These filter papers withstand normal use in Buchner funnels or other devices under suction or moderate pressure. Fine crystalline precipitates (less than 5 µm) are retained. ASTM initial filtration speed is 90 seconds. Loading capacity is the highest. Slightly grained surface. 1.1 mg per 12.5 cm circle ash content. (For cost savings, see Ahlstrom equivalent, 446-300-02 Series)