Evaluation of the changes in paper structure by the laboratory wet pressing conditions

The effects of the laboratory wet pressing conditions on the structural parameters of paper were investigated systematically. Especially, the local variation of apparent density was evaluated by applying the twin laser profilometer (TLP) and the storage phosphor β-radiographic imaging system. The results showed that the densification by wet pressing was distributed across the entire sample area. The relationship between the wet pressing densification and the dryness (water removal by the wet pressing) was found to be different depending on the felt fabric, which indicated the higher dryness without increased densification could be possible by choosing proper fabric condition. The effects of the fabric type on the surface structure were also investigated.