Hardened ashless filters (ash content approx. 0.003%), especially recommended for filtration applications requiring vacuum and pressure filtration, and for the use of acidic and alkaline solutions.

  • Made of super-refined cotton linters and cellulose
  • Acid-washed and free of minerals and metallic ions, ideal for the detection of metallic ions
  • Very high wet strength; easy to scrap off or wash off precipitates
  • Hardened by small quantities of nitrogen-containing resin, which does not introduce significant impurities into the filtrate
  • High resistance to aggressive chemical components, like sulphuric and nitric acids (up to 40 % at 50 ° Celsius) and alkalis (up to 10 % at 20 ° Celsius)
  • For analytical applications, routine quantitative and /or gravimetric procedures


Grade SampleSpeedRetention rate* [µm]Filtration Herzberg (s) ThicknessWeight [g/m²]
B15540 Fine crystalline precipitates Medium 4-12 170 0.16 90
B15542 Very fine crystalline precipitates Slow ? 2 600** 0.14 90

* Approximate values, ** Measured with 100mm water column instead of 50 mm