Sartorius qualitative filter papers are made of refined pulp and cotton linters with more than 95% alpha cellulose content. The ash content of these filter papers is < 0.1% and they are essentially used for qualitative analysis. Sartorius offers two categories of qualitative filter paper: those that are wet strengthened and those that are not wet strengthened. These filter papers are available as rolls, sheets, discs and folded filters. Special sizes can be cut upon request.