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 offers a complete range of low ash filter papers for general laboratory work that provides you with the correct combination of particle retention, filtration speed, loading capacity and wet-strength. All our qualitative grades consist of > 95% super refined a-cellulose and linter fibers. For quantitative analysis. Low ash content 0.06%. Untreated, high wet-strength, 2.5¬µm ‚Äì medium speed. Consistent performance. Wet-strengthened grades available. Custom cut with bulk packaging.