Chemistry of pulp and paper making . e in Mullen Test trates four typical ruptures and in which the arrows indicate themachine direction. Wire or Felt Side. In many cases this may be determinedvery easily by a simple inspection but in some papers the wiremarks do not stand out at all plainly. Sometimes they may bemade more prominent by plunging the sample for a momentinto water and draining or blotting off the excess. The moist-ure causes the fibres to expand, thus undoing the work of thecalenders and restoring the texture of the sheet as it left themachine wire. Inspection of a sheet thus dam
Chemistry of pulp and paper making . e in Mullen Test trates four typical ruptures and in which the arrows indicate themachine direction. Wire or Felt Side. In many cases this may be determinedvery easily by a simple inspection but in some papers the wiremarks do not stand out at all plainly. Sometimes they may bemade more prominent by plunging the sample for a momentinto water and draining or blotting off the excess. The moist-ure causes the fibres to expand, thus undoing the work of thecalenders and restoring the texture of the sheet as it left themachine wire. Inspection of a sheet thus dampened will often WEIGHT OF SAMPLE 397 show that the wire marks stand out plainly, where before theywere indistinguishable. This method very often proves satis-factory even for coated papers. Weight of Sample. The weight of a sample of paper is usu-ally expressed as so many pounds per ream of a given size, butthe number of sheets per ream and the standard size of the sheetare more or less variable in the different branches of the in-. FiG. 44. Beam Type of Paper Scale dustry. Where a full sheet of paper is available the weightper ream may be conveniently found on scales of the typeshown in Fig. 44. The folded sheet is placed on the hooksand the weight per ream is shown by the position of the shdingpoise on the beam. This instrument, which is largely used formill work, is usually graduated for reams of both 480 and 500sheets. Two representative scales of the quadrant t}^pe are shown inFig. 45 and Fig. 46. With these the weight per ream in pounds
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Keywords: ., bookcentury1900, bookdecade1920, bookpublishernewyo, bookyear1920
