Cultural relics protection has always been a hot topic, especially cultural relics such as bronze, pottery and wood lacquer, which are easily destroyed after being buried underground for thousands of years and cleaned up, such as salt damage. However, there are also good ways to eliminate salt damage... What exactly is salt damage? And how to eliminate it? The following Xiaobian will reveal the secret to you.
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In June 1974, a funerary pit was found near the Mausoleum of Qin Shi Huang, which was later determined by archaeologists to be the burial pit of qin shi huang mausoleum, and a large number of figurines were found in the later excavation and cleaning process, that is, the world-famous terracotta warriors of qin shi huang mausoleum. In addition to the terracotta warriors, archaeologists also unearthed some small hundred figurines, and after cleaning up, the experts also wrapped these hundred figurines on wet white paper, and finally sent them to the museum for preservation. Similarly, when cleaning up other Han Dynasty tombs, if pottery figurine experts are found, they must first prepare white paper and water, and then wrap the clay figurines tightly in three layers of wet white paper.
For this matter, some people wondered, why did they have to wrap white paper after the pottery figurines were unearthed? To answer this question, you need to first be shown a cultural relic. In the Qianling Museum in Shaanxi, visitors have found two pottery figurines with hairs on them, that is, many dense white flocculent crystals. Later, experts from the Qianling Museum said that the long hair of the pottery figurines is a salt crystal, because the temperature in the museum is high, resulting in the salt in the clay figurines being analyzed, and then attached to the surface of the ceramic figurines like long hairs.
Experts said that although the long hair of the pottery figurines is a normal phenomenon, it is strictly forbidden to occur in the process of cultural relics protection, because this will cause serious damage to the pottery figurine cultural relics, resulting in the weakening of the balance of the molecules in the material, and then make the cultural relics peel or weathering, resulting in irreparable destruction, so in order to better preserve the pottery figurine cultural relics, experts must first do one thing when unearthing, that is, wrap the ceramic figurine cultural relics with wet paper, and use academic expressions to remove salt damage.
The so-called salt damage, as the name suggests, is the harm of salt substances, the salt here is not our daily edible salt, but the metal ion or ammonium ion and acid ion combined compounds, such as copper chloride, calcium sulfate and sodium acetate. Pottery relics are buried underground for thousands of years, and all kinds of salt substances in the soil will penetrate into it, and the longer the time, the more they accumulate, and the cultural relics will also reach a balanced state in such an environment, so they can be preserved to this day. If once the cultural relics are cleaned out, this balance is artificially destroyed, so it is necessary to remove the salt damage and release the salt substances that penetrate into the cultural relics.
It is not difficult to remove the salt damage, but to use the chemical displacement reaction to decompose the salt substance. In the process of desalination, the most critical thing is to use the right paper, otherwise the desired effect will not be achieved. After a long period of research and practice, archaeologists have found that the rice paper in Anhui has the best effect, because the rice paper is extremely tough and can lock in moisture for a long time, so that the moisture will not evaporate quickly when wrapped. In addition, under the sunlight, the rice paper does not produce cracks after drying.
The most important thing is that there are many tiny wool on the surface of the rice paper, which can be deeply covered to every part of the clay figurine after wetting, even if it is a small crack and gap, and then use the principle of capillary network to dissolve and adsorb salt substances, not sparing every dead end. After the wet rice paper is wrapped, it should be placed in a cool place to dry naturally, and then continue to wet with water when it is drying quickly, repeat it 5-6 times, and then peel it off after the final rice paper is dried, so that the harmful salts in the clay figurines will also dissolve and discharge, at this time, you can normally pack the box to the museum for study or display, and finally have the conditions to strengthen the agent has a better effect.
The road to protecting cultural relics is a long way to go, and every link must be in place and there can be no mistakes, otherwise there will be abnormalities in the process of cultural relics preservation. Of course, there is no need to panic when there is a problem, but to think calmly and deal with it in a scientific way. For the long-haired pottery figurines of the Qianling Museum, the experts in the later period have now returned to normal after treatment, and we must also learn lessons from this, pay attention to the preservation environment of cultural relics, always pay attention to the changes in cultural relics, and put an end to the phenomenon of cultural relics destruction.
Resources:
From Cultural Relics Protection to Cultural Heritage Protection by Shan Jixiang, Publisher: Tianjin University Press
Wenlan Hairun Studio Editor-in-Chief Wen Xiucai, this article is written by: Special History Writer: Liu Lijiang's