Higher nominal particle retention rating (22 µm) than comparable Buchner funnel filter papers Fast filtration speed (Herzberg filtration speed 39 s) High purity (0.015% ash maximum) Acidtreated for high wetstrength and chemical resistance Hardened to minimize fiber shedding Whatman Grade 54 hardened low ash quantitative filter paper for Büchner funnel and Hirsch funnel filtration enables fast vacuum suction filtration for recrystallization applications. This hard, smooth, high wetstrength Grade 54 fast filter paper enables collection of coarse and gelatinous precipitates with minimal fiber shredding, even when wet. Whatman low ash hardened filter paper for quantitative analysis is available in three grades. All three are designed for use in gravity and vacuum suction filtration in Büchner and Hirsch funnels.