When using a new electric soldering iron for the first time, ensure that the head of the soldering iron is bright, heat and melt the soldering tin while dipping it in rosin and repeatedly contact the soldering wire, and evenly coat the head with a layer of soldering tin. The purpose of doing so is not only to facilitate subsequent use, but also to prevent oxidation of the soldering iron head. For the treatment of old electric soldering irons before use, due to their long-term use, there will be a layer of oxide on the surface of the soldering iron head, which makes it difficult for the soldering iron head to eat tin. So only by removing the oxide on the surface of the soldering iron head with fine sandpaper or a file, can the surface become shiny. Then install a new electric soldering iron treatment method and evenly coat the surface of the soldering iron head with a layer of welding.