TLG® Qualitative Filter Papers No.4 have a very fast filtering speed, making them ideal for used in filtration of coarse particles during air pollution monitoring tests or the retention of gelatinous precipitates. These filter papers are suitable also when routine clean-up of biological fluids or analysis of organic extracts are required. SPECIFICATION Material: Cellulose Porosity: Coarse Surface: Smooth Particle Retention in Liquid: 25µm Herzberg Filtration Speed: 50sec/100mL (or ASTM: 12sec) Nominal Thickness: 200 ± 10µm Nominal Weight: 90g/m² Nominal Ash Content : 0.06% Package Size: 100 Pieces