Long-burning wood types
The speed with which wood burns is determined by its density. The density of a tree is influenced by the quantity of water passed through its trunk. Trees with high moisture content have large veins that circulate water from the root to the leaves. When these trees are cut down, the water within these veins evaporates leaving large air gaps between the wood fibres resulting in a low-density wood. Contrarily, trees grown in dry climates like Namibia have much finer veins which, when dried, produce a much tighter wood grain of higher density. The wood fibres in high-density logs are more closely compacted than low-density wood; when ignited, high-density wood burns more slowly as the flames cannot travel quickly through the tight grains of the wood. More air gaps exist between the fibres of low-density wood – this allows for flames to travel faster through the wood and burn more rapidly.
After a tree is cut, it takes many months / years for all the water stored in the trunk to dry out. Wood which still contains high amounts of moisture is green or unseasoned and will not burn properly, often producing smoke, fumes and other pollutants. More of a fire’s energy is consumed when burning off any moisture present in green wood which makes kindling more challenging and impacts the temperature and speed of the fire. Well-dried or seasoned wood ignites easily and burns efficiently – it has very low moisture content and will burn longer than green wood. The higher the wood density, the more time required to season it, for example, Bluegum requires about 2 – 3 years to dry completely.
Hardwoods vs Softwoods
Hardwoods are typically heavier, denser, absorb less water, take longer to grow and, once seasoned, are often darker in colour than softwoods. As hardwoods are dense, they burn slowly allowing for fires of high temperatures; this makes hardwoods best suited to large fires, cooking and fuelling a fireplace or stove. Hardwoods can, however, be challenging to ignite so softwood is preferred for kindling. Softwoods come from evergreen trees which produce sap and grow faster due to their higher moisture intake. Because of the lower density of softwoods, it seasons much faster and ignites more easily. Softwoods produce more smoke when burned and are better suited to starting fires outside.
What to look for when buying wood
Before you even touch the wood you wish to buy, there are a few telltale signs of dry, well-seasoned wood you should look out for:
- The bark should be peeling, if not already totally separated (moisture keeps the wood together, so as it dries out the wood and bark naturally split).
- It’s a good thing if the wood looks faded because this is an indication it’s been left to dry out for a considerable time.
- Inspect where the wood is stored – there should be no damp areas or wet ground nearby as this means there is still moisture present in the wood.
- When two logs of dry wood are hit together, you should hear a ‘clink’ sound.
What wood burns the longest?
In conclusion, the harder and denser the wood, the longer it will burn. Start the fire with smaller pieces of wood and gradually add larger logs to avoid smothering the fire and putting out the flames. Once the fire is stable, we recommend adding dense and dry Namibian Hardwood (like Kameeldoring and Sekeldoring) for braais and fireplaces to keep the fire burning hot and long. Well-seasoned Blue Gum is also great for Closed Combustion fireplaces and works great in pizza ovens. Always remember to start your fire with Premium Firestarters / Kindling, this will make lighting the fire so much easier.