Whatman offers an extensive line of filter papers. The innovative features of these filters make them the optimum choice for many filtering techniques. Whatman maintains a guaranteed quality, reproducibility, and uniformity for all its filters by using only the highest-quality raw materials. The filters are tested for basic weight, thickness, air flow, and mechanical strength. in addition, special parameters such as particle retention, wicking rate, filtration performance, and surface characteristics can be measured as needed.