Ash-less for quantitative analysis . α- cellulose content of over 95%, ash content approx. 0.002%. Made of high-purity acid washed cotton linter pulp and cellulose mixed with a small quantity consolidating resin. Free of minerals and metal ions. High stability and resistance, very high wet strength. Deposits can be removed easily with no fibres. For analytical applications, routine quantitative and gravimetric methods. Highly recommended for vacuum and pressure filtration, determination of metal ions, and filtration of acidic and alkaline solutions. Resistant to sulphuric and nitric acids (up to 40% at 50 °C) and alkalis (up to 10% at 20 °C). Round filters hardened Type 1506 Medium filtration speed. Herzberg filtration time: 170 s. Surface weight: 90 g/m 2 . Retention range: 4-12 μm. Thickness: 0.16 mm.