| The Palace Museum is the imperial palace of Ming and Qing Dynasties,also known as the Forbidden City.It is the essence of ancient Chinese palace architectures.It is one of the largest and most complete wooden structures in the world.Qianlong Garden is located in the west of Ningshou Palace on the East Road outside the Forbidden City.The color paintings have very important historical value,artistic and scientific value.In this paper,the Qianlong Garden-Xiefang Pavilion,Songxiu Pavilion and Sanyou hall are selected for analysis,restoration and protection.They represent the characteristics of color paintings in Qianlong,Guangxu period and the Republic of China period respectively.Long-term affected by the outdoor natural environment,the color painting appeared a large area of disease.Therefore,it is urgent to repair and protect the architectural color paintings,The following six tasks have been carried out:(1)Through consulting materials,literatures and books,this paper introduces the production materials of color painting,the analysis methods of pigment and cement at domestic and foreign studies in recent years,and the common restoration and protection materials of color painting.(2)Based on the preliminary investigation of the color paintings of three buildings in Qianlong garden of the Forbidden City-Xiefang Pavilion,Sanyou hall,Songxiu Pavilion,it is found that the main diseases are cracking,warping,pigment powdering and surface dust.The results show that the annual relative humidity great changes,the high light intensity from July to August,and many kinds of air pollutants.In addition,it further analyzes the influence of various factors on the disease of color painting.(3)This paper studies the raw materials and technology of color paintings of three buildings in Qianlong garden of the Forbidden City.PLM,EDX,Raman,XRD,GC/MS and Py-GC/MS were used to analyze the morphology and composition of pigments,cements and fibers in three architectural color paintings.Xiefang Pavilion use the Yi Ma Wu Hui layer technology and the color paintings on the inner eaves of Xiefang Pavilion are made of vermilion,minium,Prussian blue,atacamite,cerussite and carbon black.The cement of pigment layer is animal glue.Flour,tung oil,ramie fiber and inorganic filler brick ash are detected in the mortar.Sanyou hall's color paintings use the Dan Pi Hui technology,mainly including emerald green,carbon black,ultramarine,cinnabar,anglesite,hematite,azurite and other pigments,the pigment layer cement is also animal glue,the mortar cement is flour and tung oil,and the filler is brick ash.In the painting of Songxiu Pavilion,which mainly uses minium,ultramarine,emerald green,lead white,carbon black and other pigments.The pigment layer cement is the same as the animal glue used in the other two architectural color paintings.The cement in the mortar is mainly tung oil and epoxy resin.The fiber used in Songxiu Pavilion painting is ramie fiber.(4)The modified graphene(m-GO)was combined with FEVE resin,which was used as the protective and reattached material of color painting(FEVE/m-GO).Because of the excellent physical and chemical properties of m-GO,when the content of m-GO is 0.04%,the contact angle,water absorption,shear strength and light shielding performance are significantly improved compared with FEVE and B72.When FEVE/m-GO was applied to the simulated samples,it was found that FEVE/m-GO had less water absorption,good salt resistance and UV resistance,and acceptable color difference.(5)In this work,we mainly modified bone glue from two aspects to optimize its freezing point and water resistance,and used it as a reinforcement material for color painting powdering disease.Firstly,the best process ratio of modified bone glue was selected by single factor experiment and response surface optimization method,and then the films properties and simulated samples were tested.The results showed that the water resistance,freezing point and color difference of simulated samples were improved after modification,and the compatibility with the original bone glue was good.In terms of mechanical strength,the anti-compressive strength and film hardness of modified bone glue decreased slightly,but the flexibility increased.In the evaluation of aging experiment,the modified bone glue has excellent performance in dry wet cycle aging.Compared with B72,its flexibility,tensile ratio and thermal stability are better,but the color difference of the reinforced sample changes more greatly,and the ultraviolet aging performance is poorer,so it is not suitable for outdoor color painting.(6)The FEVE/m-GO and modified bone glue developed in this paper were applied in the protection of color paintings of Xiefang Pavilion,Sanyou hall,Songxiu Pavilion in Qianlong Garden of the Forbidden City.FEVE/m-GO was used as the restoration material for the cracking and warping of pigment layer,and modified bone glue was used as the reinforcement material for the powdering of color painting.The results show that the restoration effect is remarkable,which provides a new idea for the protection of ancient architectural painting. |
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