to retain particles above 2 µm in size. Grade 642 is also found in agricultural and environmental laboratories for plant growth trials, soil testing, and air analysis for monitoring specific contaminants and in the filtration of organic and sulfide precipitates.
Ahlstrom-Munksjö manufactures a full range of laboratory filter paper for use in the beer industry. Grade 642 is recommended for the WORT color test.