Light aging of madder on silk

To simulate the natural light-aging process of the madder on silk during cultural relics exhibition,a series of systematic tests were carried out.Fluorescent UV lamp,halogen lamp and white LED were chosen in the light aging experiments.Three kinds of fading curves were gained under irradiation of different lamps,and HPLC was used to analyze the internal rule and mechanism of the light aging of madder.The results indicated that madder was destroyed seriously under the irradiation of UV light;madder faded a little slower under the irradiation of halogen lamp than LED lamp.Identification test shows that purpurin is the main coloring matter in madder from Shaanxi,and the change of its area of peak in HPLC can well reflect the degree of light aging.