101 Ways to MAKE FIRE - #7 The Devil's Breath

Описание: Today, I show you how to make char-cloth (a magic material you will encounter often in fire-making videos) and also show a cool way to start a fire at the same time. Devil's Breath is a term sometimes used by firefighteres to refer to the noxious brew of gases cuased by incomplete combustion of organic material. When people die of smoke inhalation it is usually these gases that are to blame. Carbon dioxide will suffocate you mostly by replacing the available oxygen in the air, it isn't really toxic. But these gases can incapacitate you within seconds. Almost everyone knows the acrid smell of charring material and will recoil or retreat instinctively, or react by coughing, sneezing etc. We are designed or adapted to find the smell very unpleasant. THESE GASES ARE POISONOUS. DON"T TRY THIS WITHOUT ADULT SUPERVISION. Most people don't realise that "things" don't actually burn. Flammable substances like grass, wood, rubber etc (even petrol / gasoline) don't combust directly. What happens is that the heating of these materials causes a chemical breakdown that results in the release of flammable gases. This is called pyrolysis. Once the temperature of the gas reaches its ignition temperature, it bursts into flame. It is these burning gases that we recognise as fire. But the process of combustion requires oxygen too. In the absence of oxygen, we get charring. Most of us are familiar with charcoal. The process of making it is very simple and can be observed along many rural roads in the developing world. A stack of wood is set alight, but is covered with a mound of earth. In the absence of air, we get something called incomplete combustion. The wood cannot burn. Instead it chars. Normally, when you burn wood, all the carbohydrates combine with oxygen to form carbon dioxide and water vapour. All that is left is the fine ash resulting from the small amount of minerals in the wood. (This is why ash is such good fertiliser). With charring, the basic cellular structure of the material is retained. First, all the moisture in the material is evaporated off, followed by heavier oils, tars etc. Then the carbohydrates start breaking down into a recipe book of unusual organic compounds like aldehydes and alkanes and so on (okay, organic chemistry wasn't my favourite subject; I wish I'd paid a bit more attention though). Most of these are very volatile, flammable, explosive, whatever you want to call it. Basically, they're floating around, all energised like some Ritalin kid, just looking for oxygen to bond with so that they can release that energy and go back to being something more docile. What you're left with is basically pure carbon. Charcoal. Which will burn very nicely, thank you, but won't really give off any flames because all those flammable gases are already gone. The cool thing is, because there are no gases to blow away, the more air you add, the higher the temperature you can achieve. By adding the limiting ingredient, you speed up the reaction (which is exothermic) and more energy is released. When it comes to starting fires, this property of charred carbon is very useful, because it allows us to take a small spark or ember and grow it until it is giving off enough heat to ignite our tinder bundle.
In today's exercise, we are making charcoal on a much smaller scale than the forest harvesters of Zambia or Zaire. A chunk of charcoal would not work very well as an ember catcher because it is too big. Too much heat would be conducted away through the material and the temperature of the spark would drop to below the ignition point. Also, it is a solid chunk, meaning that not very much oxygen can get to the point of contact. If we char woven organic cloth however, we solve these problems. Whilst your clothes might look reasonably solid, at a microscopic level they are full of holes. The gaps between the woven strands ensure a free flow of air to the point of contact of the spark. And because there is only a thin layer of material, the energy of the spark is all concentrated one a single strand of the material. Even if the spark only lasts for a second, there is enough time for it to transfer its energy to that tiny piece of carbon and get it hot enough to start glowing. So that's why we make char cloth. And in the process, we get a little rocket engine going as well. I really like the sound that the flame makes as it shoots out of the little hole. Sort of a whistling hum. The tin acts as a bit of a soundbox, amplifying the song. A merry little fire song. The tunes I was whistling during the breaks were Light my Fire by The Doors and Ring of Fire by Johnny Cash.
DISCLAIMER: This video was filmed over the course of 2 days. I changed flint lighters half way through. I had a good dinner, prepared by my "crew", that did not involve grubs or scorpions. And it's been edited. Call it fake if you want to.... At least I'm not pretending to light a fire using only a potato...