Do You Need A Solder Fume Extractor?

We’ll admit it. Most of us have been soldering since we were kids and we don’t think of it as a particularly dangerous activity. Just keep the hot and cold end of the iron straight and remember not to flick solder off the tip on your leg and you are fine. We sometimes roll our eyes a bit at the people with the soldering fume extractors unless you are soldering 8 hours a day, although we’ve occasionally used a small fan nearby just to get some circulation. [Tanner Tech’s] video on soldering fumes might make us rethink that, though (see below).

[Tanner] rigs up a fan with some plastic bottles, fans, and some cotton balls. But that didn’t do very much. Instead, he replaced his fan assembly with a shop vac. Then he examined what was on the cotton balls.

Realistically, the cotton balls probably got nearly all the fumes from the things he soldered. In real life, your lungs would get only a small percentage of that. Still, the cotton balls and even the housing were full of flux residue and fumes. The cotton was very sticky and coated with a yellow substance. and a white powder.

You can imagine your lungs getting even a little of the gunk that was on the cotton balls. It would be interesting to do some analysis to determine what all that residue was.

If you want to build your own extractor, unsurprisingly we’ve seen it done many times. We’ve also talked about general safety measures you ought to be taking before.

78 thoughts on “Do You Need A Solder Fume Extractor?

      1. Egg on my face, Yann… I thought 60/40 tin/lead melted at a lower temp than 70/30. The stuff I are fergitt’n !!!

        Still, while I never mined the aroma a lot, I somehow knew, too much of ANY smoke was a foul thing. And I are not nor weren’t never a very aroma squeemish person. In fact, helping a mech so my pickup axle, I embraced one ancient smell of my youth, differential lube. And 100 feet away, I like skunk… an ingrediant equal to ambergrish, (sp? of which I ain’t never had the pleasure? whale vomit?) in the best perfumes, or it once’t was so.

        Leave us to enjoy ham ‘n beans and apple pie, and let nanites enjoy the sweet fog of rosins. As I prep to braze a drain plug onto a pickup differential, I considered the borax fumes. Ain’t never had much memorable sperience with it, dad having needed it so rarely. I saw him silver solder a cast iron trivet, but recall the aroma, if any, not. Smell is supposedly a very strong memory key. I concur; it can be so. It has prodded a strong urge to locate the memory it has evoked. Ahh… wood-burning sets! ????????

          1. There are hand wipes like hygenall that have citric acid and some proprietary chelation / buffers in them. Citric acid solution on its own probably does a decent job. Shower cleaners have EDTA in them that will help a little bit only for oxidized lead, which is probably where the citric acid comes in, as it’s an acid and chelator.

        1. Back in the 1980s I worked for a small company that ran a small assembly line. There were about 10 or so hourly workers in the back soldering PCBs by hand. I went back there one time and saw one of them holding a component with one hand, the iron with her other hand and the solder in her mouth. I told her she couldn’t do that and she got mad at me.

          1. I know some very senior Silicon Valley guys who have always done that. Solder or more components. Whichever worked better at the moment. Anyone panicking here who ever used lead weights for fishing? Or wheel balancing? Or glass work? Or…..

          2. “…Anyone panicking here who ever used lead weights for fishing? Or wheel balancing? Or glass work? Or…..”
            …or drove a car, or was driven in a car, prior to the mid 1980s (TEL in your petrol).. or drank water from a house built before the 1980s (leaded drinking water pipes… still very much in evidence till this day).
            Lead is all around you, but the amount you get from soldering, is pretty small beer. Don’t lick the stuff, don’t deliberately sniff the fumes (and don’t melt down old car batteries.. but that’s a story for another day)…

        2. Metallic lead is not a big deal, it is not bio available and it will generally pass through. It is the bio-available forms of lead like chlorides that are of most concern. Same thing for mercury, merallic mercury has a biological half life of about 15 days, it will pass through, it is the organic mercury compounds that are the real killer.

      1. After using lead solder and no fume extractor for years, I got my blood tested. No significant lead exposure at all. You should probably worry more about your drinking water.

    1. I started soldering stuff when I was about 8. I am now 80 and still can’t break the habit.
      I started getting the occasional nose bleed a couple of years ago and thought is was dryness in the house. More recently I looked up rosin core flux and found that, yes, even rosin core flux has some constituents that make Hydrochloric acid when heated. I then realized that, now that I am older and wear a magnifying visor and get close to my work, I am breathing in some of that hot flux. Looking back, I could easily relate the nosebleed to time putting circuits together at the bench. I added a little fan to suck away the fumes and also pay more attention to the smoke and, NO more nosebleeds.

