Quantitative Grade, Ashless
| Grade No. | Flowrate | Retention microns | Wet strength | Thickness, mm | Ash % | |
| 42 | Highly retentive for fine precipitates | Slow | 2.5 | Low* | 0.20 | 0.01 |
*Suitable for gravity or low suction filtration. Care must be taken to prevent rupture of the paper.