Here is a thing that happens constantly, and that almost nobody diagnoses correctly.
Someone buys a decent temperature-controlled iron. It works beautifully for two weeks. Then it starts to feel sluggish. Joints take longer. They turn the temperature up, which helps briefly and then makes it worse. Within a month the iron is barely usable, and they conclude they bought a bad one.
They did not. They killed the tip, and it took about two weeks of small neglect to do it.
This lesson is the shortest practical habit in the whole course. It takes five seconds, you do it a handful of times per session, and it is the difference between an iron that lasts years and one that disappoints you by Christmas.
By the end of this lesson you will be able to tin a tip correctly, understand why a bare tip physically cannot do its job, recognize a tip that is dying, and revive one that has gone too far.
6.1 What "tinning" means
The aim of this section is to define the thing, because the word sounds like jargon and describes something very simple.
Tinning is coating the working end of your tip in a thin film of fresh solder.
That is all. You melt a little solder onto the tip so that the metal is covered rather than bare. A properly tinned tip looks bright and wet, like a drop of mercury clinging to the end.
You tin at three moments, and they are easy to remember:
- When the iron first reaches temperature, before you do anything else.
- Between joints, as part of the wipe-and-tin routine in section 6.3.
- Before you switch off, leaving a generous coat on it for storage. This one is the most often skipped and the most important.
That is the entire practice. What follows is why it matters, which is worth knowing because knowing it is what makes you actually do it.
6.2 Why a bare tip cannot do its job
The aim of this section is the heat-transfer reason, which almost no beginner is ever told and which explains the sluggishness described at the top of this page.
There are two reasons to keep a tip tinned. The famous one is protection. The one that matters on your very first joint is geometry.
Reason one: contact area
Section 1.6 introduced this and it is worth restating precisely.
A component leg is round. A tip face is flat or angled. Press one against the other and, in strict geometry, they touch along something very close to a line, or with a conical tip, a point. Heat has to cross that tiny interface, and heat crosses a tiny interface slowly.
A tinned tip changes the geometry completely. The film of molten solder flows into the gap. It fills the space between the tip and the leg, and between the tip and the pad, and suddenly you have a broad, continuous bridge of liquid metal instead of a line of contact. Heat pours across it.
The difference is not subtle. A tinned tip brings a joint up to temperature in about a second. A dry one can take five, if it gets there at all, and during those five seconds you are cooking the component and hunting for more heat.
Solder on the tip is not solder for the joint. It is a bridge for heat.
That distinction is the whole of Section 1.6: a film carries heat, a payload is the mistake. They look similar and they are opposites.
Reason two: oxidation
The long-term reason. Hot metal in air oxidizes, and a soldering tip is very hot metal in air for hours at a time.
Tips are iron-plated for exactly this reason, but the plating only survives if it is protected. Left bare and hot, the working surface oxidizes to a dull gray or black crust. That crust is chemically not the metal underneath, and solder will not wet it, which is the same problem the pads have in Lesson 3.
A film of solder is a physical seal. Where the solder is, the air is not, and the tip underneath is preserved.
Figure 6.1: A dry tip meets a round leg at almost a line. A tinned tip flows into the gap and bridges to the leg and the pad at once.
6.3 The routine
The aim of this section is to give you the actual physical habit, in order, so it becomes automatic.
Between joints, and any time the tip looks dull rather than bright:
Wipe, then tin. Always in that order, and never wipe and walk away.
- Wipe the tip on brass wool or a damp sponge to take off the spent flux residue and old dull solder. Two or three quick passes.
- Immediately touch fresh solder to it, just enough to coat the working face. It should go bright and wet.
- Go and make your joint, or put the iron back in the stand.
The mistake is stopping after step one. A freshly wiped tip is a bare tip, which is the worst possible state to leave it in: clean, hot, and completely exposed to air. It will start oxidizing within seconds. Wiping without re-tinning is not tip care, it is tip damage with a tidy appearance.
Brass wool or sponge
Lesson 4 covered the buying decision. The practical difference:
- Brass wool scrapes the residue off mechanically and does not cool the tip, so the iron is ready immediately and there is no thermal shock.
- A damp sponge works, but pressing 350 °C metal into cold water shocks the tip every time and drops its temperature, so you wait for recovery. If you use one, damp, not wet: squeeze it out until it is barely moist.
Before you switch off
This is the one to build into muscle memory. Leave a deliberately generous blob of solder on the tip before powering down.
Not a thin film, an obvious coat. It will be there protecting the metal all the way through cooling, which is when a tip is most vulnerable, and it will still be there next time. You simply wipe it off and re-tin when you start.
A tip stored bare will oxidize gently between sessions. A tip stored under solder will not.
Figure 6.2: Wipe, then tin, in that order. A freshly wiped tip is a bare tip, and leaving it that way is the fastest way to ruin one.
6.4 How tips actually die
The aim of this section is to name the four causes, because three of them are choices you can stop making today.
1. Running too hot
The single biggest killer. Oxidation accelerates sharply with temperature, and every extra degree costs tip life.
Most through-hole work is comfortable at 300 to 350 °C. There is rarely a good reason to sit above 380 °C, and doing so routinely will visibly shorten a tip's life.
Here is the trap, and it is a vicious circle worth recognizing: your tip starts to oxidize, so heat transfers less well, so joints feel slow, so you turn the temperature up, which accelerates the oxidation, which makes it slower still. People take a tip from new to dead inside a month this way, and every step feels like the sensible response to the previous one.
If your iron feels sluggish, clean and re-tin the tip before you touch the temperature dial.
