GE Healthcare’s ashless grade are very pure filters suitable for a wide range of critical analytical filtration procedures. Hardened low ash grade papers are acid-treated to remove trace metals, produce high wet strength, and chemical resistance. The tough, smooth surface of these filters makes it easy to recover precipitates, rendering them particularly suitable for Büchner filtration. Hardened ashless grade filters combine acid-hardening with extremely low ash content, making them suitable for a wide range of critical filtration procedures. Whatman quantitative filter papers are designed for gravimetric analysis and the preparation of samples for instrumental analysis. They are available in three formats designed to meet your specific needs: ashless, hardened low ash, and hardened ashless.