Fire - Good or bad?
Fire gives us warmth and light and something to cook on. Learning to light a fire could save your life - Its one of the most useful things you can learn in Forest School.
BUT fire eats fuel and is never satisfied. If it could fire would burn everything from forests to houses. It burns and injures. Its smoke can blind and sting, its flames can change direction and lick your clothes or flesh with its fiery breath. Water heated on a fire scalds and blisters. Even if there are no flames the embers can be red hot just under a layer of ash so fire creates doubt - is that fire out or just waiting to relight?
I used to work at a coal power station, have a wood burner, made campfires from being a boy and yes inevitably I've been burnt (nothing too serious I'm glad to say). I've lots of experience of how dangerous a fire can be and also how useful.
Fire and the Law
As fire can be so dangerous it can lead to severe punishment by law. Arson (deliberately setting a fire to cause damage) is nearly as serious as murder (up to life imprisonment) because it recklessly endangers lots of people, property and wildlife. Lighting a fire can be subject to environmental law (particularly if you're burning rubbish) and civil law if it causes non-criminal damage (such as accidental damage) which may aggravate other laws such as trespass.
We have licence agreements with land owners that stipulate how (or if) we use fire so that fires can be lit legally and safely with minimal impact.
Fire at our sites
At Fairy Forest School we only use fire when we need to (which in winter is most of the time so we can get warm) and with the express permission with the land owner. Some land owners such as the Woodland Trust insist we use a fire pan off the ground to protect the soil. Soil can contain lots of organic material and at some sites the soil (especially peat) can 'burn.' At sites with a special conservation status we may not use fire at all.
Smoke can be a nuisance to local residents - who wants washing smelling of smoke! So we endeavour to light fires well away from a site's neighbours.
A common on the ground method is to use stones to contain a fire. However the heat can cause some stones to explode so that's a method we don't use. Instead we keep fire safe by monitoring it. You leave it at your peril - so we'll never be far from the fire. We'll also have water on hand to contain the fire if it does spread and quench it at the end.
We also need to have clean cold water available just in case to treat a burn. A moments mistake can lead to a burn but if its treated immediately with water then it may not even blister or require further first aid.
The fire triangle
Fire needs 3 things - fuel, air and heat. Take one away and the fire will go out. Don't provide one and it won't even light. Wet wood absorbs heat and so will cool a fire. You can smother a fire with too much fuel. And if you haven't a heat source such as a flint and steel then it'll just sit there staring at you whilst you freeze.
Build me a fire
Before you even get to lighting a fire then you need to build it. Before you build it you need materials. We usually bring our own wood because its bone dry to get it going. We collect dead wood that's off the ground and less likely to be damp. Children often gather wet wood so sometimes we leave that to dry by our fire to use later.
We raise our fire pan on fresh or rotting wood logs such as coppiced hazel (where allowed) or old birch. This helps to insulate the ground from the heat. We place the pan on top and use logs on the pan to create a raised border to help contain the hot ash on the fire pan. Across that we lay sticks to resemble a waffle with lots of gaps for air to flow through. On top of that we put natural firelighters (such as made from beeswax) or birch bark and lots of fine sticks. We lean larger sticks over this to resemble a pyramid.
Over the fire we have a hazel coppiced tripod interconnected at the top and impaled into the ground. This gives the location of the fire height and lets you dangle a Billy can over the fire if you want to cook. The tripod acts as a natural barrier to the fire and helps prevent anyone getting too close. Some forest schools use logs to sit by the fire to create a danger zone. These are nice especially for larger fires but if you don't have logs then the tripod is a good option. A disadvantage of logs is they're a trip hazard and you might trip and end up face first in a fire. Ouch!
You can buy iron tripods but these conduct heat and aren't obvious when they're hot. The hazel only ever gets warm for the short periods we use them. Over a sustained period they may catch fire so get ready to add them to the fire and make some more. One more advantage discovered by forest school students on a wet day is to lean wet sticks on the frame to dry before placing on the fire. Remember we're not leaving the fire so its safe as long as its monitored.
We place cotton wool by the kindling and firelighters to catch the spark from a flint and steel and 3-2-1-ignition - the fires going.
The tree of fire
Silver birch is our favourite tree. Its quick growing and beautiful especially in Autumn when it looks like its made of silver (bark) and gold (leaves). Its great for fire. The bark if peeled acts as a natural fire lighter but don't take more than it yields by finger tip alone otherwise the tree is more prone to disease. The ends of the branches yield lots of fine twigs which is wonderful kindling - we don't take these off the tree as there's usually lots of wind damage twigs beneath them that are dry. Seasoned birch burns magnificently but you'll not find that in a wood without significant planning or unless its fallen and got lodged off the ground. Birch left on the ground rots quickly and soaks up water like a sponge - great for woodlice but poor for firewood.
And finally the leave of birch looks like a little flame. Particularly in Autumn when they go red/brown/gold.
People rave about Ash which can be burnt green due to its low moisture content. We only burn dead wood and never any green living wood. Lots of people rave about ash but I suspect that will change with the advent of Ash Dieback disease. People will see a healthy ash and leave it well alone because they will start to become rarer and rarer. Dieback ash will be fair game for burning.
btw - Seasoned ash isn't as good as birch but it does season quicker.
The science of fire
The ancient Greeks thought fire was an element. They got that wrong!
Fire is a chemical reaction where fuel (or carbon) combines with oxygen to make carbon dioxide (a waste gas) and water vapour. You need some activation energy for this to happen (hence you need heat for ignition) but the reaction is exothermic i.e. it produces heat. That's why fire can be so devastating because its a chain reaction or self sustaining - as long as there's air and more fuel it'll keep on going.
The heat turns volatile organic compounds (VOCs) in the wood into a gas that burns - in a similar way that a candle flame turns liquid wax into vapour as it rises up a wick and into the flame. This is what a flame is. Smoke is unburnt fuel. An efficient fire (like my woodburner) ensures all the smoke is burnt. So if your fire makes a lot of smoke you're wasting valuable fuel.
When the flames die down the solid carbon remains. This pretty much resembles charcoal. This solid carbon reacts with oxygen giving off heat and red light. These are the embers or hot coals of the fire and can carry on burning with little visible flame. Often forest school pupils say the fire is out at this stage even though its producing lots of heat. Chuck some kindling on and it reignites straight away producing lots of flames much to the surprise of those adamant its out! A bed of embers is great to cook on because they're so hot and unlike a flame won't move around with the wind.
After the fire
We cool it down and smother any unburnt fuel with lots of water. We take any half burnt sticks and scatter them ensuring they're soaked and cool. Any black embers we scatter. This is a great fertiliser or potash but can be toxic if left in the same place time and time again. That's why its important to scatter and also its part of our leave no trace policy.