As we know iron is a metal that is easily corroded in the open air. The iron will be brown due to the corrosion of the iron surface. If this is allowed then this corrosion will spread to the deeper layers of the iron.
The continuation of this corrosion must be prevented because if left unchecked, the iron will be consumed by corrosion.
In everyday life, there are various ways to prevent corrosion, including painting or smearing the surface of iron with oil, or blackenning before storing goods made of iron in a warehouse.
On the surface of the iron in general will experience corrosion in the open air so that on the surface of the iron will form an oxide layer, namely iron oxide.
In large iron goods industries that will undergo further processing, the oxide layer must be removed. Of course, the method is not done manually but using an electrochemical process.
This electrochemical rust removal process is basically having a metal object treated as the negative electrode while another object that is normally rust resistant is treated as the positive electrode. Then the two objects are put into a chemical solution and electrified. With this process, the oxide layer on the iron surface will decay and the iron will become clean.
To see this process, see my video below:
