Ahlstrom manufactures a series of extremely high purity, acid washed filter papers designed for use in analytical and gravimetric analysis. The quantitative grades are manufactured from top quality cotton linters using ultra-pure, reverse-osmosis water and are further treated with dilute acid to remove any remaining organic and inorganic impurities. All quantitative grades are manufactured in a strictly controlled environment that ensures high uniformity and high purity from filter to filter. Quantitative analysis Low ash content 0.007% (Acid-wash treated) High wet-strength Consistent performance Custom cut Bulk packaging Ashless Grades (Ash 0.007%) These standard ashless grades are high purity filter papers suitable for routine quantitative gravimetric techniques and in the preparation of samples for use in analysis involving instrumental techniques. Ahlstrom 94: 1.5µm – Slow Speed This is an extremely fine retention filter for critical gravimetric analysis of very fine particles such as barium and lead sulfates, stannic and nickel sulfide, calcium oxalate and calcium fluoride.