the sequence of exothermic chemical reactions between a fuel and an oxidant accompanied by the production of heat and conversion of chemical species

So this is what we’ve been doing for entertainment recently:

My parents have a freestanding fire pit they bought last summer and never used, and so Elana, a sort of Ambassador Eagle Brownie Girl at heart, has been putting it to good use. For several nights running we’ve rustled up wood from the various scrap piles around the yard and gleefully set it ablaze. This has turned out to be quite good for family unity — having something to do, a low-key central activity around which to organize conversation, has led to more thoughtful and less awkward intergenerational talk. I don’t know why, but staring into the fire, you can ruminate on religion and culture and growing up in a way that is less likely in a torchiere-lit living room.

It has occurred to me, sitting there in the flickering dark, that fire-building is one of those important pieces of shit-hits-the-fan, End-of-Days lore that ought to be passed down from parent to child. Let’s be honest — I’m not good for much after the apocalypse. I haven’t been storing food, for example. I can shoot a rifle, but I don’t in fact own a rifle, and man, I suuuuuuuuck with an atl-atl.

But one thing I think I’m actually okay at is tending a fire. Elana, who is really good with fires, likes to tease me about not having done enough camping when I was young, but the basics are pretty simple, and in case this blog turns out to be the only thing to survive the coming catastrophe, I write the following for my son.

Some people will tell you about the “fire triangle.” This is very confusing, because you’re going to think it’s something practical, like, “arrange your sticks in a triangle,” when in fact what people mean is, “you need three things to make fire.” Those three things are heat, fuel, and oxygen. Heat and fuel are obvious; oxygen a little less so. Most of the actual technique in building and maintaining a fire has to do with getting oxygen into the process. More on that in a minute.

Part 1: Make It Hot

Starting a fire is not hard with modern tools. I highly recommend matches or a lighter. If you are actually reading this after the apocalypse, you may have to make do with less. Many metals are pyrophoric, meaning that very fine shavings of them will ignite spontaneously in contact with air. Traditionally a piece of flint was used to nick tiny pieces off of iron or steel; the tiny pieces would ignite as they sailed through the air, and a hot spark would land where you were trying to make a fire. This fellow, who sells specially formulated “firesteel,” demonstrates the process in a wood-clad hallway:

This video, on the other hand, assumes that you have access to soda and chocolate bars and yet for some reason still need to cook over an open fire. I suppose it’s possible. It also assumes you have fairly strong direct sunlight, an assumption that may not hold in certain post-apocalyptic scenarios:

Anyway, if you were smart enough to raid a convenience store for the Royal Crown and the Toblerone, I hope you also picked up matches.

Part Two: Little To Big

Once you’ve lit the match, you’ve got to set something on fire. What should you start with? People throw around a lot of terms for “stuff you set on fire” — they’ll tell you to start with “tinder,” then “kindling,” etc. — but the general principle is little to big. This is related to the oxygen thing — again, more on that later, but basically you want tiny pieces of flammable stuff surrounded by a lot of air. So pine straw burns better, to start with, than pine logs, and crumpled up shreds of newspaper burn faster and easier than a neatly folded sheaf. (Newspaper is something you won’t have in the future, post-apocalyptic or not, but you can’t burn your iBrain, so I don’t really know how to relate to you anyway, but… where the fuck was I?)

So, little to big: start with small bits of dry, flammable material, either crumpled or well-shredded so lots of air can get in. That stuff will burn crazy fast, but that’s okay, because it’s not the main fuel for your fire. You’re just using it to catch the spark of your match/lighter/firesteel/Coke can and transfer that spark to slightly larger fuel: small sticks are good. Then you progress to larger sticks, branches, and finally logs. Little to big.

Part 3: Everything Goes Up

I mentioned earlier that pine straw would burn better than a pine log, because oxygen has an easier time getting into a mound of straw than into a solid piece of wood. Solid wood, of course, only burns on its exterior surface, and so if you want to burn anything bigger than a dried leaf you’re going to have to get the maximum amount of oxygen possible onto that surface. Again, there’s a simple principle to remember here: everything goes up.

Look, fire is hot, right? And the hot gases that make up the visible flames are compelled upward by the comparatively cool and dense air around them. Or maybe it’s that fire, the substance of hell itself, reaches upward toward heaven in longing. I’m not really sure. But the point is that fire tends to go upward — if you hold a burning stick out in front of you, the flames point upward from the top surface of the stick.

