2.3. Paper sheet preparation
The laboratory paper was made by a semi-automatic sheet machine (British Handsheet Machine) according to
TAPPI T 205 om-88 Forming Handsheets for Physical Tests of Pulp. 24 g of free moisture content pulp required to
produce overall test sample according to 60 gsm paper. Firstly, pulps were disintegrated to disperse the bundled
pulp. 2 liters of water were added into the disintegrator tank contain with the pulp and run for 2000 revolutions.
After completion, the disintegrated pulps were poured into the stock divider. Water level inside the stock divider
was raised up to 8 liters level. Pneumatics air bubble used to mix the pulp and water evenly.
The freeness test was conducted according the TAPPI T 227 om-99: Freeness of Pulp (Canadian Standard
Method). 2 sets of freeness diluted pulp (1 liter of diluted pulp per set) were taken out from the stock divider to
perform the freeness test by a freeness test apparatus. After completion, the same 2 sets of freeness pulp were used
to produce paper sheets by a sheet former. The two pieces of freeness paper sheet were dried in the oven at 105°C to
determine the freeness correction value. After the 2 sets of freeness sample were taken out from the stock divider,
the water then was added again until it reached 14 liters level.
2 sets of correction sample (1 liter of diluted pulp per set) were taken out from the stock divider. Correction test
must be performed to check the weight of the paper sheet is over or lower than as standard weight. 2 pieces of
correction paper sheet were produced by paper sheet forming process. The paper sheet then dried using the rapid flat
dryer at 105°C. For 60 gsm paper, the standard weight was 1.22 g. Water was reduced from the stock divider if the
weight of the correction paper is lower than the standard. Besides, water is added if the weight of paper is over than
the standard. Air bubble in the stock divider must be closed and pulp must be left for about 20 minutes if the water
needs to be reduced.
The remaining 12 liters of diluted pulp inside the stock divider used to produce the testing samples after the
correction procedure has been done. Hand sheet former is an apparatus to produce a paper sheet consists of a
complete sheet machine, perforated stirrer, couch roll, couch plate and a grid plate as shown in Fig. 5(a). From the
stock divider that contains of 12 liters diluted pulp, it can produce into approximately 12-13 pieces of testing
samples. Sheet making procedure was started by turn on the water while the sheet machine was open to remove any
adhering fibers. 1 liter of diluted durian rinds pulp was poured into the sheet machine cylindrical deckle after the
sheet machine was closed and filled with half of water. Water was added until it reached the line level inside the
sheet machine. The perforated stirrer was inserted into the sheet machine and moved upward and downward for
about 5 times to uniformly mix the slurry. The drainage time is taken by a stopwatch when the water outlet valve is
release rapidly. After the water drained out under suction by opening the water valve rapidly, only a drained sheet
was left on the wire screen as shown in Fig. 5(b). The drainage time is stopped after water is fully drained. 2 pieces
of blotter paper were placed on the centre of the paper sheet and a couch plate is placed centrally on the blotter
papers. The couch roller is rolled forwards and backwards on the centre of the plate without any pressure for 3-5
times to remove residual water contain and make the paper sheet attached on the couch blotter paper as Fig. 5(c).
After completion, all paper sheet samples must be pressed uniformly with press machine in order to make sure the
sample in a flat shape and also removes the residual water content. Each paper sheet sample attached to the couch
blotter were placed on the 2-3 pieces of dry blotter and covered by a polished plate on the top of it located to the
centre of the press machine flat base by using a guide as shown in Fig. 5(d). The samples were pressed
approximately at 345 kPa of pressure for about 5 minutes. After changing the blotter paper between paper sheets, the
pressing procedure was repeated for another session with same pressure and time.