The article describes a historic Japanese green pigment which was identified in a painting attributed to the Kano school, dating to the Edo period. According to literature, malachite–which is the common translation of the Japanese term rokushō–has been the most widely used green pigment in Japan over a long period of time. Its colour shade could be modified by the use of different degrees of grinding and by heating the pigment. The green paint layer found in the painting was examined using XRF, SEM-EDS and XRPD, and cross sections. Examinations revealed a heterogeneous paint layer which consists of a mixture of various natural copper-containing minerals, some of which also contain arsenic and other elements. A concluding discussion of pigment nomenclature in Japan raises the question if rokushō may in fact be equated with pure malachite.
The aim of this research was an investigation into creating a rigid gel application of benzotriazole (BTA), a complexing agent, as a new potential way of treating verdigris-damaged paper. Various gel recipes were mixed and tested on historical samples. The gel recipes varied in gellan gel concentration, BTA/solvent solution concentration, and BTA concentration. The recipe effectiveness was assessed using Hulthe’s indicator paper and MQuant™ Test Cu indicator strips, two types of indicator papers which detect free copper ions. The results showed that rigid gel application of BTA is effective in complexing the copper ions which may inhibit further damage to the paper caused by free copper ions. Some of the other effects of the gel were the simultaneous removal of paper discolouration by the gel. Further research is needed to refine the gel recipes as well as the treatment process to prevent or reduce potential tidelines and other possible negative side-effects of gel treatment.
Three copies of a book that had been optionally deacidified using two different procedures in 1967, and then subjected to accelerated aging, were tested again after 52 years of natural aging. Matched copies of the book Cooking the Greek Way, which had been printed in Czechoslovakia on acidic paper, were evaluated. Nonaqueous treatment of two of the copies with magnesium methoxide dissolved in chlorofluorocarbon solvent had been found in 1967 to have decreased the susceptibility to embrittlement, as evidenced by the results of the accelerated aging, followed by folding endurance tests. Retesting of the same books in 2019, after 52 years of room temperature storage, showed that the deacidification treatments had achieved the following benefits in comparison to the untreated book: (a) higher brightness; (b) higher folding endurance; (c) tensile breaking length higher in the cross-direction of the paper; (d) substantial alkaline reserve content, (e) an alkaline surface pH in the range 7.1–7.4, and (f) higher molecular mass of the cellulose. Remarkably, some of the folding endurance results matched those of unaged samples evaluated in 1967. Scanning electron micrographs showed no differences between the treated and untreated books.
Ola leaf manuscripts from Sri Lanka date back to several centuries. While they have been well preserved over the last century, their condition has worsened in recent years when black dots caused by microorganisms started occurring on their surface. In this study, the current state of preservation and the factors causing deterioration are examined using microscopy techniques. Microscopic images clearly show that the manuscripts are contaminated by microorganisms which penetrated deeply into the carrier material, destroying the internal structure. A Penicillium griseofulvum strain was recognized as the most active microorganism in xylan degradation. Sri Lanka’s climate provides favorable conditions for the growth of these fungi. Therefore, it is suggested that temperature and humidity of the archival space should be better controlled in order to ensure the Ola leaf manuscripts’ long-term preservation.