Research Of Chemical Cleaning Technology Of The Immovable Historic Stones

Yungang Grottoes, one of the first batches of important heritage sites under state protection published by the State Council in1961, locate in the west of Datong, Shanxi province. It’s one of the largest grottos in China and also in the world, which is famous for its stone carving art. In2001, Yungang Grottoes were put on the list of directory of world cultural heritage. However, under the impact of various natural and anthropogenic factors for over1500years, Yungang Grottoes are suffering all kinds of pollutions and destructions. As a part of state science and technology support program, how to conserve and restore Yungang Grottoes is a pretty important issue. This thesis will explore methods for chemical cleaning of large immovable stone historical relics, aimed at drafting a standard cleaning protocol. This project is the primary part of "Study on the cleaning technology of noxious pollutants on the grottoes, National Technology Support Project of China", whose issue number is2009BAK53B05. This study also gets support from "special research foundation for historical relics of Zhejiang province", whose foundation number is2010-264.According to the deterioration investigation taken by our research group, there are12kinds of typical pollutants in Yungang Grottoes, including black smudges caused by smoke, dirt and dust, rusty spot, mineral crystallization, oil, resin, paint, scrawl, microorganism, water spot, concrete and gypsum. Details have been described in previous published paper. For the first time in the modern history of Yungang Grottoes protection, our investigation provides a comprehensive description of pollutants in Yungang Grottoes. Our deterioration investigation not only provides a scientific basis for Yungang Grottoes conservation and restoration, but also provides a valuable experience for stone historical relic deterioration investigations all over the world.In this thesis,5kinds of pollutants including rusty spot, organics spot, mineral crystallization, resin and paint are chosen to be studied. According to the analyzing of certain samples picked up from Yungang Grottoes by SEM-EDAX、XRD and FTIR, we can make a full-scale description of them. After familiar with their microstructures and compositions, we imitate similar samples in lab for further study.A new type of cleaning ingredient containing crystallization inhibitor that suitable for stone is proposed here and operating conditions are optimized; On the basis of lab experiments and locale practices, a standard cleaning protocol using for large immovable stone historical relics is drafted, which is the first official cleaning protocol in related fields in China.