So flame moves upward, generally, which means it needs to be replenished from below, and that’s where your oxygen needs to be. You need to get as much oxygen as possible coming up from below the actual flames themselves. This means that anything larger than the initial “tinder” — the shredded/crumpled stuff — needs to be carefully arranged so as to allow air to come in from the bottom. There are probably a number of good ways to do this, but the ones you want to learn are the “teepee” and the “log cabin,” because they will remind you of Indians and Abraham Lincoln, respectively, which will be good when you’re sitting around your post-apocalyptic fire telling your children legends about the great and terrible “America” which once was. You don’t want to leave out the aboriginal peoples — they’ve suffered enough without you slighting them — and of course talking about Abraham Lincoln gives you an opportunity to use the phrase “stovepipe hat,” which would otherwise fall out of use entirely.

Here, then, are the two configurations of sticks you are advised to use. The “teepee” configuration, in which the sticks form a cone and converge to lean against each other at the top, requires a little bit of balance but allows for terrific airflow and lets fire creep upward, as is its natural wont.

The “log cabin,” by contrast, doesn’t require a balancing act — you just lay two sticks on the ground, then lay two sticks across them, then lay two sticks in the original direction again, and so on, as high as you like. You can accommodate more sticks this way, creating a nice blaze all at once. Also, you don’t have to worry about random bits of flaming stick escaping your fire pit as they burn and crumble, which is a concern with the teepee. On the other hand, you do have to worry about looking like a guy who spends way too much time arranging sticks.

Whichever method you choose, the sticks will burn for a while and then collapse into the bottom of your fire pit. You’ll feel an inevitable sense of loss and dismay when this happens, but try to be philosophical about it — the dying sticks are transmuted into living, glowing coals.

Part 4: Bed Of Coals

This is the last thing you need to know, really: after wood burns with a flame, it goes into a second stage of burning as a hot coal. This stage is actually more awesome than the flame stage, not only because of the creeping orange glow, but also because when you’ve got a bed of hot coals going in the bottom of your fire pit, you can essentially keep a fire going indefinitely just by adding more fuel. You may have to arrange this fuel artfully so that, for example, air can still come in from the bottom. But you shouldn’t have to light the fire again — your bed of coals lights each new piece of fuel as it’s added.

And that’s it, really. Enjoy your fire, and if it’s cold where you live, be sure to keep in mind Jack London’s grim warning about survival in the wild:

[A]ll this—the mysterious, far-reaching hair-line trail, the absence of sun from the sky, the tremendous cold, and the strangeness and weirdness of it all—made no impression on the man. It was not because he was long used to it. He was a newcomer in the land, a chechaquo, and this was his first winter. The trouble with him was that he was without imagination. He was quick and alert in the things of life, but only in the things, and not in the significances. Fifty degrees below zero meant eighty-odd degrees of frost. Such fact impressed him as being cold and uncomfortable, and that was all. It did not lead him to meditate upon his frailty as a creature of temperature, and upon man’s frailty in general, able only to live within certain narrow limits of heat and cold; and from there on it did not lead him to the conjectural field of immortality and man’s place in the universe. Fifty degrees below zero stood for a bite of frost that hurt and that must be guarded against by the use of mittens, ear-flaps, warm moccasins, and thick socks. Fifty degrees below zero was to him just precisely fifty degrees below zero. That there should be anything more to it than that was a thought that never entered his head.

Also, if there are zombies, aim for the head.


Your dad.


2 responses to “the sequence of exothermic chemical reactions between a fuel and an oxidant accompanied by the production of heat and conversion of chemical species

  1. Very good advice. Especially about the zombies. Not sure I entirely agree with the reasoning behind little-to-big. Access to oxygen is clearly important, but getting the fuel hot enough to readily partake of oxidation is, I suspect, at least as important, and probably more so. Consider that a heavy stick is not easy to light, but will continue burning once ignited. My suspicion is that the little stuff burns readily because it lacks thermal mass and thus much more readily reaches a temperature at which it is prepared to embrace all that free oxygen. Consider that a freely burning stick will often burn less well when removed from the fire, even though it should have even better access to oxygen, not needing to compete with the other burning stuff for the available oxidizer. My guess is that the isolated stick is cooled more by the air rising around it, which is more than made up for in the fire pit by the radiant heat received from the rest of the fire. That and the preheating of the air that flows past it. (From which some of the oxygen may well have been removed by lower components of the fire, by the way.)

    • thehandsomecamel

      You make an excellent point about thermal mass, of course. I suspect that may also account for heavy logs’ burning better on the lower (i.e., fireward) side, despite that being the side less exposed to the air. What it really takes to get a large log burning, then, is a super-hot bed of coals (to heat that large mass) PLUS adequate airflow on the bottom side (usually achieved by leaning the log against another log so that neither one lies flat on the bottom).

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