2. Being left on, bare, doing nothing
Idle time at temperature is where most oxidation happens, because nothing is being wiped or re-tinned. An iron sitting in its stand for twenty minutes while you read the instructions is quietly cooking its own tip.
Tin it before you put it down, and use the automatic power-off that Lesson 2 recommended.
3. Mechanical abuse
The plating is thin. Things that go through it:
- ⛔ Filing or sanding the tip. Never. This removes the plating permanently and turns a repairable tip into scrap. If a guide tells you to file a tip, it is describing an unplated copper tip from decades ago.
- ⛔ Scraping it with a blade to remove crust.
- ⛔ Using it as a lever to push a stubborn component.
- Aggressive scrubbing on very coarse wire wool. Brass wool is soft on purpose.
4. The wrong flux
Water-soluble and aggressively activated fluxes attack the tip if residue is left on it. Lesson 3 recommended rosin cored or no-clean, and this is one of the reasons.
6.5 Reviving a tip that has gone
The aim of this section is to save a tip you have written off, because it usually can be saved.
The symptom: solder will not stick to the tip at all. You touch solder to it and the solder balls up and rolls off, or clings in a lump on one side while the rest stays dull gray or black.
That is oxidation. The metal is fine underneath.
The ladder, in order
1. Wipe hot, tin immediately, repeat. Sometimes all it needs. Wipe firmly on brass wool, immediately load fresh solder, wipe, immediately load again. Three or four cycles. Fresh flux from the solder is doing the chemistry.
2. Drown it in flux. Turn the temperature down a little, coat the tip in flux paste or from a flux pen, and work fresh solder into it while wiping. Flux is designed to strip oxide, and this is a concentrated version of what it does on a pad.
3. Tip tinner. A small tin of active chemical tinning compound, which Lesson 4 mentioned: an aggressive flux mixed with fine tin powder. Push the hot tip into it and swirl.
⚠️ It works chemically, not by scrubbing. The flux reduces the oxide and the tin powder wets straight onto the metal underneath as it is exposed. That distinction matters here more than it might elsewhere, because the next paragraph tells you never to abrade a tip, and it would be easy to assume this stuff is a permitted way of doing exactly that. It is not. It is the opposite: a chemical route that removes the oxide without touching the plating.
It is the intended tool for this job, it is cheap, and it revives tips that look genuinely dead. Wipe and re-tin properly afterwards.
4. Accept it. If the plating has actually been breached, by filing, scraping, or long neglect, the tip will pit and no longer hold solder in that spot. That one is over. Tips are consumables, and this is why Lesson 2 said to check that replacements are cheap and easy to get before you buy an iron.
⛔ What not to do at any point in that ladder: file it, sand it, or scrape it with anything metal. You will convert a recoverable tip into a permanently dead one, and it is the most common piece of bad advice on this subject.
Figure 6.3: A healthy tip is bright and wet. A dying one is dull and patchy. A dead one is gray or black and solder rolls off it.
6.6 A sensible working temperature
The aim of this section is to settle a number, because "it depends" is not usable advice for someone standing at a bench.
Start at 320 °C and change it only for a reason.
- Leaded solder melts at 183 °C, so 300 to 320 °C is plenty.
- Lead-free melts around 217 to 221 °C, so 330 to 350 °C is more comfortable.
- A large pad, a ground plane or a thick wire may want 370 °C briefly. Lesson 7 explains why some pads drink heat and what to do about it.
- ⛔ Above 380 °C routinely and you are trading tip life for nothing. If you need that all the time, the real problem is thermal recovery or tip size, not temperature. That is Lesson 2.
Hotter does not make solder flow better once you are comfortably above its melting point. It makes the flux burn off faster, which makes flow worse, while damaging the tip and risking the component. This is one of the least intuitive things in soldering, and it catches nearly everyone.
What this sets up
Lesson 7, reading the board, explains why some joints on a real board will fight you even with a perfectly tinned tip at a sensible temperature.
Lesson 8, your first joint, is where the tinned tip earns its keep.
Lesson 9, good joint bad joint, includes the faults that come specifically from a poor tip, so you can trace an ugly joint back to its cause.
Frequently asked questions
How do you tin a soldering iron tip? Bring it to temperature, wipe it on brass wool or a damp sponge, and immediately melt a little solder onto the working face so it looks bright and wet. Do it when you start, between joints, and generously before you switch off.
Why won't solder stick to my soldering iron tip? It has oxidized. Try wiping and re-tinning several times in quick succession, then flux, then tip tinner. Do not file or sand it, which destroys the plating permanently.
Should I use brass wool or a sponge? Brass wool is better: it removes residue without cooling the tip or thermally shocking it. A damp sponge works, and should be damp rather than wet.
What temperature should I set my soldering iron to? Start at 320 °C. Around 300 to 320 °C suits leaded solder and 330 to 350 °C suits lead-free. Avoid sitting above 380 °C, which shortens tip life without helping.
Why does my iron seem to have gotten worse over time? Almost certainly an oxidized tip. Clean and re-tin it before you touch the temperature. Turning the heat up is the intuitive response and it accelerates the problem.
Should I leave solder on the tip when I turn the iron off? Yes, deliberately and generously. The coating protects the tip through cooling and storage. Wipe it off and re-tin when you next start.
Can I file or sand a soldering iron tip? No. Modern tips are iron-plated and filing removes the plating, which cannot be replaced. Advice to file a tip refers to bare copper tips from decades ago.
Next
Lesson 7: Reading the board, and working in the right order. Silkscreen, polarity, the assembly order that stops parts falling out, and why some pads drink heat far faster than others.
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