    1. As a group, the folks with the highest level of radiation exposure, including workers in all of the nuclear industries, coal miners, flight crews, etc?


      By a lot.

      Of course, there are a limited number of cases where nuclear workers, patients, or the idiotic have gotten fatal exposures, it is a tiny number when compared to smoking induced lung cancer deaths. Take out the former Soviet Union and I think it’s under 20. Maybe <10 if you take out the folks who tried to scavenge a radiation source from an unoccupied medical facility in South America a while back.

      1. In terms of nuclear radiation, not really. Yes tobacco accumulates polonium and lead isotopes, but the level of radiation these kick out is tiny. Yes you’re breathing them in which makes the tiny level of radiation they emit far worse (our skin does a great job of stopping alpha and beta) but is still negligible. The real dangers of smoking are the damage high energy smoke particles do to cells. Everything you consume contains at least some radioactive atoms, our testing has just become so sensitive we can detect minute amounts far below dangerous levels.

        People tend to latch on to single things like radiation or “toxic chemicals” as the only dangers, forgetting that its the dose that makes the poison, and we’re all subjected to radiation and toxic compounds on a daily basis.

        1. Polonium is a strong alpha emitter. It is not a good thing to introduce it regular in to your lungs, the place where alpha radiation will do the most possible damage.
          I have already heard, that this accounts for a significant amount of the tobacco smoke related lung cancers. The rest is from the toxic chemicals. Anyway, smoking causes about 90% of the cases of lung cancer.

      2. No kidding… depends on the radiation emitted and the element or molecule. Think of how potassium flows through the body versus cesium or strontium… then in the natural or non-natural radioactive isotope forms.

        I sometimes wonder if cigarettes and other diets are used in tracking. Add in flourine and maybe some other more main stream now consumer over the counter entities and there are some interesting tracking options for remote sensing.

    1. Lead doesn’t vaporise during soldering; a little may get on your skin while handling solder and then ingested when you lick your fingers. Washing reduces that. Even the lead-free regulations are more about reducing the amount of lead in e-waste than reducing the risk to manufacturing workers.

      Fluxes on the other hand can be fairly nasty organic acids and you should avoid breathing the fumes if at all possible. Working in a well ventilated area does a lot to mitigate that issue too, even if you don’t explicitly use an extractor fan.

      1. Ironically lead-free flux is generally a lot more aggressive, because lead-free solder has more trouble wicking to begin with. So the lead-free solder is probably a lot more dangerous to the average hobbyist.

  1. I don’t think the lead is the problem with the fumes, but those from the flux are.
    Although it is not proven as the cause, I have been soldering both hobbyist and professionally for many years and now have a lung condition. Some of the doctors do not believe me when I tell them I am a non-smoker.
    Finally, I made this..
    Many years too late for me.
    Even if there is just a chance the fumes may cause damage, it is worth while at least having a fan to blow them aside. It is a bit foolish to say the fumes are not dangerous so don’t worry when it is so easy to limit the exposure.
    Added safety measures I did insist on with my PCB assemblers and students were to wash thoroughly after soldering and no eating while soldering, and to always wear safety specs. In my years I have only had a couple of occasions with a splash of solder across my glasses, both times while unsoldering a wire that sprung back and launched molten solder. But it only needs one time,.

    1. Colophony lung is a well recognised occupational lung disorder arising in those who develop hypersensitivity to the rosin in the solder.

      Similarly, there are plenty of case reports of occupational asthma arising in workers burning or melting off the insulation on wires prior to soldering, which can, with some coatings, i.e. polyurethane based, liberate isocyanates which will cause hypersensitivity in predisposed people over time.

      N-Methyl-2-pyrrolidone is also used as a flux in surface mount solder, and is another potential exposure issue with heating and volatilisation.

      Others have correctly pointed out that the higher temperatures of lead free solders have the potential to create more of a pea soup of thermal degradation products from the fluxes used.

      Popcorn lung is worth googling for those keen on vaping flavoured things, incidentally.

