. The manufacture of pulp and paper : a textbook of modern pulp and paper mill practice. ineor a more powerful suction, but will give a better formed sheet,due to the filling in by the fibers. 56. Freeness Tester.—A familiar form of freeness tester isshown in Fig. 19. It is made in two main parts: a container A for holding the stock while drainagetakes place through the fiber mat andwire bottom B on which the matforms; the funnel C into which thewater passes after being strainedthrough the fiber mat. The funnelhas two outlets; one D, at the bot-tom is | inch in diameter, while theother E, on t
. The manufacture of pulp and paper : a textbook of modern pulp and paper mill practice. ineor a more powerful suction, but will give a better formed sheet,due to the filling in by the fibers. 56. Freeness Tester.—A familiar form of freeness tester isshown in Fig. 19. It is made in two main parts: a container A for holding the stock while drainagetakes place through the fiber mat andwire bottom B on which the matforms; the funnel C into which thewater passes after being strainedthrough the fiber mat. The funnelhas two outlets; one D, at the bot-tom is | inch in diameter, while theother E, on the side, is \ inch insidediameter. Since the hole in thebottom is not large enough to passa large volume of water under a lowhead, there is an overflow through theside hole E, and a graduated cylinderF is used to catch this volume of water passing throughthe overflow is a measure of the free-ness of the stock, a free stock causinga large overflow and a slow stockcausing a smaller overflow. Thistester is also adapted to pulp-millcontrol. (See Section on MechanicalPulp.). Fig. 19. 67. Operation of Freeness Tester.—About 500 grams ofmechanical (groundwood) pulp stock from the deckers or thicken-ers (equivalent to about 20-25 grams, bone dry) is placed betweenlayers of felt, inserted in a wine press or a letter press, and ispressed firmly, but not too hard. If pressed too hard, time andaccuracy are lost in breaking up the pulp, for making the pulp should contain about 50% of moisture. The pressedcake of pulp is rubbed between the hands and mixed thoroughly;20 grams are weighed on a scale that is sufficiently accurate toweigh to gram, and is then dried to determine the bone-dryweight, from which the per cent of bone-dry pulp can be remainder of the pulp is placed in a corked sample bottle. §8 TESTING OF PULP 35 The per cent of bone-dry weight is calculated to one decimal found this, weigh out the amount of pressed pulp thatwill c
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