Laboratory studies of the commercial acrylate emulsion consolidating fragile archaeological lacquer films
Liujiawa site in Chengcheng County,Shaanxi Province was the capital site of Rui State in the Spring and Autumn Period.Its discovery and excavation provides a typical case of the development and evolution of the vassal states of the Eastern Zhou Dynasty,which is of great significance to fill in the blank of the late history of Rui State and promote the Zhou-Dynasty archaeological development of the eastern Guanzhong region.Wooden lacquerwares unearthed at Liujiawa site are mainly related to musical instruments.Most of their wooden bodies have been corroded and only lacquer films remain(most are broken and rotten).Current research has initially explored suitable conservation materials for the unearthed rotten lacquerwares from north China,but research on evaluation methods for the conservation effect is limited,and there are also some challenging puzzles,such as low instrument precision and large dispersion of test data.To evaluate the conservation effect of several commonly used acrylate emulsions which were difficult to distinguish in previous research,this work was carried out to select the optimal conservation material and concentration and study the process sequence.The commercial acrylate emulsions AC33,B60A,MC76 and SF016 are commonly used as consolidants for fragile archaeological lacquer films.However,due to the limitation of preservation conditions and sampling restriction,the reinforcement effects of these acrylate emulsions on lacquer films,especially the essential mechanical properties,have not been assessed(due to the lack of suitable test method).Here,the bending strengths of archaeological lacquer films before and after consolidation were tested by thermomechanical analysis(TMA)with its excellent characteristics of being nondestructive and accurate.According to the degree of improvement of the stress-strain of the treated lacquer films,the reinforcement effects of the four acrylate emulsions were quantitatively evaluated.In combination with the scanning electron microscopy to observe the changes of holes and fissures on the surface and the section of lacquer films before and after reinforcement,as well as the film-forming situation of the four acrylate emulsions,their conservation properties were demonstrated.The results show that the stress of the treated lacquer film increased by 56％-3 511％,and the strain increased by 103％-3 876％.Among the four acrylate emulsions,20％AC33 had the best reinforcement effect and 20％B60A had the best toughening effect,but MC76 and SF016 performed relatively poorly.20％is the best concentration for the four acrylate emulsions,in that at this concentration the holes and fissures of lacquer films were completely filled and the acrylate emulsions were able to form a continuous film without excessive accumulation.Compared with previous research,this study has made expansions in the following two aspects:1)a new instrument for the study of rotten lacquer film is proposed—thermomechanical analyzer was used for the first time to test the residual mechanical strength of extremely fragile archaeological lacquer film and evaluate the mechanical enhancement effect of reinforcement agents;2)a new characterization method to study fragile archaeological lacquerware is initially established—the penetration and film formation of reinforcement agents,surface and profile morphology of the lacquer film and mechanical strengths before and after reinforcement,were systematically studied.This research successfully evaluated the conservation effect of four commonly used acrylate emulsions,which were previously difficult to distinguish,to select the optimal concentration for use,providing a new evaluation method and an important reference for the scientific selection of materials for the conservation and restoration of rotten archaeological lacquerwares.
万方数据
维普
