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The log is undoubtedly the oldest form of wood fuel known to mankind. Until today, logs are the most traditionally used wood heating system for domestic heating.

Logs come from forest harvesting and hedgerows where the wood quality and dimensions are not sufficient for so-called noble uses, such as sawing, slicing or peeling. Hardwood is often preferred over softwood because it more dense and does not contain any resin. To obtain a good fuel, the wood must be dry. Therefore trees are usually cut in winter when the sap no longer circulates. For the wood to dry properly, it is cut in logs of one meter, which are then split along their length. This allows the wood to dry more quickly (bark effectively hinders the evaporation) and not to be the target of mushroom attacks, but it also eliminates much of the bark, which is not necessarily desirable. It takes between one and two years of natural drying and for the wood to reach less than 25% moisture content. Some more industrial processes allow the wood to be dried in ovens, which reduces the drying time to just a few days. The logs are then re-cut to the desired size by the end-users, generally 33 or 50 cm.