From
Ceramic Mug Group,Caitao was first found in the Neolithic cultural site of Yangshao village, Mianchi, Henan Province in 1912. It is an outstanding art craft in ancient China. Because of its long history, exquisite technology and scientific research value, it has a very high collection value. In particular, the colored pottery of Majiayao culture in Qinghai and Gansu areas in the upper reaches of the Yellow River is famous for its beautiful shape and gorgeous patterns. The more famous ones in modern times are Yunnan colored pottery with exquisite workmanship and beautiful patterns. How to maintain the painted pottery is the concern of some collectors. Next, the author from the main diseases of pottery, cause analysis and treatment of three aspects of the shallow view.
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I. main diseases of colored pottery
In the long-term underground burial, colored pottery is eroded by various physical and chemical reactions with different intensities. The unearthed painted pottery has some hard dirt on the surface of the pottery, some even cover the whole painted pottery, which affects the appreciation and research of the decorative pattern of the painted pottery. After the pottery was unearthed, some changes took place after encountering air, especially after the pottery buried in the salt and alkali land was unearthed for a period of time, some of its surface was white, some of its surface was peeling off, some of its surface was peeling off, some even its body was loose and peeling off, which seriously damaged the pottery.
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II. Analysis of the causes of the diseases of colored pottery
The colored pottery is made of red clay at 680 degree to 1000 degree. Under normal condition, the physical and chemical properties of colored pottery are relatively stable, and it has good mechanical strength and water resistance. However, due to the relatively loose structure of the ceramic body, the ceramic has a strong adsorption. The buried time of painted pottery is more than 3500 years, and some even reaches 6000 years. In these long years, the soil contains a large number of soluble salt and alkali substances of calcium, sodium and magnesium plasma, which are continuously absorbed into the body of pottery and accumulated, so the unearthed colored pottery has a high content of salt and alkali. Some calcium and silicon compounds in the soil are firmly adsorbed on the surface of colored pottery, which will form white, hard and water-insoluble hard scale to cover the surface of colored pottery. After the pottery was unearthed, its preservation environment has changed greatly. The unearthed painted pottery is greatly affected by the surrounding humidity and temperature. Some salt and alkali substances in the pottery body will have physical and chemical reactions after contacting with the water and other substances in the air. When the surrounding humidity is high and the temperature is low, the salt and alkali components in the ceramic body will absorb moisture and dissolve; when the surrounding humidity is low and the temperature is high, the salt and alkali components in the ceramic body will lose water and crystallize. When the salt and alkali components are separated from the surface of the pottery, the surface of the colored pottery will be white. At the same time, the phenomenon of "hot expansion and cold contraction" and "dry expansion and wet contraction" will occur repeatedly, which will make the structure of pottery loose, the surface of pottery peeling off, and the decorative pattern of colored pottery peeling off.Stoneware Coffee Mugs
III. treatment methods for diseases of colored pottery
One is to strengthen the loose colored pottery. For some loose colored pottery, the first step is to strengthen. Generally, a new polymer PS with good compression resistance, dry and wet cycle resistance, freeze-thaw resistance and no influence on the color of the pottery can be selected as the reinforcing agent. Reinforcement shall be carried out from the surface to the inside. A certain amount of low-speed PS material was absorbed by a straw, and then dropped to the loose part of the ceramic body one by one, so that the PS material slowly penetrated into the ceramic body. Then gently pinch with hand to check whether it is fixed. After it is fixed, spray, dry and spray again, repeatedly until PS material can not penetrate.
The second is to dilute the salt and alkali components in the body of pottery. Removing the salt and alkali components is the key link of maintaining the painted pottery. Generally, the physical principle of ion permeation can be used to dilute the salt and alkali components in the painted pottery. For the pottery with good firmness and white surface, it can be soaked in cold boiled water or distilled water for a day or two, during which water should be changed for many times. After the salt and alkali components in the pottery are diluted thoroughly, it can be dried in a dry environment. It should be noted that the water used should not be tap water, because the tap water is put with bleaching powder or liquid chlorine in the production process, and the hypochlorite ions formed in the water are oxidizable and easy to corrode the decorative patterns of colored pottery. In addition, the water quality in some areas is relatively hard, and it is easy to scale on the surface of painted pottery. For the loose colored pottery, it is necessary to reinforce, then dilute, and finally reinforce.
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The third is to remove the hard dirt on the surface of colored pottery. Some salt and alkali substances, such as calcium carbonate, which are difficult to dissolve in water, are attached to the surface of painted pottery after it is unearthed. These substances cannot be removed by washing and dilution. In general, the chemical and physical properties of these attachments are relatively stable, and they do not harm the painted pottery. As long as they do not affect the decoration, they generally do not need to be removed. When there are too many adherents that affect the decoration of colored pottery, strong acid without oxidization can be selected. They can be removed by the principle of acid-base chemical reaction and chemical reaction between strong acid and weak acid, weak alkali salt. When descaling, a certain amount of dilute hydrochloric acid can be suck on the surface of the painted pottery, and the attachment will produce hissing sound and foam, accompanied by pungent odor. After removing the attachment, rinse it with clear water, then with soda water and residual hydrochloric acid, and finally rinse it with clear water. If there is a small amount of attachment that can not be removed by hydrochloric acid, hydrofluoric acid can be used. The use method is the same as hydrochloric acid. It should be noted that the acid and alkali resistance of colored pottery is relatively poor, and the "fire" of dosage and time must be taken into account when descaling. After removing the attachments on the surface of the painted pottery, the decorative patterns can be reinforced according to the situation.
