1. Filter paper shall be a recent lot of S&S 903 or equivalent 100% pure cotton fiber, filter paper with no wet-strength additives or equivalent. Lot number to be printed on the filter paper attachment of page 3. 2. Basis weight should be 110 lb.+/- 5% per read (550 sheets 24 x 35 inches}. 3. Densitometer reading by Gurley method on one sheet with a 5 oz. Cylinder, 0.1 sq. orifice and 100 cc of air (Test method, modified ASTM D7266-58}. 4. pH should be 5.7 to 7.5 5. Ash% 0.2 maximum (Test method, modified ASTM D726-63} 6. Kelmn: Tappi modified useful method- UM451 7. Wet strength (ASTM D-774-67), usually around 4/5 lbs./inch sq. 8. Absorption rate: The absorption time and the diameter of blood spot produced by 100uL. Of a fresh whole blood sample (hematocrit 55 +/- 1%}. Absorption time target: 12 seconds; range 5-30 seconds. Diameter target: 16mm; range 15-17 mm volume. Ragged edges or mottling or dried blood spot should not be observed. 1/8-inch punch of dried blood spot should equate to a blood volume of 1.54+/- 0.17 uL. 9. Lithographic printing is not an acceptable printing process for the filter paper. A dedicated ink delivery system used only for filter paper printing is recommended.
