Quantitative Ashless Grade Filter Paper and Hardened Low Ash Grade Filter Paper

Quantitative filter paper: ashless grade
Ashless quantitative filter paper is produced under strict control with high-quality cotton lint as raw material. These high-purity filter papers are ideal products for various important analysis and filtration steps; accurate results can be obtained for gravimetric analysis.

Grade 40: 8μm
It’s classic ashless filter paper with a wide range of uses (ash content <0.007%), with medium particle retention and flow rate. Typical applications include laboratory gravimetric analysis, such as gravimetric analysis of cement, clay, iron, and steel products; the filtration of the solution before the atomic absorption spectrophotometry, filtration in soil analysis, etc. It can also be used for high-purity filtration and collection of trace elements and radioactive elements in atmospheric monitoring.

Grade 41: 20-25μm
The ashless filter paper with the fastest flow rate (ash content <0.007%), is recommended for the analysis of large particles such as aluminum hydroxide or iron hydroxide or the filtration of gel deposits. In quantitative air pollution analysis, it can be used as an adsorbent when measuring gaseous compounds at high flow rates.

Grade 42: 2.5μm
HAWACH cellulose filter paper retains the smallest particles in the medium-speed filter paper. It is the standard filter paper for assessment and gravimetric analysis, and the ash content is <0.007%. It is often used for the analysis of fine particle deposits such as barium, partial tin, and carbon calcium.

Grade 43: 16μm
Its retention between No. 40 and No. 41 filter paper, the filtration speed is twice that of No. 40 filter paper, ash content <0.007%. It is commonly used for sample collection in food analysis, soil analysis, air pollution monitoring, and inorganic analysis in the construction industry, minerals, and iron and steel industries.

Grade 44: 3μm
No. 44 filter paper has lower ash content than other filter papers in this series. The efficiency of collecting particles is slightly lower than that of No. 42, but the flow rate is almost twice that of No. 42.

lab grade filter paper hawach-filter-papers-bio-42 hawach-filter-papers-bio-41

Quantitative filter paper: hardened low ash grade
For the hardened low ash grade, the ash content is between the qualitative grade and sh-free grade, with a tough and smooth surface making it easy to recover sediment. Such kind of filter paper is very suitable for Buchner funnel filtration. Other characteristics including high wet strength and chemical compatibility are similar to hardened ashless grades. There are three grades available, 2.7 μm, 7 μm, and 20-25 μm. Details are as follows:

Grade 50: 2.7 μm
As the thinnest kind of HAWACH filter paper with excellent particle retention and slow flow rate, it can retain very fine crystals and precipitates. No.50 filter paper is currently the designated standard filter paper for drilling fluid determination worldwide and is widely used in fluid laboratories for oil and gas extraction operations. In food analysis, it is combined with others to determine the fat content in meat products. It can be used in a three-piece funnel vacuum, quantitative filtration or Buchner funnel with its hardened surface preventing the fiber from falling off effectively. With very good wet strength, it can be scraped off in wet state. In the electronics industry, it is a carrier with almost no fiber shedding and is used in integrated circuits. It also provides a smear pattern for wiping tests (for example, surface tests for radionuclide contamination).

Grade 52: 7 μm
This kind of filter paper has a medium flow rate, medium retention capacity, and tough surface, which is suitable for conventional filtration.

Grade 54: 20-25 μm
This hardened low ash quantitative filter paper features high humidity and a fast flow rate. It is frequently used in colloidal precipitates filtration, like the thyl hydroxyquinine in feed and rapid vacuum filtration to remove hard-to-filter coarse particles.