Johnson Test Papers’ Grade 354 filter papers are among the fastest filter papers in the Johnson Test Papers ashless range. This gravimetric filter is well suited for quantitative analysis of soil and air. Extremely low ash content (0.007% ash maximum) Intermediate pore size of 12-15 µm Filtration speed of 10 seconds according to DIN 53137 Commonly used for routine air pollution analysis and soil pollution analysis Johnson Test Papers’ quantitative paper comes in a variety of particle retentions, filtration speeds, and filter thicknesses to provide you with the appropriate filter for your precipitate. Also see our hardened ashless grades for analysis requiring the use of strong acids or bases.