Equivalent to No. 41, grey label = black ribbon, fast filtration, smooth. Ashless filter papers are particularly suited for quantitative routine analysis and are manufactured from refined pulp and linters. They are acid-washed and have an extremely low ash content of < 0.01 %. The amount of α-cellulose is about 95 %. These filters are used specifically with suction filters. The elevated border safe- ly prevents sample to run past the edge of the filter. Residues won’t stick to the suction filter walls. Thus, the entire filter cake can be used for further analysis quickly and easily.