Extremely high flow rate

• Excellent retention: captures coarse particles and gelatinous precipitates such as ferric hydroxide and aluminum hydroxide
• Fast filtration: useful for routine clean-up of biological fluids or organic extracts during analysis

Grade 4 Qualitative Filter Papers (20-25 µm particle retention) are available in a variety of sizes and formats including circles, sheets, and rolls. They are also available as prepleated filters, which give improved flow rate and increased loading capacity compared to equivalent flat filters.

How well do you know your filter paper grades and why you use them? To find out, read our blog Back to Basics Part 1: A Guide to Types of Whatman Filter Paper Grades. Ready for more? Read our 6-part blog series Whatman paper filtration 101 or our complete lab filtration blog.