RAW MATERIALS PAPER 237 



Next, the beaten pulp, when properly mixed, is 

 sized and loaded with some filling substance, such 

 as china clay, and, after various rectifications to clean 

 it or to remove local knots of stuff, the pulp is de- 

 livered in a thin liquid sheet on to the paper-making 

 machine the wire-wove travelling belt. 



Here, as the water drains away, the fibres of the 

 pulp take up their final positions and felt together. 

 The act of felting is promoted by shaking mechanisms 

 which overcome a tendency which the fibres possess 

 to lie parallel to the direction of flow. 



Next the sheet is dried, partly by gravitation, partly 

 by suction from below, and partly by heated rollers, 

 the rate of travel of the web being adjusted to the 

 rate at which the water is given up. 



Further operations to which it is subjected include 

 water-marking, sizing, the removal of superfluous 

 size, the smoothing of the surface, and calendering. 

 Finally the paper is cut into the desired widths and 

 lengths, counted, and packed. 



Now the chemical and physical qualities of the 

 paper are related in the most intimate way to the 

 original properties of the fibre, modified by these 

 various operations. 



Esparto has a fine fibre of circular section and 

 small central cavity. It resists excessive hydration, 

 and quickly parts with its water on the machine. Its 

 fineness and consequent flexibility confers on the pulp 

 admirable felting qualities for binding the sheet to- 

 gether with a uniform texture. As the fibres do not 



c> 



rest too closely over one another, but stand up, esparto 

 gives " body " to a paper. 



Wood pulp, having fibres flat in section, which lie 

 close over one another, gives a non-porous paper of 

 more continuous texture. As the fibres undergo hy- 

 dration, becoming gelatinous, they become firmly 



