Reviving an oxidized tip

Predicting the future: this will not survive past a few uses, and the tip will wear fast.

The thing that protects it, is iron plating. That will be completely gone after your hard work.

Did you try it too? What increases the wearing speed?
It still allowed me to finish a long soldering session, so that was still better than having to toss it to the bin.

Quality solder tips are plated with chrome (over the iron plating over the copper core.)

My understanding is that electrolysis is an effective way to remove chrome from a surface!

So while you may have removed the thick oxidation, you likely removed the protective chrome layer as well.

FYI, This is a cross-section I got from Weller.

It's not clear to me what the "pre-tinned" tip in this case is. However, my assumption is that the layers wrap around to the tip (yellow section).

FYI, Weller sells a polish bar you can use to scrape oxidation off of a tip in bad condition. (Just make sure the tip is cold when you do!) For a video on tip maintenance, I accelerated the oxidation of a tip. I was able to recover it with the bar. (but I would probably only use it until I got a replacement.) Nice to have when you're in a pinch, but I would instead recommend keeping a back-up tip on-hand!

My understanding is the solder tinning only sticks to iron so that is what is right at the tip.. Further up, the iron is protected by chromium and nickel but the iron right at the tip is only protected from rusting by solder tinning. Rust happens quickly at high temperature - it eats away the iron and solder doesn't stick to rust, which is why tinning is so important.

Copper gets heat to the tip, Iron protects the copper from oxidation and wear, solder protects the iron from oxidation. The best refurb method would remove all rust from the iron tip without removing any solid iron.

I don't know how to fix this, but curious what you try, since I have a rust issue to deal with too (got some rust on a flat surface in the shed, because I forgot to oil it this winter : ( I've wiped off a lot just scrubbing with an oiled cloth (and also tried with isopropanol), but there's still a faint layer of oxidization on some parts of it, and I need it as completely flush and clean as possible (no sanding, the surface is machined to be flat, and I want to keep it that way!).

Interesting! What is special about the "polish bar"? How does it compare to using sandpaper, a file or steel wool?

I don't know what its composition is. However, I suspect it is softer than the plating but hard enough to remove oxidation.

The problem with all three of the methods you listed is that they'll take the protecting plating off the tip along with the corrosion. This is bad because then you're almost instantly oxidizing layers that were not meant to be exposed to oxygen, much less oxygen, while heated.

So sandpaper or steel wool can be helpful as a temporary fix if you have zero other options. But once you use them, consider the tip dead and needing replacement.

Personally, I'd rather have a spare tip around than the polish bar. Tips are consumables that should be replaced periodically anyway.

I had same understanding. I just submerged the tip, so I don't know if chrome would be affected, but as I understand metal oxides get reduced through electrolysis, so I'm not sure what mechanism could cause damage to the metal components.

That polish bar sounds like it might work on rust spots, or maybe a brass scraper. Maybe you could try polishing it with some scratch removal compound meant to fix vehicle paint scratches. I've used it to remove scratches from DVDs but haven't tried it on rust spots.

Do you have access to DeoxIT?

Their claim is that the compound can break up the oxidation's bond to the pure metal and separate them. (I'm not sure how to prove or disprove that.)

That sounds like what you're trying to do.