Physical methods (including manual and mechanical grinding methods). Physical method can remove rust scale, verdigris, or greasy dirt on the metal surface, but rough operation is easy to scratch the workpiece.
Be affected with damp, basic copper carbonate is formed by chemical action in humid air. The reason is that copper reacts with oxygen, carbon dioxide and water in the air. Rust is the result of the combination of copper and water, oxygen and carbon dioxide, resulting in the substance Basic Copper Chloride, which is green in color.
Note:
1. The main component of rust is ferrous oxide, and its molecular structure is relatively loose. Therefore, the principle of expansion with heat and contraction with cold can be used to make part of iron rust fall off. However, when using this method, attention must be paid to adding a receiving vessel (e.g. a metal container such as a pot), and it is better to add some clear water.
2, the heating time should not be too long, generally strong fire heating for three or four minutes, take out and cover with a cold wet towel, rust will naturally fall off. Select heating method to remove rust. The object should be iron coins with good iron and shallow corrosion. Copper coins with severe corrosion and very fragile copper body must not be removed by heating method. Otherwise, copper that is already very fragile will not be able to withstand high temperature and will be fragmented and crushed to pieces.
3. Knife scraping method: When using Basic Copper Carbonate, attention should be paid to moderate severity. If it is careless, the copper will be scratched black and blue all over, and if it is serious, the whole copper body will be damaged. Therefore, if you are not sure, you cannot use it.