Whatman Grade 50 quantitative hardened low ash filter paper is highly glazed to enable recrystallization of very fine precipitates using Büchner funnel or Hirsch funnel filtration.

• Thinner filter design (average thickness 115 µm) than most Büchner filter papers
• Nominal particle retention of 2.7 µm
• Slow flow rates (Herzberg filtration speed 2685 s)
• High purity and low ash content (0.015% ash maximum)
• Acid-treated for high wet-strength and chemical resistance
• Hardened to minimize fiber shredding

This hard, very thin, high wet-strength Grade 50 quantitative filter paper withstands wet handling and precipitate removal by scraping. With very minimal fiber shedding, they are an especially good choice for use as carriers in integrated circuits.

Whatman low ash hardened filter paper for quantitative analysis is available in three grades. All three are designed for use in gravity and vacuum suction filtration in Buchner and Hirsch funnels. Grade 50 is also available in Smear Tab format for wipe testing, such as surface testing for radionuclide contamination.