GRADE 1507 FILTRATION: Hahnemühle 150 mm ashless and hardened filters (approx. 0.002%) are especially recommended for vacuum and pressure filtration, and for the use of acidic and alkaline solutions due to high resistance to aggressive chemical components, like sulphuric and nitric acids (up to 40% at 50°C) and alkalis (up to 10% at 20°C) HARDENED FILTER: Our hardened low ash filters demonstrate high wet strength and chemical resistance and have a hardened and highly-glazed surface that can withstand wet handling and scraping. They are hardened by small quantities of nitrogen-containing resin, which does not bleed significant impurities into the filtrate. SUPERIOR PERFORMANCE: Quantitative filter paper with <2 μm pore size has a slow flow rate that makes it suitable for capturing very fine precipitates. These filter circles are composed of highly pure super-refined cotton linters and 95% α-cellulose content, which provides the filter paper with high stability and durability. NEUTRALISED: Lab filter papers are acid-washed and rinsed with water to neutralize any acidic substances present, resulting in a filter paper that is free of minerals and metallic ions. This makes it ideal for the detection of metallic ions. APPLICATIONS: Quantitative filter papers discs are perfect for gravimetric analysis of fine metals like barium and lead sulphate, nickel and tin sulphide, oxalate and calcium fluoride. Particularly suitable for Büchner filtration where the tough smooth surface of the filter makes it easy to recover precipitates.