This high absorbency grade is twice as thick as grade 642 with similar particle retention. The superior absorbency offers excellent performance when used as a sample carrier. The extra thickness gives higher wet strength and loading capacity, enabling more precipitate to be held without clogging the filter. Ahlstrom 237 is also highly suitable for use in Buchner funnels and for dye filtration.

Standard qualitative filter papers are suitable for quadrant folded or gravity flow applications. These grades contain a high level of alpha-cellulose that provides high purity but will weaken when wet. The inherent strength of standard (untreated) grades does not pose a problem when they are used in routine quadrant folded applications. We do not recommend these grades for use in vacuum work or when wet handling is required.