The Research On Concentration Prediction Of The Component Of Mixed Mineral Pigments

In the process of the preservation and restoration of Dunhuang murals,first of all,in order to record the original information of murals completely and accurately,it is necessary to identify the minerals,pigments and their contents in the wall paintings.The hybrid method of mineral pigment component analysis including X ray diffraction.The process of X ray diffraction is complicated and it's needed to detect and analyze each kind of mineral pigment mixture,and the range of the detection is limited.The mixed mineral pigments were analyzed by using the method of derivative spectrum,only need to calculate the calibration curves for each mineral pigments respectively,without to calculate and analyze each kind of mineral pigments of the mixture.The calculation process is simpler than X ray diffraction,and the range of the detection is bigger than X ray diffraction.This paper uses three kinds of mineral pigments(azurite,malachite,cinnabar)to conduct the experiment,mixing of mineral pigments.Through a mixture of mineral pigments with different concentrations,the first step is to calculate the color intensity of the content of the mixture,then to fit the data between the color intensity and content.After that,to get the fitting function of each of the three kinds of mineral pigments,also can be called as calibration curve.The calibration curve describes the law of mineral pigment in the mixing,so we can use the calibration curve to find the corresponding content value through the color intensity value,so we can achieve the purpose of mineral pigment content prediction.The experimental data shows out that the differences in color ability of different mineral pigment.The color ability of the three mineral pigments from high to low is:azurite,malachite and cinnabar.From the content of the calibration curve prediction of three kinds of mineral pigment of the 22 mixed color patchs,it's found that the error of the results of prediction of the malachite and azurite both are less than 5%,and the error of the prediction results of cinnabar is in the range of 5%-10%.In summary,using the method of second order derivatives of K-M function can successfully predict the content of azurite and malachite in the mixed mineral pigments,so it is of great importance for the preservation of the cultural relic.