Under what circumstances do the chemicals in matches react?
January 28, 2015 2:18 PM   Subscribe

I lit a match yesterday. I am afraid that the matchbox and everything the match touched will spontaneously ignite. Please reassure me with science, or, failing that, tell me what to do to avoid spontaneous ignition. Thank you very much!

From what I have read, safety matches work by reacting the potassium perchlorate (box states that perchlorate is present) on the match with the red phosphorus on the striker, using friction between the glass embedded in both to generate the necessary heat to convert the red phosphorus to white phosphorus and start the reaction, fueled by the sulfur also present in the match.

What I have not been able to figure out is whether other sources of heat or friction could initiate this reaction, or another hazardous reaction, once the two combine. If a match is unsuccessfully struck against a striker, is it possible for perchlorate residue left on the striker to later react with the phosphorus under conditions other than a match being struck? Could a fully extinguished match reignite itself? If you run a used match under the bathroom tap, could any of the match's components react in a flame producing manner with other residues, such as mineral scale or toothpaste, later on? If water from rinsing a used match were to come into contact with fabric, would the fabric ignite upon laundering? If the answer to any of these questions is yes, what should be done to prevent fire if these things occur?

Thanks muchly in advance!
posted by anonymous to Home & Garden (14 answers total) 1 user marked this as a favorite
 
There are 'Safety Matches' and 'Strike Anywhere' (for camping etc.) matches.
Make sure you are using the former.
See: https://en.wikipedia.org/wiki/Match#The_safety_match
posted by lungtaworld at 2:25 PM on January 28, 2015 [1 favorite]


I have been using the latter for years with no problems.
posted by lungtaworld at 2:28 PM on January 28, 2015 [1 favorite]


As far as I can tell, the answer to all of those questions is no.

What I have not been able to figure out is whether other sources of heat or friction could initiate this reaction...

They kind of could start the reaction, but the reaction wouldn't be sustainable. The phosphorous needs more oxygen than is naturally present in the air, and so there is oxidizing agents in the match head, that provides the oxygen necessary to start the reaction.

...once the two combine

If by "the two" you mean the sulfur and the phosphorous, then no. Because once the reaction between the two kicks off, they burn, and there will be no more burning coming from those two. If you're talking about the two phosphorouses combining, then we're back at the lack of oxygen problem above.

would the fabric ignite upon laundering?

Just a little googling around, it looks like you'd have to heat a match up to about 450 degrees f (230 c) to make it combust. That's pretty close to the temperature at which paper would start to burn (according to Fahrenheit 451), and much higher than, say, the temperatures in your dryer, or pretty much anything else your clothes would encounter.

Matches have been safely used for almost 200 years. I'd guess that you're far more likely at risk from fire from lightning or arson or something than you are at risk from matches and match residue.
posted by DGStieber at 2:36 PM on January 28, 2015 [1 favorite]


Your fears are totally reasonable. The history of matches is just one hilariously awful idea after another, ranging from matches containing bulbs of sulfuric acid, to matches that would spontaneously light in their boxes if jostled, to matches that would produce big glowing abscesses in the matchmakers' jaws. It's only in the last 150 years or so that we've had reliable, safe matches.

For safety matches, most of your questions are answered by dilution. The reaction doesn't proceed without a fairly high concentration of both the phosphorous and the perchlorate, plus a decent amount of friction. So there's no danger of contaminating other things with the fire-making power of the match.
posted by d. z. wang at 2:38 PM on January 28, 2015 [1 favorite]


You cannot re-light a match that has already been lit and left to extinguish under any normal conditions. I have tried. Ever been in a two candle/one match situation? I have. Match goes out, will not re-light no matter how much I want it to. Sticks of spaghetti are more combustible than them (and, if you're in the one match 2 candles situation, is actually the best solution). I have held spent matchsticks in a flame using pliers and they do not re-light. Crumple and wilt? Yes. Light back on fire again? No. Try it yourself. It jut doesn't happen.

I also compulsively grab freebie matches wherever I go and then pretty much never use them, so they spend a lot of time getting smushed and destroyed at the bottom of my bag. I have had packs of matches get so busted around and abused in my book bag that there's no igniter left on the tips any more so they won't light at all. No book bag has ever caught on fire.

Really the only risk from matches is disposing of them while they're still very hot or actively on fire. Always make sure that a match is completely stamped out and/or damp before disposing of it, especially if you're tossing it into a garbage bin. That is bad.

But otherwise there is no way for a match to magically imbue anything else it touches with some sort of combustibile nature. It just doesn't happen.
posted by phunniemee at 2:39 PM on January 28, 2015 [1 favorite]


You cannot re-light a match that has already been lit and left to extinguish under any normal conditions. I have tried.

