2810 



Chapter 23 



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BOARD THICKNESS 



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Figure 23-47. — Density profile of S2S hardboard. (Drawing after Spalt 1977.) 



PRESSING SIS HARDBOARD 



In the manufacture of SIS hardboad (fig. 23-48 top) mats move from wet- 

 press on the forming line to hot press with no intermediate drying stage (fig. 23- 

 28). 



Press lines. — Since pressing is a batch process, provision must be made in the 

 press line to match the continuous output of the wet press to the cyclic nature of 

 hot press operation. Coupling of line to press can be accomplished simply by 

 loading a number of mats into a series of movable press loaders which when full 

 are removed to one of a number of available hot presses. Each press loader holds 

 a number of mats equal to the number of openings per press. This is the 

 procedure of the Masonite Corporation in their Laurel, Miss, plant. 



Most other wet-process SIS hardboard plants have a direct coupling between 

 wet press on the forming line and hot press. The system provided by Siempel- 



