Grade 40: 8 µm. General purpose ashless filter paper with medium speed and retention. For gravimetric analysis of numerous components in cements, clays, iron and steel products, as a primary filter for separating solid matter from aqueous extracts in general soil analysis, quantitative determination of sediments in milk and as a pure analytical grade clean-up filter for solutions prior to AA spectrometry. Also as a high-purity filter in the collection of trace elements and radionuclides from the atmosphere.- Properties: medium.- Ash content: 0.007 %.- Thickness: 210 µm.- Weight: 95 g / m2.- Filtration time acc. to Herzberg: 340 s.