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.

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.