What is tinning and why is it important?
Tinning a soldering iron or rather the tip is something you should get into the habit of doing regularly. If you keep your soldering iron tip tinned it will last longer and be better at soldering as it will conduct heat better.
What are soldering iron tips made of?
Soldering iron tips are predominantly made of copper. This is because copper is excellent at conducting heat and that's exactly what we want it to do. Unfortunately if they were just made of copper they would very quickly dissolve with the application of solder. To stop this happening they are iron plated. This is only a thin layer though and you need to be careful when using anything even mildly abrasive when cleaning the tip.
If a tip oxidises or burnt flux accumulates it won't be able to solder properly cleaning the tip frequently will also prevent the build up of harder to clear deposits that can become burnt on. A dirty tip wont “tin” very easily and hence won’t solder very well either so I think we are all agreed its best to keep your tip clean.
How to clean a soldering iron tip
- Tinning a soldering iron should be done when the tip is clean. The traditional method of keeping a soldering iron tip clean while using it was to dab it onto a wet sponge. This was usually integrated into the soldering irons stand and was the mainstay for years. Apart from cleaning the flux off, it was also good at cleaning off surplus solder however there is now a new and in my opinion better method and that’s the soft metal shavings pot. These cleaners avoid the cooling effect that dabbing the tip onto a wet sponge creates. This thermal shock is avoided by using the dry method and prolongs the tips life, always a good thing.
Tinning the tip
- To tin you simply apply some new solder to the newly cleaned tip, the rosin in the solder will flux to enable the solder to take to the tip leaving it bright and silver coloured. When you have finished soldering apply a little solder to the tip and then turn the soldering iron off.
How to use tip tinner
- If the tip is getting too dirty to tin with this method you can purchase various tip tinners and cleaning pastes, this is usually a much stronger flux that will clean and tin a tip. To use it you just dab your soldering iron tip into it. You should then find it will tin much easier.
- There are also special polishing bars if the tip is particularly dirty or badly corroded. Weller makes a particularly useful one. You need to be careful though with anything that is too abrasive as you can remove the plating that is put on the copper tips. Copper is used because it’s excellent at conducting heat but it has a harder wearing plating and if that is removed the bare copper of the tip quickly dissolves and you will get holes and a badly performing tip. Sometime you just have to get a new one. When a tip has been cleaned using a paste or bar it’s important to tin it straight away so as to not leave the newly exposed metal to oxidise.
Sal ammoniac tinning block
If a soldering iron tip is particularly black and dirty it can sometimes be bought to life by using a sal ammoniac tinning block. This should only be done in a well ventilated area because of the fumes it gives off. Basically you just gently rub and rotate the hot soldering iron tip in the block. It will start to smoke and melt into the block and at this point you should introduce solder to the tip. This should take to the tip much better given the addition of the sal ammoniac and you will have a shinny looking tip again.