Research On Light Scattering And The Fading And Appearance Of Cultural Relics Painting

Coloured relics unearthed in China,including building coloured drawing,ceramic painting,mural paintind,on which the vivid colour and artistic design represent the ancient art crafts,human intelligence and historical progress,have historical value,artistic value and scientific value.However,these age-old relics have suffered a series of deteriorations inducing the fading of painted layer,enven faded immediately when unearthed due to the unreasonable protection measures or external factors from relics itself.It is important to repair the faded coloured relics,which recored the imformation about ancient China in historic,religious and aesthetics culture.In addition,it is an essential scientific problem to research the fading mechanism of coloured relics providing the restoration protocol for faded colured relics.It is widely be lived that the fading mechanism of coloured relics is concered with the oxidation and decomposition of pigment.While,the pigment in painted layer used in ancient China are inorganic mineral pigment,which is stable chemically under normal condition.In general,it is never persuasive that the fading of ancient relics attribute to the oxidation and decompostion of pigment.In fact,there are soil particle adhere to the surface of coloured relics forming scattering sites.We propose that the fading of coloured relics induced by these particle scattering,which reduce the light absorbtion of painted layer.Additionally,binder materials in painted layer used in ancient Chian are organic matter and was degraded inevitably generating cracks in painted layer.The presence of these cracks increase the intensity of sacttering and decrease the light absorbtion to incident light in painted layer inducing the lighter color of painted layer.To sum up,we think that scattering derived from the structure change in painted layer is on of important reason for the fading of coloured relics.In practice,the faded coloured relics could be restored by filling the colorless liquid with higher refractive.It is result from the decrease of scattering in painted layer due to the increase of light absorbtion and the decrease of homogeneous in refractive through filling the air interface.To prove above viewpoint,in this thesis,faded painted layer with sacttering was prepared to simulate the different stucture in ancient painted layer,through analysing the changes in colour attribute,mophology and optical properties to research the effect of scattering on colour fading and showing.In this thesis,there are three research works were carried out,as follows.Firstly,study on the effect of particle scattering from the surface of colored relics on the optical property of coloured relics.To reveal particle scattering inducing the fading and showing of coloured relics,the model of particle scattering was built and the scattering of nano particle was controlled throug loading nanol TiO2 particle on coloured paper.In this chapter,three-primary coloures(red,yellow and blue)paper as the coloured painted layer,on which TiO2 particles were generated in situ on the fiber of paper,prepared the simulated paper sample with particle scattering.The effect of TiO2 particles content on the scattering intensity and paper color was studied through controlling the loading capacity of TiO2 particles on coloured paper.The relationship between particle scattering and paper colour was revealed through SEM characteristic and combing the mophology,scattering and optical property in colour.The results show that TiO2 particles scattering on paper induced the lighter color of paper,and the more TiO2 particles loaidng,the more roughness paper has and lighter colour of paper present.The faded paper could be showed after inducing the difficult volatilization of ionic liquid[BMIm]PF6 with higher refractive index.With limits,the more inoic liquld induced,the more holes among TiO2 particles filled leading to the smoother of paper surface and the notable showing result of faded paper.Above results indicate that particle scattering has evidently fading effect on the colour of paper and the eliminate of scattering colud show the faded colour of paper.To reveal the machenism of scattering on colour lighten,the scattering model with shorten optical path was set up.The multilayer paper with scattering were compressed togeter to forming a simulated sample with multilayer scattering,under which the fluorescence intensity of a paper with fluorescence was detected before and after treated by ionic liquld[BMIm]PF6.The results show that the intensity of fluorescence increased with the dosage of ionic liquld introduce into the paper within limits.The less layers of paper,the weaker reflectance of paper.Combing above results,it could be concluded that light scattering reducing the optical path of incident light is the essential reseason for the lighter colour of painted layer.Secondly,study on the effect of cracks scattering on the optical property of coloured relics.The model with crack scattering was built by calcining method to degrade the binder material in simulated painted layer combing the properties of simulated painted layer in mophology and coloure optics before and after calcining and filling the cracks to reveal the fading and showing mechanism of coloured relics caused by crack scattering.In this chapter,mixture of gelatin and ochre pigment was brushed onto the soil embryos to paint a coloured relics.The simulated painted layer with and without crack scattering were obtained by calcining to degrade the organic binder and filling the simulated painted layer with and without crack.The results show as follows:(1)after calcining,the degradation of gelatin in simulated painted layer represent the degradation of binder in coloured relics,and the painted layer has cracks and a lighter colour.(2)When the calcined simulated painted layer was treated by ionic liquid[BMIm]PF6,the crack was filled.Simultaneously,the reflectance of simulated painted layer decreased more with more ionic liquid induced within limits and the faded sample could be showed more markedly.(3)Using ionic liquld to fill the crack for showing,the optical property of simulated painted layer is related to the dosage and refractive index of ionic liquld.The bigger dosage and refractive index of ionic liquid,the more outstanding showing results.The colour of painted layer after showing would be deeper than the original painted layer because of the excessive filling of ionic liquid into painted layer leading to both original crack and crack direved from the degradation of gelatin were filled,while,further excessive filling forming high-gloss phenomenon,as result the colour of painted layer after showing would be lighter than the original painted layer.Thirdly,study on the showing application in ancient coloured relics based on scattering.In this chapter,ancient cocoured relics with different materials were showed to indicate the universality and feasibility in the restoration of relics by eliminating scattering.The fragments from faded Buddhist paper in Tang Dynasty,sunk panel drawing with white spots of Puzhao temple in Yuan Dynasty and mural painting of Zang Huai liang tomb in Tang Dynasty representing ancient relics with different materials were treated by ionic liquid,respectively to verify the showing feasibility by eliminating scattering.The results showed that relics with faded colour or pattern possess particle or crack scattering phenomenon,which was filled by ionic liquid to reach the showing of letter,colour or pattern.It is universal and feasible to restore the blurry relics by eliminating scattering.