Ahlstrom’s qualitative grades of filter paper are, by definition, recommended for use in analytical methods, which determine or identify particulate constituents of a mixture irrespective of the amount present. Qualitative filter papers are often used in routine separation work that still requires high purity and consistent performance. Ahlstrom 950: 2.0µm – Slow Speed. This slow flow rate grade with very good retention is used in the filtration of fine precipitates and super phosphates. Ahlstrom 950 is also recommended for boiler water analysis applications and gas filtration.