How should I maintain my soldering iron tips?

I am having trouble with my soldering tips. It seems that I have to use a tip tinner way to often. If I let the iron sit for any small amount of time even while I place another component for soldering I have to clean the oxidation off it before it will even melt solder. My question is….I use regular tap water on my sponge could this be the problem with my tip oxidizing so quickly? If I used Distilled or Deionized water will it help in keeping my tip clean? If so which is best to use Distilled or Deionized?

I think there are at least two separate issues here– the need to wipe the tip before use, and the need to “re-tin” it.

For what it’s worth, we use temperature controlled (not wattage controlled) irons on the line here and replace tips perhaps once every 3 years or so due to physical wear. The tips are not resurfaced or re-tinned at any time.

If you use a constant power iron (fixed wattage, or variable wattage) and leave it on overnight you will literally burn the tip and need to resurface it, probably using sandpaper, and tinning will be easier with a purpose-designed tip tinning compound. Usually a replacement tip will cost a dollar or two, and it is a lot easier just to replace a burned tip than to try to resurface it.

In ordinary soldering, the tip should be wiped before each use. The solder itself will oxidize a bit, especially if you have a “hot” iron and not a temperature-controlled one. For example, if I were using a fixed-wattage pencil iron I would expect to wipe the tip
before soldering each component, and even DURING the soldering of things like ICs with a lot of connections. In our production work we will install 5 or 6 components at a time, and wipe the soldering iron tip when we begin soldering.

Wipe the tip by drawing it quickly across the surface of a damp sponge or rag. You should see a clean, shiny surface on the tip. You shouldn’t need to add solder to the tip unless you fail to get a shiny solder surface with wiping. And don’t wipe the tip after you use it– any excess solder on it will be wiped off next time, and it will serve to protect the tip from oxidation between uses.
The wiping sponge is moistened with distilled water, but not because of any direct affect on the soldering iron tip– over time, the water evaporates and tap water (also de-ionized water) will leave behind a bunch of minerals or “scale” which harden the sponge and
make it more difficult to use.

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