Ancient coins were made from a variety of materials, including precious metals. On many of them, the time and conditions in which they stayed have left traces. However, there are many ways to clean coins.
The most common types of pollution of old coins are traces of earth, sand, and just ordinary dirt. To get rid of them, use a soft cloth or a brush dampened with soapy water. You can just gently dip coins into it. Let them lie there for a while. If after this procedure you find residual dirt, then try very carefully to remove the residual dirt with a soft brush. This method allows you to clean coins from any metal: copper, silver and gold.
It is very common to find coins with signs of oxidation. They are removed in different ways. Choose the method depending on the state of the coin and what metal it is made of. Specialists get rid of oxides, as a rule, by chemical methods. But they are quite affordable at home as well. If the condition of the coin causes you concern, it is better to contact a specialist. He will clean her with ultrasound.
Silver coins are recommended to be cleaned exclusively using a chemical method. In this case, various drugs and solutions are used. They are selected depending on the state of the coin and the type of oxidation. Take a close look at the color and type of oxides. If you notice a greenish coating, it means that the oxidation came from copper compounds. In this case, you will need a 5% sulfuric acid solution for cleaning. Place your coin in a china cup, then fill it with this solution. After that, start to heat slightly over low heat. The increased temperature will speed up the cleaning process. You can use 10% formic acid. The cleaning method is the same.
There is another type of plaque - horny silver. Its color is violet-gray. It usually appears on soft metals. This means that they cannot be cleaned with acid. If the plaque is thin, place the coin in a 5% ammonia solution. Watch the cleaning process very closely. The ammonia will soften the plaque. You can easily remove it with a brush.