Seeking Advice: Persistent Blackening of Soldering Iron Tip

Thread Starter

denni

Joined Jul 18, 2023
21
Hello Folks,

I'm hoping to gain some insights about an issue I've encountered with my soldering iron. Despite being a relatively new purchase - I've had it for just two months and used it on 5 to 10 occasions at most - the iron's tip, or "pin," has unfortunately turned black.

I've made several attempts to restore its original color using a brass sponge (you can see it in the attached photo) but to no significant effect. I've experimented with cleaning the tip both when it's hot and cold, but neither method seems to have improved the situation.
1689707275702.png
While the tip continues to melt solder, I've observed that it's taking increasingly longer to do so. Given the current state of the soldering iron tip, I'm puzzled whether it's already worn out and needs replacement, despite its recent acquisition and minimal use.

I would greatly appreciate your thoughts on this matter. Is there a need to replace the tip, or could there be another solution I might be missing?

Thank you in advance for your guidance and suggestions.
 

Ian0

Joined Aug 7, 2020
9,503
Are you using lead-free solder? Some tips blacken very easily when using lead-free.
Are you running it too hot? 120°C above the solder melting point is ideal.
When you are not using it, does the tip touch the metal part of the holder?
 

MrChips

Joined Oct 2, 2009
30,488
After cleaning the tip on the brass sponge, melt solder all over the tip until the tip is shiny again. This is called "tinning" the tip.
 

MrChips

Joined Oct 2, 2009
30,488
What type of solder are you using?
Is the soldering iron temperature regulated?
As Ian says, don't set the temperature too high, about 120°C above the melting temperature.
 

MrChips

Joined Oct 2, 2009
30,488
The picture you posted gives no indication of the type of solder.
Make sure that you can identify the solder type.
 

bassbindevil

Joined Jan 23, 2014
818
The solder will be lead-free because it is cheaper. And the quality of the tip may not be great. And the brass sponge might just be copper-plated steel or something; check if it's magnetic or not. I've found real brass sponges at the supermarket.
 

Thread Starter

denni

Joined Jul 18, 2023
21
After cleaning the tip on the brass sponge, melt solder all over the tip until the tip is shiny again. This is called "tinning" the tip.
Thank you for your insightful responses. In an effort to apply your advice, I've created a video where I mirror your steps exactly. The process involves cleaning the soldering iron tip using a brass sponge, followed by an attempt to melt solder over the tip.

Here is the video link that i uploaded on youtube cause i wasnt able to upload it here :

Interestingly, the solder takes an unusually long time to melt, despite the iron being heated to 360 Degrees Celsius. Moreover, instead of adhering to the iron's tip as I'd expect, the molten solder forms small balls that drop onto the silicone mat on my worktable.

I'm at a loss as to why this is happening and am hoping to get your insights. Could there be a flaw in my technique that I'm missing? I would greatly appreciate any constructive criticism and guidance to help me understand and rectify this issue.

Looking forward to learning from your expertise.
 

Thread Starter

denni

Joined Jul 18, 2023
21
The solder will be lead-free because it is cheaper. And the quality of the tip may not be great. And the brass sponge might just be copper-plated steel or something; check if it's magnetic or not. I've found real brass sponges at the supermarket.
Could you please review the video I shared in my previous post as a response to @MrChips ? I'm wondering if there's a possibility that I might have executed the technique incorrectly.
 

MrChips

Joined Oct 2, 2009
30,488
Interestingly, the solder takes an unusually long time to melt, despite the iron being heated to 360 Degrees Celsius. Moreover, instead of adhering to the iron's tip as I'd expect, the molten solder forms small balls that drop onto the silicone mat on my worktable.
Can you find a small length of 63/37 Sn/Pb solder from a different supplier to try out. Kester is a well known and reliable brand.
 

Externet

Joined Nov 29, 2005
2,182
Hi there.
I bough them from aliexpress here is the photo
I strongly suspect it should be that chinese solder from Aliexpress. PLEASE super clean your tip and try a well known solder like Kester 44 and come back with findings. It is expensive but buy a small quantity for confirming. Thanks.
 

bassbindevil

Joined Jan 23, 2014
818
Yes, solder will not "wet" a dirty tip, but if it's hot enough it will melt and drip. It's possible you have the temperature much too high, since the calibration of no-name soldering irons can be inaccurate. On mine, I just treat it as an arbitrary number and keep it at a setting that works. And for tip cleaning, I just dip the tip into the brass scrubber, or a water-dampened sponge (or cloth or paper towel) if that's what is available. I don't normally have to resort to aggressive cleaning, since rosin-core solder usually does a good enough job of restoring the tinning. There are "tip cleaning" or "tip tinner" pastes sold in little metal cans. You poke the hot tip in and it sizzles and the tip comes out cleaner and tinned, unsurprisingly. Not essential; I only used it because there was some lying around, probably Multicore tip tinner and cleaner.

Maybe a "magic eraser" would be safe to use if the oxidation doesn't come off. I've never tried that myself, but this guy says it works:
http://www.diytube.com/phpBB2/viewtopic.php?f=3&t=6397
 

SamR

Joined Mar 19, 2019
5,019
This stuff does a pretty good job of retinning a burnt tip but best not to get to that point. An adjustable temp soldering iron, brass coiled metal sponge tip cleaner, and quality solder and flux help. That along with proper tip maintenance as you are soldering by actually USING the brass sponge after each soldered joint before placing the iron back on its rest. Always clean (and resolder if necessary) the tip before turning the iron off to prevent it oxidizing while unused. Hot bare solder free iron tips oxidize fast.
1689740201261.png
 

Ian0

Joined Aug 7, 2020
9,503
The solder will be lead-free because it is cheaper. And the quality of the tip may not be great. And the brass sponge might just be copper-plated steel or something; check if it's magnetic or not. I've found real brass sponges at the supermarket.
Lead free solder is much more expensive that leaded. That's because it is mainly tin, which is ten times the price of lead.
Tin = US$28000/tonne
Lead = US$2113/tonne
The better ones also contain 3% silver.
 

jiggermole

Joined Jul 29, 2016
161
After you figure out what's not right with you're temp and solder composition, I've had excellent success with restoring a tip using SalAmmoniac. From Amazon . Little time, heat, and you'll start to see the oxides come off, tin the tip with good solder after its clean and most of the time you can get the tip back. Its just about the last step I use before ordering a new tip. I have a communal soldering iron at work and my co-workers aren't very good about taking care of tips.
 

bassbindevil

Joined Jan 23, 2014
818
Oh, I stand corrected about the crappy solder being lead-free. Maybe it has too much lead, and recycled lead at that? I bought some "Kaina" on ebay that claimed to be 63-37, but it doesn't behave like the Kester solders. According to comments on this video, there's fake Kaina solder.
 
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