How can I prevent my soldering tip oxidising while I'm using it?

Question

I have a temperature-controlled soldering iron. When I use it above 250°C, the tip quickly dulls and won't take solder. By "quickly" I mean "within 20 seconds". I have to clean the tip with copper wool or a damp sponge literally between every joint.

I am using leaded solder, and I only solder at these higher temperatures when the wires/contacts are large and difficult to heat. Or when using desoldering wick, which amounts to the same thing.

Is my tip just of poor quality? I have tried different tips, but maybe they just all suck. Should I be using a more expensive tip?

EDIT: I'm using a MarkEthan SMD Rework Station, with generic Ebay tips, and "AlphaMetals 8-Sn60Pb40" leaded solder.

Answer 1

Some tips which may help:

Do not use abrasive cleaning methods on a new tip. Most tips have a protected layer when new and you don't want to damage that.

Make sure to use A LOT (Note: capitals AND bold) of solder to tin it. I make a puddle and keep it in there for some time, regularly refreshing the solder or start a new puddle as the solder will 'burn/oxidize' after a while. In the beginning you will see that the solder does not 'stick', like water on a fat surface it stays away form the tip. Only stop after the solder sticks to the tip like water does to glass.

I had the very bad habit of cleaning the tip when done with a solder joint. Wrong! The best thing is even to put some more solder on the top when you are done. Make sure to get rid of it before you start a new joint again as the solder will have gone 'bad' (oxidizes). So the procedure is:

1. Clean tip
2. Solder using new solder
3. Put solder on tip
4. Put iron away for a while.

Answer 2

You're probably not still looking for an answer, but if I were seeing this with one of my irons and I trusted I'd cleaned it properly I'd start to worry that the tip wasn't achieving the target temperatures and was actually hotter than intended.

Answer 3

I had the very same trouble with soldering tips going brown (or black), and then losing the ability to pick-up solder - and remain clean. The problem here, I believe, lies with the soldering-tip temperature. If the tip temperature is too high, oxidation occurs. How I overcame this problem - was to place a variac in series with the electric soldering iron. in this way, you can adjust the variac control, and get a 'feel' for the precise temperature that will create a good solder flow, and yet maintain a reasonably clean iron tip.

I only use cotton cloth to wipe the iron tip, as steel wool removes the fine coating of iron. This seems to be much more critical on any soldering iron that does not have any form of temperature - control feature. I have several soldering irons, and they all get plugged-in to a variac.