A paper with low filtration speed and high wet strength. Its chemical resistance corresponds to Grade 1573 hese extremely strong filter papers have a high wet strength due to the addition of a small quantity of chemically stable resin. Normal qualitative applications will not introduce any significant impurities into the filtrate. The resins do, however, contain nitrogen so these grades should not be used in Kjeldahl estimations, etc. Some wet strengthened grades are available in folded (prepleated) forms. Slow filter paper with high wet strength. Grade 1575: <2µm 2 µm