I’ve written previously about how to light a fire but haven’t really mentioned much about what makes good firewood, or indeed what isn’t so good. Hopefully this post will put that straight., As a heads up, I’m focusing on being in the woods and sourcing firewood rather than ordering it up for your wood burner at home, although some of what I write here is still applicable in that situation too.
I often get asked about what’s the best firewood to use and it’s similar to the question “What’s the best knife?”. Sage heads will point out it’s the knife you have. With firewood, the best firewood is what you have. I could extoll the virtues of beech and why you should only use beech, but if you’re in a conifer forest you are unlikely to find much of it! But if you have a choice then there are a few things to consider.
Whether you find yourself in a broadleaf or conifer woodland it’s gong to be crucial that you gather seasoned wood, that is, wood with a very low water content. Now you’re unlikely to have any scientific equipment with you to measure this so you’ll have to go for some more basic methods.
- If the piece of wood is small enough to snap in your hands, give it a try. It should snap with a sharp ‘crack’; if you have to wrestle with it, if it has leaves or buds attached, if you see any green colouring in the wood, it’s very likely that it won’t burn well, so don’t bother with it.
- If the piece of wood is too big to snap easily, put the end to your lips. Your lips are surprisingly sensitive and will feel any moisture in the wood.
The best way to find dry wood is to avoid any that’s on the floor. This is especially important if it’s raining or has been raining recently, so look for stuff that’s hung up.
We work in a mixed broadleaf woodland and have around 25 or so different species. This means we have some choice in what we can use. Assuming that everything we come across is in the same condition, a key consideration is how much heat a particular wood will produce.
If you take a kilogram of any wood and burn it, it’ll produce exactly the same amount of heat, which is an interesting fact but doesn’t help us much! But bear in mind that a kilo of oak will be much smaller than a kilo of balsa. So if we take a cubic metre of wood and burn it and measure how much heat it produces, we get a much more useful indicator. In the UK this gives us, in order of most heat produced to least:
This list comes from ‘Norwegian Wood’ by Lars Mytting. There are a few obvious species missing from the list, notably cherry, hawthorn, hazel and sycamore. I’ve found that hazel and hawthorn make good firewood and cherry is an especially good, long burning firewood. Also missing from the list are sweet chestnut and alder, which I’ve found to be a particularly poor firewoods.
If you’re looking for a long burning fire to keep you warm over night then you need to be looking at firewood from the top of the list.
A great example that highlights the different quantity of heat produced comes from when we run our courses on the Isle of Arran. We base ourselves in a conifer forest mainly consisting of larch and spruce; these are pretty low on the density scale, burn noticably quicker, spit embers at you, and produce less heat to the extent that we don’t use the ‘star lay’, but rather have a big blaze under the kettle to generate enough heat to get the water boiling. We go through much more firewood than we do at our own camp.
Woods to avoid
There are woods that you want to avoid burning as firewood.
Some woods are renowned for spitting sparks and embers. This might not be an issue if you’re using a wood burner but if you have an open fire, especially one you’re sleeping next to in a debris shelter, be careful. Top of the list are resinous conifers such as pine, spruce and larch. Beech and sweet chestnut are broadleaf spitters.
The chemicals produced as a result of burning wood are toxic regardless of the species you’re burning and to this end you want to avoid breathing in smoke at all costs, even is some do smell particularly pleasant! The danger from breathing in smoke is from the fine particles produced. These microscopic particles can get into your eyes and lungs and can cause burning eyes, runny nose, and illnesses such as bronchitis. They can also make asthma symptoms worse and trigger asthma attacks.
But some woods contain other toxic chemicals. It’s surprisingly difficult to find information on the toxicity of woods when they’re burnt, outside of folklore. Ones that I’ve heard described as toxic are elder, yew, laurel and laburnum as well as rhododendron, although I’ve also heard conflicting reports for the latter one.
We do plenty of fire lighting on our 5 Day Bushcraft Course, 2 Day Bushcraft Course, IOL Bushcraft Competency Course, plus most of our others. You can see loads of photos of all of our courses on our Facebook page.