Ahlstrom* Qualitative Grade Filters

Grade 237: 3 µm
This high absorbancy grade is twice as thick at grade 642 with similar particle retention. The superior absorbency offers excellent performance when used as a sample carrier. The extra thickness gives higher wet strength and loading capacity, enabling more precipitate to be held without clogging the filter. Highly suitable for use in Buchner funnels and for dye filtration.
Grade 601: 2.5 µm
Medium flow rate and retention. High purity (100% cotton). For air pollution testing, aluminum phosphate, barium carbonate, lead chromate, beryllium hydroxide.
Grade 609: 3 µm
This grade is an evolution of grade 613 for the beer industry. this is a filter paper with an exremely low iron and nitrogen content for the analysis of protein in beer.
Grade 610: 1.5 µm
Slow flow rate for fine retention. High purity (100% cotton). For water analysis, biological products, fine precipitates, used Buchner funnels.
Grade 613: 6 µm
Medium flow rate and retention. Strong general purpose filter, useful in Buchner funnels, for barium carbonate, lead chromate, beryllium hydroxide. Commonly used in student labs.
Grade 615: 25 µm
Fast filtering, rough surface. For aluminum ferric and magnesium hydroxides, insolubles, iron ore.
Grade 617: 35 µm
Very fast filtering general purpose filter for coarse and gelatinous materials, oils, resin solutions.
Grade 631: 10 µm
Fast filtering. Coarse surface. For air monitoring, gas filtration, ferric and magnesium hydroxides, insolubles.
Grade 642: 2 µm
Medium flow rate, good retention. High capacity. High purity (100% cotton). High absorption. Used in agricultural labs, air analysis, filtration of organic and sulfide precipitations.
Grade 8613: 4 µm
Designed for the sugar industry, this grade has a smooth black finish for use in applications requiring visual examination of particles.