Burning wood directly from the tree is, generally speaking, a bad idea. Freshly cut logs – also called “green” logs – have a high moisture content, which prevents them from burning well. For that reason, most people who burn logs use either air- or kiln-dried logs. But what’s the difference?
Air-dried logs are green logs that suppliers leave to dry out in wood stores. Over many months, moisture in the logs evaporates into the air, yielding a dry log. Typically, air-dried log vendors begin the drying process early on in the year. They then store wood in warehouses and rely on high summer temperatures to warm the wood and accelerate moisture loss. By the time the winter comes around, the logs are ready to burn. Air-dried logs tend to retain their natural colour well. Gentle drying does not disturb the wood resin they contain, keeping the wood brown. At a certain point in the drying process, logs reach an equilibrium point where there is equal transit of moisture between the logs and the surrounding atmosphere, and vice versa. Once this occurs, the logs are ready for use.
Kiln-dried logs are different. Manufacturers place these into large ovens, as the name suggests, at high temperatures, usually 170 degrees F. Applying heat speeds up the drying process and removes more moisture content from the logs than air drying alone. Kiln drying reduces the moisture content of the logs to around 6 to 10 per cent, depending on the species. Usually, kiln-drying takes between 10 hours and a couple of days, instead of months. Kiln operators closely monitor the drying of the logs, checking that the interior dries at the same pace as the exterior. Once the logs are dry, the manufacturer must then store them indoors away from sources of moisture. This practice reduces the chance of mould or fungal buildup during storage.
Which is better?
Most people with wood burners choose kiln-dried logs. That’s because they are affordable and guarantee a good burn. However, air-dried logs are a good option for those who want their firewood to retain more resin and colour. If you're looking for high-quality logs for your home, shop our range at London Gases today.