Preservation Status And Disease Research In Cave 245 Of Mogao Grottoes

Mogao grottoes is a temple site,it is biggest in scale,rich in contents,diversity on themes,exquisite on art,preserve integrity,the most influential,contained the wall paintings,sculptures and architectures in together.It is the significant joining of Chinese civilization connects with ancient Greek,ancient India,Islamic civilization and other eastern and western cultures.Mogao grottoes is famous for "the museum on the wall",it was listed into the world cultural heritage list by UNESCO on 1987.Mogao grottoes is Chinese art treasure,the splendid temple of god of Buddhist grotto art,the art of painting is the only witness of the three dynasties of Sui,Tang and Song of China.Cave 245 located the second floor of the middle of southern district,built on Uighur ruling time.It is the representative cave of that time,the special patterns of Uighur style are appeared on the wall painting,such as:the woven pattern flammule,the three beads flame,gyrose cloud pattern,reel straw pattern and etc.,and the portraits of the unique Uighur men and women donors.They provide the historical researching materials on Uighur,religion art,traditional Chinese paintings technique and materials,and Buddhist art development.The architectural decorative patterns and the costume provide the historical,artist and scientific values.This paper according to the wall paintings materials and technique,analyzing the salts of plaster,connected with the conservation condition of wall paintings and the cliff consolidation condition,discussing the cause of the disease at north-eastern corner of C245,designed the simulated experiment.Through the experiment phenomenon and the result to verify the cause of the disease,and providing the monitoring method.The main points as follows:1)C245 has double wall paintings,every wall painting followed the traditional technique:support,coarse clay,fine clay,ground and color.The thick of the wall painting of the surface layer is 0.5-1 cm,contains the fine clay with hemp and the coarse clay with wheat straw,the thick of the fine clay is 0.2cm.The fibre content is 2.5%of the surface plaster.The mineral pigments were used.The thick of the ground is 50-150?m,the thick of the color is 10-50?m,it is thinner.The plaster is formed by clay grain,the diameter mode of the grain is 0.6?m or so,similar with the Dengbantu,a kind of local clay grain(1.6?m)of Dunhuang.According to the materials of the surface wall painting,such as:mineral pigments,the phase of the clay of plaster,the diameter of grain;and the thick of the color,fine clay and cross-section structure,shows that,the materials and technique of the surface wall painting are similar.2)The data of the consolidation of cliff shows that,the anti-chamber of C245 was in hanging condition before 1914,since the collapse of cliff and all kinds of cracks.After the second engineering reinforcement of 1965,except the disruption and detachment area on the up of north side of the eastern wall,there were fallen paintings in 50 years,all the others are steady.3)The analyzing of ion chromatography from sample of the plaster of C245 shows that,the salts content is more than 1%,it is higher.The anions of soluble salt mainly Cl-and SO 2-4,a small number of NO3-.Positive ions are mainly Na+,a small number of Ca2+ and K+.The salts content of disraption and detachment area of the eastern wall is 40%.Comparing with other salts content of plaster and the historical record of Mogao,the salts of the disruption and detachment area of the eastern wall come from somewhere other place,through dissolution,migration and crystal,then,causing the disease.4)Through analyzing the materials and technique,salts content of the plaster,conservation condition and disease cause,we can estimate that the cause of the disease of north-eastern corner is water seepage by cracks.So,to verify the reasonability and the simulated experiment was designed.During the experiment,every samples group occurred different damage and disease,such as:cracks,cock,fall off of the color;crater eruption,disruption,salts shell,salts efflorescence and etc.,anyway,the estimate is verified.5)Providing several monitoring methods:using the dividing rule and the vibration wire surface crack meter to monitor the cut-through cracks;using the contact humiture recorder and infrared imager to monitor the moisture;using the fixed point film and three point relocation to monitor the color changing of salts shell.This research through the wall painting materials,technique and salt content,connected with all kinds of cracks of cliff,the simulated experiment,according to the experiment phenomenon and result to verify the cause,then providing the monitoring methods.The research has the important guiding significance for other similar wall paintings preventive conservation and monitoring,and it is the theoretical foundation.