This Whatman 18.5cm, grade 2, cellulose filter paper is used in qualitative analytical techniques to determine and identify materials. It is slightly more retentive (8µm) than Whatman Grade 1, with a corresponding increase in filtration time (i.e., slightly slower filtration speed). It is also more absorbent than Grade 1. In addition to general filtration in the 8 µm particle size range, the extra absorbency is utilized. For example, it holds soil nutrient in plant growth trials. Additionally, it is used for monitoring specific contaminants in the atmosphere and in soil testing. Retention: 8µm. Diameter: 18.5cm. 100/Pack. Whatman #: 1002-185.