The Characterization of Selected Mechanical and Optical Properties of Low-Density Japanese Papers

Tensile testing has been a commonly used method forassessing the mechanical characteristics of paper for many years. In this study, seven types of low density, machine-made Japanese washi-papers were selected and used for a comprehensive comparative analysis investigating their properties. These low-density papers have not yet been studied intensively. The mechanical properties of each paper sample have been compared according to three different testing devices, and the morphology of fibers was analyzed employing optical microscopy. In this study, three different and unique instruments were used for performing the tensile strength measurements. Characteristics such as: lightness, color, grammage, thickness, and tensile strength for each paper sample were statistically analyzed to determine the generalized features of the papers. Consequently, this study contributes to a better understanding of the inherent mechanical properties of low-density Japanese papers, as well as simultaneously improving on the existing knowledge of machine-made papers made from inner layer of bast fibers. In connection with the obtained results, the specific use of Japanese washi-papers in the field of conservation and restoration technologies can be recommended. Understanding the characteristic mechanical and optical properties of low-density machine-made Japanese washi papers enables more informed material selection in conservation and restoration practice, including the potential use of papers with lower density than traditionally employed, thereby ensuring adequate mechanical support while achieving improved visual integration and preservation of the historical authenticity of treated objects.