      1. I’m sensitive to colphony fumes since my teens. It sucks. Fortunately, simple disposable filtering mask works, I’ve even used a dish towel few times as a makeshift mask. The most stupind thing I can do is to tell myself “it’s only one wire, no need for a mask”. It’s never just one wire. It is one wire and then the other and then redo and then… hours of coughing lungs inside out.

    2. I accidently flicked molten solder into my eye once. The eye doctor noted that she usually needed to use yellow dye to see cornea damage, but mine was visible without it. No worries, I had blurred vision for a couple days but it completely healed up swiftly.

    3. I flicked molten solder in my eye once. The eye doctor was impressed that she could see the damage without yellow dye eyedrops. No worries, my vision was blurry for a couple days but swiftly healed on its own.

      1. Walter Midgely, who developed leaded petrol (gasoline), and then CFC’s, for which he won the Society of Chemical Industry’s Perkin Medal for this research in 1937, had a fusible plug on a boiler spray fine particles of metal into his eye which were too small to pick out individually.

        His solution: he dissolved the metal out using an eyecup and mercury.

        I’m not sure this cavalier attitude to safety would be rewarded today, unless, of course, the US EPA found itself without a head again…..

      2. Interesting bit of info! A quick web search brought up this link.
        Of course the article left me imagining a cartoon wherein the mans eye just takes in a blob of the mercury and he ends up waling around with one “googly eye” from the mercury in it.

  2. IF you follow best practice then the amount of lead exposure is insignificant below an iron temp of 380 C (716 F). It starts getting significant above 450 C (842 F). That said, it’s not a step function but a log curve that describes the vapor pressure.

    All the studies I’ve found assume “best practice” is being followed. I have to admit I don’t always follow best practice.

  3. Vapour pressure of lead at 350 C is about 2.2E-8 mbar which equates to release of 1 atom per square centimeter per minute. People building ultra-high vacuum equipment do not use lead solder because its vapor pressure is too high, but I doubt it is a problem for the rest of us.

    1. Even then you can get away with generic lead solder in UHV for most normal sized wire connections, like on a connector or something. It is the left over flux that is the big issue when having soldered joints in the system.

  4. Put your lips nearly together and blow. Unless this is constant full board work you can time shots of soldering with a steady fine blow. Then breathe in clean air. The most gentle of a fan breeze is enough till a hood or space vented outside is required.

      1. Back in the ’80’s my Op Amp instructor told us of the fellow who reached between the 5 volt bus bars on a large mainframe (well, all mainframes were large back then). His wedding ring shorted the power supply, which in turn vaporized the wedding ring. Fortunately (?) the arc cauterized the stump of his finger minimizing bleeding.

  5. Early in my working life I used to solder pretty much all day doing faultfinding and repair, leaning in over the work and getting a faceful of everything with no extractors whatever. Did that for five years and developed chronic sinusitis that took ten years to fully clear. Your lungs aren’t the only thing you should worry about.

  6. Hmmm… when I solder I always make a habit of it to inhale while not above the smoking iron and exhale during soldering. (gently blowing the smoke away (if it obscures my view) at the same time). Why would I want to inhale the smoke directly from the iron (just like the cotton fume extractor does) that makes no sense. Who is soldering over his/hers lungs?

    This test is interesting… and although safety is important, don’t get me wrong, I just wouldn’t compare the act of soldering to the act of smoking.

  7. I honestly still struggle with the fact that people have such a negative attitude about soldering with lead free solder. I have been saying for years: if you think lead-free is difficult, then you are not using the correct equipment. When I switch between tin/lead and lead-free with my Ersa I-Con station or older Metcal SP200, the ONLY things I change are the tip to avoid cross contamination and the temperature (on the Metcal, the temp is driven by the tip chosen). Other than that, my soldering technique is identical and I haven’t had challenges with lead-free since 2009. I even use the same liquid flux for both, usually Kester NF372-TB. My lead-free solder choice is Kester 275 Flux Cored solder, SAC305 alloy in 0.4mm or 0.8mm diameters.

    1. ” I have been saying for years: if you think lead-free is difficult, then you are not using the correct equipment.”

      Getting my employer to buy “the correct equipment” is another matter all together.

  8. Just a thought – the “control” isn’t fair. The loose cotton balls haven’t been shoved in a bottle and had a shop-vac attached to them to suck the air out. I’d be willing to bet that, even without the soldering, the cotton balls would have meshed together under those conditions and ended up quite different to the “virgin” balls… as it were.

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