Exploring the multi-scale structure of printing paper--a review of modern technology

Printing paper is an important communication and information medium affecting our daily activities in several ways. The structure of paper may affect its optical, mechanical, fluid transport and print properties. In order to achieve a complete understanding of these processes a comprehensive characterization of relevant surface and bulk structures of paper is necessary. The paper grades considered in this study are newsprints, super calendered and coated papers. A detailed description of several image acquisition techniques used to assess the printing paper structures is given, including desktop scanners, profilometry, light microscopy, confocal laser scanning microscopy, scanning electron microscopy, atomic force microscopy, focused-ion-beam, X-ray microtomography and transmission electron microscopy. The presented methods cover a wide range of structure sizes, from the macro- to the sub-nano level. The complementary capabilities of the image acquisition techniques for assessing structural details of paper and prints are discussed.