New soldering iron smokes from inside the handle (not from tip) - is this a problem?

Question

I've started using a brand new soldering iron for the first time and it's not working as expected:

• After about 10 seconds of power, smoke starts coming out from inside the handle, next to the metal shaft. After 30 seconds on, there's a lot of smoke pouring out, like a candle that's just been extinguished. I've turned it off and on and this still happens
• There's no smoke from the tip, and a very small amount from where the tip attaches to the shaft
• The tip doesn't get hot enough to melt solder after being on for a little over a minute. I haven't tried leaving it on for longer than that because the amount of smoke from inside the handle seems to just keep increasing. The handle doesn't seem to get noticeably hot in this time

I bought it in a 230V country (UK) and am using it in a 230V country. It's a 40W Maplin soldering kit.

I expected the tip to smoke, but not the inside of the handle. Looking this up online, I see a lot of similar questions being mis-read as being harmless tip smoking, and a lot of comments that they're often coated in oils that burn off. It seems to me that these wouldn't be inside the handle, though? Or would they? Some other comments seem to think this is a sign of a defective iron, but don't offer anything to back up this opinion beyond "I've never seen that".

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Just found in the paperwork:

The first time you use the soldering iron, it may smoke slightly and there may be a smell of burning as the heating element dries out. This is normal and should only last a short while

...which sounds unusual and is a little vague. This seems like it'd explain the small amount of smoke where the tip joins the metal shaft, but I'm not sure if this would explain large amounts of smoke from within the handle.

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Update: I tried leaving it plugged in outdoors under supervision (fire extinguisher at the ready). After about 7 minutes it seemed to stop smoking, so I took it back inside (keeping the fire extinguisher handy), let it warm up again for a few minutes, started soldering, then noticed it was smoking again. It stopped smoking pretty quickly after killing the power, and was still hot enough that I could finish my soldering, but I think I'll be looking for a replacement.

Answer 1

Maybe

I bought one of those from Maplin a year or so ago. It produced a lot of acrid smoke the first time I turned it on, and I was also concerned about it. It's a very cheap and nasty product.

I dismantled it insofar as was practical, but couldn't see anything wrong with the wiring, but there was some residue on the hot parts which was burning off. I put it back together, plugged it into a RCBO protected extension lead, and left it turned on sitting on a fireproof mat in the garden for a while. The smoke died away in a few minutes, and the smell was gone after an hour. The iron has been perfectly serviceable ever since.

Now, I haven't seen your iron, so I can't say for sure whether it's the same. Can you safely leave it somewhere for the smoke to die away? Somewhere fireproof, just in case.

Answer 2

Yes this is a problem. Don't inhale the smoke, and return it.

The tip should not really smoke either, except for when you are putting flux on it (a lot of solder will have flux-cores, so solder will make it smoke some too).

Answer 3

It's common for manufactured items to have some trace amount of surface contamination; in particular, metal items may have residues of oil or similar substances. So, a device intended to get hot may smoke a little bit when new until the contamination is burned off.

That said, nothing inside a handle should be getting hot, and even at the tip, there should be no more than a few wisps of smoke.

It sounds like your iron has a poor electrical connection inside the handle, which could be getting hot, even if it isn't noticeable; the smoke would then be coming from burning insulation.

It seems like your iron is defective, should not be used, and should be returned.