Volume 44, Issue 4

The current study conducted in March–April 2021 elucidated the acidification process of books using alkaline text paper and improved the method of pH measurement in a previous study from 2016. The pH was measured on various positions of Japanese books published in 2000–2020 using the same type of pH-indicator strip as used in 2016; however, a wetted pH-indicator strip was kept pressed to the text paper with fingers at approximately 5 kgf for 90 s to secure the transfer of water-extracted components for four times while a 250 g paperweight was mounted and kept for 60 s for two times in the 2016-study. This time, the pH was found to decrease faster in positions more readily exposed to outside air compared to the 2016-study. Immediately after publication of the book, the pH was approximately 7.8 in every position. The pH of the top edge corner and the surface near the top edge corner later decreased to a neutral pH 7.0 4–6 years and 7–9 years after publication, respectively. Approximately 20 years after publication, the centre of the page in the interior of the book also dropped to pH 7.1, suggesting that acidification steadily progressed, albeit slightly, even on alkaline paper.

The properties of handmade paper used for mounting and conservation of paintings and calligraphy on paper is crucial to the quality and lifespan of such objects. Mounting papers from China, Korea, and Japan vary greatly in performance due to different papermaking methods and fibre materials. In this study, eight types of handmade paper widely used in China, Korea, and Japan were selected for comprehensive comparative analysis investigating their pH as well as optical, mechanical, and ageing properties. The study showed that traditional hanji, improved hanji, and thin Mino paper made of pure kozo fibres performed best in terms of mechanical properties. Among the additives mixed with kozo fibres, clam shell powder was identified as a substance that improves pH and stability of optical properties. Xuan paper Mianliao was found to be a suitable material for mounting hand scrolls and hanging scrolls due to its softness and ageing properties. Traditional hanji, improved hanji, and thin Mino paper are less flexible than xuan paper Mianliao and are considered more suitable for uses other than for mounting scrolls. This study will provide a reference for improving the quality of handmade paper and a theoretical basis for the selection of such papers for the conservation of paintings and calligraphy on paper.

Throughout history, bookbinding incorporated advancements in techniques, usage of a wide range of materials, and application of imaginative designs. Lacquered bindings are just one of several technical breakthroughs attributed to Persian artisans. They consist of a sophisticated structure of numerous layers. This study explores each layer and their materials and methods, including motifs used from the Safavid to Qajar periods. Moreover, various treatments used for each layer during manufacture as well as various methods for preparing paper pasteboards, including marqaš , ṭalāyi, tah ṭalāyi, zarak, dūdī, and abrī have been investigated through literature research and reconstruction. The intricate layer combinations used in Persian lacquered bindings cause several simultaneous chemical processes. Chemical, physical, and biological degradation are significantly influenced by raw materials and the original manufacturing process. Separation of layers, softening, yellowing and loss of transparency, cracking, hazing, and pigment as well as metal corrosion brought on by internal and external deterioration factors including light, temperature, and relative humidity will also be covered in this study.

Manuscripts are one of the most important cultural heritage objects that not only contain essential information, but also provide valuable insights into the social, cultural, and economic conditions of the era in which they were written. These materials are subject to degradation over time due to both internal and external factors. While ageing processes of pure cellulose or the effect of iron gall ink on cellulose have been studied extensively, there is little known about deterioration mechanisms in dyed paper. In this study, safflower ( Carthamus tinctorius L.), buckthorn ( Rhamnus petiolaris Boiss), turmeric ( Curcuma longa L.), and onion peel ( Allium cepa L.) plants as well as cochineal insect ( Dactylopius coccus Costa) extracts were used to dye Whatman filter papers. Samples were then subjected to accelerated ageing to determine the long-term effects of the dyes. Colour, pH, viscosity, and glycosidic bond breakage rates were measured before and after ageing. Onion peel dyed paper exhibited the highest rates of degradation, followed by buckthorn, cochineal, safflower, and turmeric-dyed paper. The alum and tannin content may have caused the degradation. The findings of this work may provide conservators with valuable scientific data on the effect of dyes on the degradation kinetics of cellulose.