Ahlstrom offers a full range of specially designed filter paper for use in the sugar industry. Grade 8613 has a smooth black finish designed for use in applications requiring visual examination of particles. Grade 613 and 615 are particularly well suited for general laboratory filtration methods and qualitative analysis. Qualitative analysis, low ash content 0.06 percent, untreated, consistent performance, wet-strengthened grades, custom designed for end-use application, custom cut.