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The flammability of wood is a measure used to describe wood that will catch fire easily under normal circumstances when there is an ignition source. Various types of wood have different burning characteristics and heat content. The two main categories of wood are hardwood and softwood. Hardwoods are deciduous or leaf-shedding trees with a higher degree of density than most softwoods. Softwoods weigh less and are generally not as dense as hardwoods.
Softwoods are evergreen trees like conifers that maintain their leaves throughout the year. Softwoods ignite more readily than hardwoods because the wood of softwood is resinous. Softwood also tends to burn quicker than hardwood. Some species of hardwood, like pines, contain little pockets of moisture and gases that cause the wood to pop or explode when burning. Softwoods also tend to throw off sparks more frequently than hardwoods. Types of softwood include several species of pine, like yellow pine, Eastern white pine, Western white pine, Jack pine, White and Pitch pine. Other types of softwood include Douglas fir, willow, spruce, redwood and balsam fir.
Hardwoods are generally heavier than softwoods. They do not ignite as readily as softwoods, meaning that they are less flammable. They also tend to burn longer and less intensely than softwoods. Examples of hardwood include species of birch like grey birch, black birch, white birch, paper birch and yellow birch. Other types of hardwood include cherry, American elm, walnut, white elm, sycamore, blue beech, pecan, hickory and dogwood.
Bamboo is another type of wood that can be used for construction or as firewood. Even though bamboo is considered wood and is used to make things like flooring in homes, it is technically a type of fast-growing woody grass. It is still wood, and it has the same characteristics as softwood. Bamboo burns very quickly and throws off a lot of sparks. It also tends to burn very intensely.
Factors Affecting Flammability
The factors affecting the flammability of wood include factors like moisture and the degree of seasoning. A well-seasoned wood is one which has been properly dried to remove its moisture content. More than 50 per cent of the weight of freshly cut wood is water. Green wood is much less flammable than dry or seasoned wood. Green wood tends to produce a lot of smoke as it uses the heat to burn off the excess water to allow combustion to take place.
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