For as long as we have had it, humanity has had an incredible link with fire. For our ancient ancestors, fire provided warmth, protection from wild animals, light in the dark wilderness, and a place to cook food. While fire is no longer vital to most people’s existence, it still has a magnetic power that attracts us. The flames of fire can inspire legendary stories, generate discussion, and build camaraderie among those circled around them. In forest schools, the fire is most likely to be used as a warm place for discussions, cooking, and as an inspiration for children’s creativity.
In order to successfully make a fire, that will last for the full time you are spending in the woods, you need to keep in mind the three things every fire needs, known as the fire triangle. It is also important to know the fire triangle in order to stay safe, as knowing how to remove one of these aspects, and therefore extinguish the fire, is extremely useful to know. As you can see in the picture below, the three aspects are Oxygen, heat and fuel. Oxygen is the easiest of the three to provide, as the fire will simply take Oxygen from the air around it. Oxygen can be removed from a fire using Carbon Dioxide, powder or foam fire extinguisher, all of which prevent oxygen reaching the fire. In addition to this, sand and dirt could be used in a forest setting. Fire blankets also work by denying a fire Oxygen, however given the sizes campfires can be made these may not be suitable. If using a fire extinguisher, you should take care because the high speeds at which the substances are ejected from the nozzle can scatter burning materials around the area.
The second aspect is fuel. This can mean anything from paper to flammable liquids and gases, however in forest schools the most commonly used form of fuel is wood. Wood burns at fairly low temperature, igniting at temperatures between 150 and 260 degrees Celsius. Generally, forest school practitioners tend to let their fires extinguish themselves naturally by stopping adding wood towards the end of the session so the fire consumes the available fuel then goes out due to lack of fuel.
The third, and final, aspect of fire is heat. Heat is produced as a result of exothermic chemical reactions in the fire between the fuel and oxygen in the atmosphere. This allows fires to sustain themselves and expand, as a small area of fire will produce heat, allowing a larger area of fuel to ignite, producing more heat. This cycle will ensure that fires expand as far as they can within the constraints of the fire triangle. This is why fire sites are generally raised, in a hollow, or surrounded with a ring of stones all of which allow us to control the amount of fuel provided to the fire, limiting the size of the fire. Without heat, fires will not be able to sustain themselves, which is how water extinguishes fires. Water extinguishes fire as it has a high heat capacity due to the energy needed to break the bonds between molecules leading it to change state from liquid to gas. When water is put on a fire, it absorbs the heat from the air and the fuel, lowering the temperature to below the level needed to sustain a fire and extinguishing the fire. The initial heat needed to start the fire can come from many sources, such as matches, lighters, friction and even lightening! In my next post I will be exploring how these initial heat sources work, which is the most effective, and how to best build a fire. In the meantime, I hope this has helped you and if you have any questions don’t hesitate to ask!