Whatman No. 54

Of the hardened grades, this has the highest filtration speed. 10 seconds is the initial filtration speed. For use with coarse particles or gelatinous precipitates. Loading capacity is normal. Retention rating is 20-25 µm. Resists chemicals. High wet strength. Smooth, hard surface. 0.28 mg ash content per 12.5 cm circle. (For cost savings, see Ahlstrom equivalent, 445-300-02 Series)