TLG® Ashless Quantitative Filter Papers No.42 have the finest particle retention, making them suitable for analysis of very small particles. These filter papers are useful in processes requiring ashing and the preparation of gravimetric precipitates. Commonly used as a calcium carbonate filter for analysis in the cement industry. SPECIFICATIONS Material: High Quality Cotton Linters Porosity: Fine Particle Retention in Liquid: 2.5µm Herzberg Filtration Speed: 2040sec/100mL (or ASTM: 240sec) Nominal Thickness: 180 ± 10µm Nominal Weight: 100g/m² Nominal Ash Content : 0.007% Package Size: 100 Pieces