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I have been using a Weller WLC 100 for about 10 years, and I have always used this conical tip from Apex Tool Group: https://www.mouser.com/ProductDetail/apex-tool-group/st-7/?qs=fKX4t1ubQE95bthTEmHMHA%3D%3D&countrycode=US&currencycode=USD

image of the link above

Recently I have been using tin/silver/copper (Sn96.5Ag3Cu0.5) lead free solder -- I've been using this solder: https://www.digikey.com/en/products/detail/multicore/796065/2498924

image of the link above

I am able to use a new tip and this solder for about 3 - 4 months before the tips become dull and grey and no longer have solder cling to them. After that, they will melt the solder, but the solder will ball up and just fall off.

From reading other posts here, it appears that perhaps I am cleaning the tip too abrasively and removing the iron plating. For instance, my soldering routine is:

  1. Turn on iron/let solder previously left on tip become molten
  2. Wipe off molten solder on damp sponge
  3. Do soldering
  4. When tip appears to be dirty, wipe it off on a sponge
  5. When tip appears very dirty, pull it through my copper scouring ball
  6. When soldering done, cover tip in solder
  7. Turn off iron

I think on step #5 above, I may be damaging the tip. On the other hand, when I use leaded solder I don't have any problems, and I have use the copper scour ball for a long time with no issue.

I have also written to Weller and they could not make any suggestion about why my tips were ruined.

Attached is an image of my soldering station, which can only control temperature by potentiometer (I keep knob just below 5 as that appears to melt solder easily, and a bit below takes solder too long to melt). Also attached is an image of two "dead" tips.

enter image description here enter image description here

  1. Can anyone suggest why my tips become dull when I use this lead-free solder, and why solder will not cover them any more?
  2. Is it possible to re-tin my tips? If so, how?
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    \$\begingroup\$ Id recommend metal wool instead of sponges to clean the nose. Sponges with water cause the nose to cool rapidly and this causes it to break faster. Also using wool, I think, you will be scaping away the rusty surface/nose of the iron, and the solder will be able to stick to it better. \$\endgroup\$ – Christianidis Vasileios Apr 27 at 12:03
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    \$\begingroup\$ @ChristianidisVasileios: 1. They are called "tips" in English. 2. A sponge should be nearly dry. Get it wet, then squeeze it out. Squeeze it more, until no more water comes out. It will feel nearly dry to the touch, but still be damp enough that it won't burn - and it won't damage the tip. \$\endgroup\$ – JRE Apr 27 at 12:36
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    \$\begingroup\$ 3. The problem in the question isn't caused by water. Cooling causes cracks which cause the tip to be "eaten away." It would be jagged and sharp edged. \$\endgroup\$ – JRE Apr 27 at 12:38
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    \$\begingroup\$ The tips look physically fine. I'd get a tin of the Multicore® Tip Tinner/Cleaner recommended in the datasheet of the solder and clean the tip with it. "Balling up and rolling off" happens when the tip has a coat of oxidation on it. The tip cleaner should remove it. \$\endgroup\$ – JRE Apr 27 at 12:43
  • \$\begingroup\$ I have noticed the same, but since it has been years since i've last used leaded, I thought it is normal lol. I use metal wool to rub off the soot and plenty of fluxed solder to wet the tip before soldering. but it gets dull fast after that. IMO, the tip is fine, but the leadfree solder tends to form dull thick oxide as compared to the thin shiny layer on PbSn \$\endgroup\$ – tobalt Apr 27 at 13:43
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Your routines are sound, I do the same as you except the #5 - I don't use the copper balls but they shouldn't damage the tip.

Most likely it is oxidation, which will contain flux and various other chemicals that stick to the tip, in which case a sponge might not get rid of it all.

There's something called "solder tip cleaner/activator" that you can try. Basically a little box with some cleaning chemicals, sold by Weller among others - check this video. This isn't something I use every day but mostly when picking up an old tip that hasn't been used in a long time.

Apart from that, it might of course be some issue with temperature or forgetting the station on etc, which also turns the tips gray and useless similar to what you describe.

Also, some 3-4 months of frequent soldering is about what I would expect before changing tip. If you haven't used the iron much then it should naturally last longer.

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