Paper is a general purpose filter grade. Crystalline precipitates larger than 11 µm are retained. Initial filtration speed (ASTM)* of 40 seconds. Surface is smooth and of normal hardness. May be used for gravity or low suction filtration. 0.6 mg of ash content per 12.5 cm circle. Also suitable for air pollution analysis and for gas filtration. (For cost savings, see Ahlstrom equivalent, 446-100-02 Series)

*Time for 100 ml clean (prefiltered) water to pass through a 15 cm quadrant folded circle.