Though widely used as a blotting paper, 3MM Chr is used in both electrophoresis and for general chemistry. A medium thickness paper (0.34mm) used extensively for general chromatography and electrophoresis. Grammage (gsm): 185. Typical Thickness (µm) at 53 kPa: 335. Gurley (sec/100mL/sq.in): 20. Wet burst (ins H20): 12.