To keep the original appearance of bronze sculptures, there is a problem of collection and storage. After long-term corrosion and oxidation in the underground, the texture of bronze sculptures is not strong. Especially the semi detached bronze carvings are even more vulnerable than porcelain. Therefore, it is very important for investors to properly preserve the bronze carvings and prevent them from being damaged after excavation.
The unearthed bronze sculptures are often muddy with mud rust and unclear decorative patterns. Proper cleaning should be carried out to let the soil fall off by itself, and then gently brush with a small brush. When encountering soil rust that affects the decoration, small bamboo sticks can be used to slowly remove the rust. Never use a copper brush or a hard brush to brush it, let alone use a sharp tool to clean and polish it. Otherwise, it will destroy the bronze carving and lose its collection value.
So how to protect and maintain the bronze carving?
① Silver oxide method. Silver oxide is used to contact with cuprous oxide to seal the exposed surface of cuprous chloride, so as to control the corrosion of copper carving. First, the powdery rust was removed by mechanical method, and the gray white wax like substance cuprous chloride was exposed. Then, silver oxide and alcohol are mixed into paste and coated on the surface of cuprous chloride and placed in a humid environment to form cuprous oxide and copper chloride to cover the surface of cuprous chloride. Both of them are stable salts, which can be operated for many times until there is no corrosion spot of powdery rust in the high humidity environment. It is suitable for local etching of metal objects.
② Benzotriazole method. Benzotriazole is a heterocyclic compound, which can form a stable complex with copper and its salts. It can form an insoluble and fairly strong transparent protective film on the surface of copper alloy, which can inhibit and stabilize the bronze carving disease and prevent the erosion of water vapor and air pollutants. Using distilled water and organic solvents such as toluene and * * to remove the dirt and oil on the surface of bronze carving, and then immerse in benzotriazole alcohol solvent to form complex protective membrane. However, benzotriazole is easy to sublimate and lose its protective effect when heated. Therefore, a layer of polymer material should be coated on the surface of the bronze carving to make a sealing film. ③ Alkali immersion method. The corroded bronze sculptures are immersed in sodium bicarbonate solution, so that the chloride of copper is gradually converted into stable carbonate of copper, and the chloride ions of copper carvings are replaced and transferred into the immersion solution. The immersion solution should be replaced regularly until there is no chloride ion in the immersion solution. After that, the utensils were repeatedly cleaned with distilled water to remove the lye and sealed after drying. The alkali solution only extracts chloride and retains the colorful Malachite corrosion layer, which does not damage the original appearance of the bronze carving. The disadvantage of this method is that the replacement reaction time is long; in addition, chloride is not only attached to the surface of rust layer, but also has penetrated into the deep part of the crust.