Really? I do this all. the. time. And these are those shitty green-tipped matches that don't want to light in the first place. So I'm too lazy to try again, and instead just use one of the used matches in the spoon rest and light it in the burner that's already on.
posted by fiercecupcake at 2:57 PM on January 28, 2015


And these are those shitty green-tipped matches that don't want to light in the first place.

The green-tipped matches are strike anywhere matches, not safety matches.
posted by brainmouse at 3:09 PM on January 28, 2015 [1 favorite]


I've been striking twelve or fifteen matches a day on an box full of the other matches, which I don't usually bother to close, for like three years. Nothing's ever blown up, if that helps.
posted by mibo at 3:32 PM on January 28, 2015


Anecdote:

About a year ago, I taught an experiential class on winter survival skills that used strike anywhere matches. We gave these matches to ~500 children (ages 9 and up) over the course of a season. This meant that countless people probably went home with match residue on themselves and on their clothing. I constantly went home with match residue on myself, my clothes, and little bits of lit/unlit matches in my pockets and pack. I still find match heads in my pack occasionally. (not recommended)

Instructors would carry around the unlit matches in an empty pill bottle, since the match boxes would get soggy and useless. No matches would ignite in the pill bottle, even though they were jostling around in there. We would teach students at least 2 ways to light matches 1)on a cast iron pan/a rock/something rough 2)against another match. They weren't given a matchbook to strike on. So it is possible for strike anywhere matches to ignite just off each other

No children burned any matches that weren't near their firepit. Zero reports of people taking some home in their pockets and igniting themselves or their family's washer/dryer. Maybe they were just ultrasneaky/smart/part ninja.

A coworker had several strike anywhere matches in his pockets. They rubbed against each other/his pockets and burned the top of his thigh and melted a hole in his snow pants. I carried matches in my pockets occasionally, though usually singly. I never burned anything I wasn't intending to. I never heard of anyone blowing up a dryer because of unlit/half-burnt/really damn burnt Winter Survival matches in their pockets. 15/20 instructors used the same cranky dorm dryer, we would know if something exploded.

Long-and-short of it: keep 'em dry. Store them in something that won't melt your pocket. Better take them out of your pocket before drying in a tumble dryer just to be safe. You and your clothes are probably ok.
posted by Guess What at 4:02 PM on January 28, 2015


This is one of those things that you would know about if it happened with any regularity. The way product recalls and liability lawsuits are, if matches spontaneously ignited, they would not be on the market.
posted by empath at 5:33 PM on January 28, 2015


Brainmouse, there are green ones that are strike on box and ones that strike anywhere — the latter have white tips like the red ones. I just checked because I was curious. The "green" is because the wood is supposedly sustainable sourced.

Nthing everyone else in not having to worry about the other matches - they take a specific couple conditions to light and while they do burn hot for half a second, the rest of the time they're no hotter than any other small burning piece of wood (which is to say, pretty hot).
posted by BlackLeotardFront at 11:27 PM on January 28, 2015 [1 favorite]


Here's the thing: the entire "payload" of oxidizing chemical at the end of the match is required for the active reaction of the generated white phosphorous from reasonably vigorous friction to initiate a chain reaction of sufficient energy to set one very small stick of very dry wood on fire. The minuscule residue a strike would leave on the striker surface is not going to set anything on fire.

All of the chemicals in the match are going to be fully oxidized by combustion: within a fraction of a second of striking that match is basically no more burnable than any small stick of wood and nothing is going to make it catch on fire that wouldn't start a fire anyway. None of the scenarios about running the match under the tap you posited make any sense chemically. When a drop of water containing a profoundly diluted amount of fully oxidized matchhead chemicals dries on your pants that... Well that's just crazy talk basically. This is about anxiety, not combustion chemistry.
posted by nanojath at 11:46 PM on January 28, 2015


Here's my (slightly less reassuring) anecdote: I once picked up a book of matches of the kind they give away at restaurants from the dash of my car. The car had been parked in the sun on a hot summer day, the dash was black, the matches were cheap. The whole pack went up in my hand. No match had made any contact with the striking surface; I suppose that two of them rubbed together as I scooped them up. It looked like a really bad burn, bits of match head were stuck between my fingers and it got really blistery. I did go to emergency, but within a week it was totally healed. So, I say yes, perhaps under certain circumstances, a match pack can rapidly combust without you striking a match.
posted by alltomorrowsparties at 1:17 AM on January 29, 2015


This is a derail, but yeah, what BlackLeotardFront said. The green ones are supposed to be sustainably harvested wood. I don't know what's wrong with that wood, but they break 2 out of 3 times I try to light them...so I'm pretty sure I'm just using MORE wood instead of less.
posted by fiercecupcake at 7:22 AM on January 29, 2015


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