Ahlstrom Grade 962 Fast Speed Wet-Strengthened Filter Paper. Wet-Strengthened Grades: Qualitative wet-strengthened grades are manufactured for applications using filter paper in a system or apparatus that operates under pressure or vacuum conditions. These systems require the use of extremely strong filter paper such as those in Ahlstrom's Binder Series. These grades contain a small amount of chemically stable, insoluble binding resin that strengthens the natural fiber-to-fiber bonds under wet conditions. Grades containing wood fibers or resins containing nitrogen, are not recommended for use in quantitative ashing techniques and in Kjeldahl estimations. Qualitative wet-strengthened filter papers are also used in industrial laboratories where technicians require a strong and economical filter paper with consistent quality and performance. Grade 962, 27 ¬µm - Fast Speed. This fast filtering qualitative wet-strengthened grade filter paper is a thinner version of Ahlstrom 961. Recommended for the filtration of coarse and gelatinous precipitates. The creped surface also offers higher surface area to maintain high filtration speed.