〔報告〕鷹島海底遺跡出土の元寇関連漆製品に関する調査

In recent years, many urushi objects have been excavated at Takashima Underwater Site. These objects are thought to have been used in the Mongolian attack on Japan in 1281. Several analyses and observation using a microscope were conducted. As a result, some techniques different from traditional Japanese ones were found to have been used in making these objects. (1) Bone powder was found to have been mixed into the foundation. This is an ancient Chinese technique. (2) The thick black urushi layers of some bows contained many particles of red lead pigment (Pb3O4). (3) Elemental analysis by Py-GC/MS revealed that these black urushi layers were composed of urushiol. Moreover, much dry oil had been blended into the urushi. (4) It is known that mixing lead pigment into urushi reduces the fluidity of urushi which gains a certain creamy effect. This produces a certain amount of thickness in the urushi film but decreases the durability of the hardened film. (5) Although boiling is one way to harden dry oil like paulownia oil as a coating film, another method that has been traditionally used is to add lead pigment into dry oil. This is known as mitsuda technique. (6) It is possible that this technique was chosen because it was effective in mass producing weapons like bows and other expendable items

〔報告〕奈良文化財研究所における被災文書の保管、クリーニング作業場所の微生物環境調査

A large number of valuable cultural assets were seriously damaged by tsunami in the Great East Japan Earthquake on March 11, 2011. Since, in many cases, the seawaterdamaged documents were left wet and covered with dirty soil for several months, theywere subjected to significant mold damage as well. In order to salvage them, emergency treatments and their temporal storage were carried out all across the country. At the Nara National Research Institute for Cultural Properties, freeze-drying of a large amount of damaged documents was carried out, and the staff and volunteers were engaged in cleaning and storing severely molded documents for several months. Since working in such a condition posed a high risk of fungal exposure, the environmental contamination including that by airborne and material adhesive fungi in the storage and the cleaning workroom. Sampling of the damaged documents in the Institute was done on April 13, 2012. As a result of quantitative analysis of material adhesive fungi, a significant increase was detected in the working table, the air-circulating hood and around the groove of the windows as well as on the working clothes and mouth masks. Qualitative analysis showed that the dominant fungi were Penicillium spp., which were distributed throughout the indoor environment. On the other hand, dematiaceous fungi were often observed in some molded documents. The black fungi were identified as Stachybotrys spp.with microscopic morphological characteristics, but they failed to grow on appropriate media. The number of airborne fungi in the storage room and the cleaning workroom were higher than that in a normal residential environment. The dominant airborne fungi were also Penicillium spp., which were cultivated by the damaged documents. This investigation suggested that effective countermeasures are needed to prevent workers from fungal exposure during their work of cleaning and restoring molded documents

〔報文〕土質遺構露出展示保存のための基礎的研究―土中水のポテンシャル制御による遺構安定化の試み―

In this study, conservation method that prevents collapse of soil structural remains caused by drying and precipitation of salt by controlling the water potential gradient was examined. At Miyahata site located in Fukushima city, soil boring was performed to estimate the ground structure. In laboratory experiments, some parameters that determined water retention curve and hydraulic conductivity of unsaturated soil were estimated by evaporation method and inverse analysis with HYDRUS-1D. Based on the ground structure and unsaturated hydraulic properties obtained, water movement in vertical direction was simulated by numerical analysis. As a result of numerical analysis, it was revealed that the soil of remains would continue to dry. Then, the changes in water potential gradient caused by timely infiltration were also simulated. As a result, it was revealed that downward gradient of water potential and zero-flux plane could be produced alternately. By repeating infiltration and evaporation in a short span, it was revealed that deterioration of the remains caused by drying and precipitation of salt could be inhibited

〔報告〕水浸出土木製遺物の保存処理における溶媒蒸発を用いた薬剤含浸の効率化の可能性

In the conservation treatment of waterlogged wood, impregnation of a solute into wood for stabilization can be processed by immersing the whole wood in a chemical solution. However, since the penetration of solutes by diffusion is generally very slow, the efficiency of the process is severely limited. Though various types of chemicals have been proposed so far as impregnant for waterlogged wood in order to improve the efficiency of the impregnation process, the principle of impregnation itself has not changed significantly. In the pr esent study, the efficient method of impregnating chemical into waterlogged wood was examined based on the principle which was different from the conventional one. As a result of the preliminary experiment with PEG for impregnant, it is suggested that permeation and accumulation of solutes by advection can be efficiently progressed by immersing the waterlogged wood in the solution with the upperpart of it exposed to the air and controlling temperature and evaporation rate of the solvent. Also, the dimensional stability of the wooden sample after solidification of PEG was excellent. The experiment also suggested that there is the necessity of controlling the solvent evaporation rate properly so as not to exceed the rate at which the solution is absorbed into the wood. It is considered that the permeability of the solution inside wood is affected by the structure of wood, the degree of deterioration of wood and the viscosity of solution

