A widely used standard grade filter paper for routine applications with medium retention and flow rate.

Slightly more retentive than Grade 1 with a corresponding increase in filtration time (i.e., slightly slower filtration speed).

A standard grade filter used in qualitative analytical techniques to determine and identify materials. For use in büchner funnels.

Fast flow & retention of coarse precipitates

Grade 44: 3 μm
Thin version of Grade 42 retaining very fine particles .

Intermediate in retention between Grade 40 and 41, and twice as fast as Grade 40