3094 Chapter 25 



WOOD PULP, MECHANICAL FOR "OTHER" PAPER AND BOARD 



These coarse, often brown, pulps are used in the manufacture of insulating 

 board, construction paper, and wet-machine board. 



Stone groundwood and refiner pulps are produced by stone groundwood or 

 refiner processes. 



Defibrated/exploded pulps are produced by explosion process (see sections 

 18-27 and 23-6), and by pressurized refining to yield an economical, coarse 

 brown pulp suitable only for "other" paper and board 



Screenings are rejects and off-quality screenings from all grades of wood 

 pulp, except dissolving pulp. 



WOOD PULP, CHEMICAL 



Semichemical pulps are high-yield pulps produced with some chemical agent 

 such as neutral sulfite, or alkaline liquor followed by mechanical refining. 



Sulfate and soda paper grades of pulp are produced by the sulfate (kraft) or 

 soda process. Bleached pulp must achieve a G.E. Brightness of more than 75. 

 Semi-bleached pulp must achieve a brightness of not less than 45 or more than 

 75. 



Sulfite paper grades of pulp are produced by the sulfite process. Bleached 

 pulp must achieve a G.E. Brightness of more than 75. 



Dissolving and special alpha pulps are highly refined bleached white and 

 sulfite or sulfate pulps with a high content of alpha (pure cellulose) fiber. 



CONSTRUCTION PAPER AND BOARD AND "OTHER" 



Construction paper includes sheathing paper, felts (for roofing, floor cover- 

 ing, automotive use, sound deadening, pipe covering, and use in refrigerators), 

 asbestos paper and asbestos-filled paper, and flexible wood fiber insulation. 



Insulating board is a fibrous-felted homogeneous panel made by inter- felting 

 of fibers, e.g., interior building board, wallboard, sound-deadening board, 

 acoustical tile, exterior sheathing board, roof insulation board, and trailer board. 



Wet machine board includes binder's board, shoe board (e.g., counter 

 board, heel board, and innersole), automotive board, chair seat backing, coaster 

 board, luggage board, panel board, table-top board, mill board, and others of 

 similar type. 



