Whatman Grade 1 is the most widely used filter paper for routine applications with medium retention (11 µm) and flow rate. Extended range of sizes includes 10mm to 500mm diameter circles and 460mm x 570mm sheets. This filter is also available in the Whatman FilterCup™. This is a convenient, disposable 70mm filter funnel with a 250mL capacity molded from polypropylene with an integral, heat bonded filter. This grade covers a wide range of laboratory applications and is frequently used for clarifying liquids. Traditionally the grade is used in qualitative analytical separations for precipitates such as lead sulfate, calcium oxalate (hot), and calcium carbonate. In agriculture, it is used for soil analysis and seed testing procedures. In the food industry, Grade 1 is used for numerous routine techniques to separate solid foodstuffs from associated liquid or extracting liquid and is widely used in education for teaching simple qualitative analytical separations. In air pollution monitoring, using circles or rolls, atmospheric dust is collected from airflow and the stain-intensity measured photometrically. For gas detection, the paper is impregnated with a chromogenic reagent and color formation quantified by optical reflectance. 100 circles/box.