Whatman Grade 589/1 Black Ribbon Filters are the established standard in quantitative analysis for the filtration of coarse precipitates. Ashless filter paper with very high flow rate. Used for many quantitative standard methods esp. for gravimetric applications (e.g. determination of the ash content in foodstuffs) or for the Blaine test in the cement industry. Retention: 12-25¬µm. 100/pack.