Tinning the Tip of a Soldering Iron
As you use your soldering iron you may find that the tip starts to adhere less well to the solder or it starts to show little black sports or discoloration perhaps even a rusty appearance. When that occurs the tin coating on the tip is beginning to deteriorate and you need to refresh it by tinning the tip.
In order to do so, we have to break up whatever kind of oxide coating is forming on the tip. We use different types of materials. You can use a block of sal ammoniac which can generate ammonia vapors to disintegrate the oxide layers. Once ammonia begins to generate vapors, you should flow some solder to the tip and this will wear away any of the oxides that have formed and when you finish you’d better wipe the iron on the wet sponge so that you can have a nice, brand new, shiny tip again.