8.3 Filtering
8.3.1 A black filter paper is placed on a glass-fritted funnel. Pour the contents into the 250 mL beaker and apply slight vacuum. The contents in the beaker may be divided into two or more portions in order to prevent overlapping of stickies in the case of high stickies and debris concentration. When a pressure screen reject sample collected from a recycling plant is tested, flakes should be picked out before filtering to avoid covering of stickies. 8.3.2 When automated filtration device is used, place a black filter paper on filtering plate before screening. 8.4 Heat-setting 8.4.1 After filtering, a coated paper described in 6.4 is placed on top of the moist black filter paper and then sandwiched between two blotters. The sandwich is placed between the lower and upper heated plates of a press. The sandwich is pressed at 0.8 bar (11.6 psi) for 10 minutes at 90C (194F). 8.5 Filter washing 8.5.1 After heat-setting the stickies, the coated paper is removed from the black filter paper. Flakes, shives, grit, and other non-tacky contaminants are washed off under controlled conditions with a flat spray nozzle for 20 - 25 s. The water pressure is about 1 bar (14.5 psi) at a flow rate of 9.6 1/min (2.6 gal/min). Distance between the spray nozzle and the filter paper is approximately 180 mm (7 in.). 8.6 Post drying 8.6.1 The washed black filter paper is covered with a silicon paper and is dried in the automated press for 5 min. Temperature and pressure are the same as in 8.4 8.7 Marking 8.7.1 The white coating pigments are now identifying the stickies on the black filter paper. If any light colored fibers or other light colored non-tacky contaminants remain on the black filter, a black felt pen is used to dye them black. 8.8 Image analysis 8.8.1 Follow the manufacturer’s instructions to use an image analyzer. 8.8.2 The image analysis system is programmed to start counting at 100 microns (0.0078 mm2) in diameter using an inverted video mode. The black filter is backed with a black cardboard to prevent any readings from the cover if a scanner-based system is used