Ahlstrom manufactures a series of extremely high purity, acid washed filter papers designed for use in analytical and gravimetric analysis. The quantitative grades are manufactured from top quality cotton linters using ultra-pure, reverse-osmosis water and are further treated with dilute acid to remove any remaining organic and inorganic impurities. All quantitative grades are manufactured in a strictly controlled environment that ensures high uniformity and high purity from filter to filter. Quantitative analysis Low ash content 0.007% (Acid-wash treated) High wet-strength Consistent performance Custom cut Bulk packaging Hardened Ashless Grades (Ash 0.006%) These specially treated hardened ashless grades are available for critical quantitative analytical techniques requiring increased wet-strength and handling capacity. These high purity filter papers have a tough, smooth surface free of loose fibers and are ideal for collecting wet precipitates. Each grade offers a convenient combination of particle retention and flow rate and are generally used because of their high chemical resistance to strong acid and alkali. Ahlstrom 75: 2.0µm – Medium Speed This grade has medium flow rate and good particle retention and is most commonly used for applications requiring high chemical resistance to strong acid and alkali. Ahlstrom 75 is often used for filtering trace elements, collecting hydroxides after precipitation by strong alkalis and in the analysis of metals in acid and alkali solutions.