〔報文〕高松塚古墳発掘／石室解体作業に伴う取合部・断熱覆屋使用木材等の防カビ対策：DDACの検討と施工

Takamatsuzuka Tumulus was excavated in 1972 and is known for its famous mural paintings on the plaster walls inside the stone chamber. However, after the tumulus experienced several outbreaks and damage by microorganisms, difficulty has been recognized in keeping the paintings in high humidity. Relocation of the mural stones and an archaeological excavation were performed in parallel in 2007. During the project, a tentative building was constructed in order to keep the relative humidity of the environment surrounding the stone chamber at about 90% to prevent exfoliation of the mural paintings. At the same time, the temperature was kept at about 10℃ in order to slow down the growth of molds on the mural paintings. But this high humidity was likely to encourage mold growth in the tentative building and an adjacent area in front of the stone chamber. So treatments with biocide, DDAC (1-Decanaminium, N-decyl- N, N-dimethyl-, chloride ), to wooden panels, timbers, sand bags and so on, which would be used in the front space and the tentative building, were performed. The selection of the chemical was based on: (1) relative low toxicity to humans (2) little odor and little emission of toxic volatile chemicals from treated materials, and (3) expectation of the duration of the effects for at least several months. Small tests on the effects of DDAC were performed. Wooden blocks, sugi (Cryptomeria japonica) and hinoki (Chamaecyparis obtusa), treated with/ without DDAC were placed in a glass jar of approximately 100% relative humidity at room temperature. After two weeks, mold growth was observed on an untreated block of sugi, but was not on a control block. After three months, there was no obvious signs of mold growth on DDAC-treated wooden blocks. Approximately 5% of the DDAC solution was applied to the materials by brush painting or spraying; then they were dried. The DDAC-treated materials were placed under high humid conditions of the Takamatsuzuka site for about three to several months during the excavation and relocation of the stone chamber in 2007. During these periods, no obvious mold growth was observed, which suggests successful treatment by this method

〔報告〕Ｘ線透過撮影による泥に覆われたキトラ古墳壁画の調査

Among the twelve zodiac signs in the wall paintings of Kitora Tumulus, the signs of dragon, snake and monkey have not been discovered because they are covered with mud. In order to decide the treatments for restoration, it is important to identify the existence of those signs. Therefore, the authors conducted investigation by X-ray radiography.In order to conduct the investigation of the wall paintings safely and efficiently, the conditions for X-ray radiography, for example the tube voltage, were determined in advance by checking the X-ray images of a test piece which reproduces the structure of the wall paintings.As a result of the investigation by X-ray radiography, signs of snake and monkey could not be recognized in X-ray images. On the other hand, an image appeared at the location where the dragon was expected to be drawn. However, the obtained contrast of the X-ray image was opposite to expectation; the transmittance of X-ray around the image looked lower than that on the image. One of the possible reasons is the recrystallization of calcite on the surface of the plaster where no image was drawn

〔報文〕桃山文化期における輸入漆塗料の流通と使用に関する調査

In recent years, ｍany four-lobed jars were excavated at the center of Kyoto city (O-ike site). These jars were imported from Thailand or Cambodia from the end of the 16th century to the first half of the 17th century. Some jars were stocked with black urushi sap paints. Results of elemental analysis by GC/MS specific heat showed that these black urushi paints were composed of Melanorrhoea usitata (grown in Thailand, Cambodia, and Myanmar), not Rhus vernicifera (grown in Japan or China) or Rhus succedanla (grown in Vietnam). According to old documents, a large amount of urushi paints was used on objects and wooden buildings during the Momoyama cultural period. But in those days the production of raw urushi paints made in Japan was not necessarily sufficient. So many raw urushi paints were imported from Southeast Asia. Thus, black urushi paints stocked in these excavated jars were actual materials imported from Southeast Asia during the Momoyama cultural period and used in Kyoto

キトラ古墳保護覆屋内の環境について―温度・湿度と炭酸ガス濃度―

Kitora Tumulus is located in Asuka-mura, Nara prefecture and is thought to have been founded in the late 7th century. It is famous for its decoration with paintings of Chinese god beasts and animal servants on the walls of its stone chamber. Excavation started in 2004 and the relocation of paintings are now being executed. In this article, the environmental conditions in the conservation work of 2004-2005 are reported. Methods for controlling the environment of the buffer zone next to the stone chamber are also documented. It was made clear that sensors to measure humidity and carbon dioxide concentration did not have long life under especially high humid conditions of approximately 100% RH. However, it was found that a carbon dioxide sensor might detect the threat of explosive growth of microorganisms at an early stage

〔報告〕デジタル画像撮影による高松塚古墳壁画表面状態の調査

Since the discovery of full-colored murals in the stone chamber in 1972, the Takamatsuzuka Tumulus had been conserved on-site. However, in recent years, staining by molds and blurring of the murals have become serious issues. The Agency for Cultural Affairs (Bunkacho) decided, in 2005, to dismantle and move the stone chamber to a newly constructed facility for restoration. Restoration and various scientific investigations on the murals have been conducted since 2007. The purpose of this research is to acquire detailed visual information on the present surface condition of the murals by digital photography. A compact digital camera (Ricoh GX-100, about 8 million pixels) was attached to a specially designed frame, which surrounded the dismantled stone, to be facing the mural. This camera can take images of an area approx. 3.0 cm x 4.5 cm with the working distance of about 8.5 cm. Images were taken with slanting rays of white LED light illumination from the right. As a result, it was found that two different phenomena, besides molds, were concerned to the blurring of murals:　　i )　vanishing of painting materials from plaster　　ii)　appearance of milky-white solid substances on the plaster and painting materials. Milky-white substances in various forms such as paste, particle and sphere, were found distributed widely on all murals. These substances are assumed to be calcite, which eluted from the plaster by some reason. Identification and investigation on the cause of generation of these substances are to be considered in the future