Pulp and Paper 



3111 



TENSILE 



BEATING 



TIME 



— ► 



Figure 25-15. — Typical relationships between pulp beating time and three strength 

 properties of paper. (Drawing after Whitney 1980.) 



an endless, moving, horizontal wire screen. After drainage on the moving screen 

 the partially dewatered sheet is passed through continuous drying processes. 

 This Fourdrinier machine has not changed in principle since its invention in 

 1799, but evolutionary developments have been significant. Machine widths 

 have been increased from about 3 feet to about 30 feet, and speeds from a few 

 feet per minute to 3,000 feet per minute. Most paper machines have a single wire 

 screen, but some have two screens so that the sheet being formed is always 

 contained between the moving wires and never encounters an air-slurry interface 

 (Whitney 1980). 



Readers interested in further study of the technology of forming paper sheets 

 from hardwood pulps should find the following references useful: 



