These ashless papers are manufactured with 100% cotton linters. They are being washed with acid and cleaned with demineralised water to maintain its purity for quantitative analysis.
Grade 12: Medium fast filtration for very coarse precipitates such as lead, iron, silver sulphide, alcali carbonates, lead chromate, arsenic, antimony, cadmium and food stuffs.
Grade 14: Slowly filtering narrow pores filter paper used in fine precipitates such as lead dioxide, calcium fluoride, nickel sulphide, zinc sulphide, dioxide and molybdate of lead.
Grade 15: Very slowly filtering fine pores filter paper used for extremely difficult filtration conditions such as cold barium sulphate, metastannic acid and cuprous oxide.