Wood is the very first material that people learned to process. Even today houses are built from it, it is used for interior decoration or furniture manufacturing. In all these works, such a parameter as the density of wood is important. This is a very unstable value, which depends not only on the type of wood, it can vary from one specimen to another within a fairly wide range. In addition, different density can be in one piece of wood. Therefore, all values are averaged.
The different density of wood is explained by the cellular structure. Wood consists of wood cells of different sizes, shapes, differently oriented in space. All cell walls consist of one substance with a density of 1540kg/m3, but the structure and their sizes are always different. The density of the wood depends on this. The larger the cells, the more porous and light wood, with a decrease in the size of the cells, the density increases.
Bwithin the same species of trees, the specific gravity may vary depending on the place of growth. For example, a tree grown in a dry area will have a greater density of wood than one that has grown in a swamp. This parameter also depends on age: the older the plant, the denser its wood.
To a certain extent affects this indicator and humidity. The more water the cells contain, the heavier they are. But since this indicator changes rapidly, all data are usually given at a certain humidity. How hard or easy it will be to process the material also depends on such an indicator as the density of the wood. The table in which the averaged results of practical measurements are entered must contain in the explanation an indication of the humidity for which the values are given.
To achieve optimal density, a technique such as drying is used. There are two types of this process: natural and technical. With natural drying, materials are stacked in ventilated stacks, which dry under the influence of natural conditions. During technical drying, wood is placed in specially equipped drying chambers, in which certain humidity and temperature are maintained. In such chambers, the wood is brought to the required moisture content.
Depending on the density, wood can be divided into:
- light (pine, poplar, cedar, linden);
- medium (elm, beech, ash, birch);
- heavy (maple, hornbeam, oak).
With increasing density, the mechanical properties of wood also change: its tensile and compressive strength increases. The denser the wood, the easier it is to process. Therefore, pine, whose density is low, is used more often for construction or for rough carpentry work, and oak, which has a high density, is considered one of the best carpentry species. Although good products can be made from pine, the denser wood of oak looks much more attractive, and oak products last much longer, chips and dents are less likely to appear on them. When using pine products, you need to be extremely careful: any mechanical impact can leave a mark. But dense wood is poorly impregnated. For example, it is easier to treat pine with antiseptics than oak. However, dense wood is less prone to abrasion, which is important for stairs, railings and floors. The task of what type of wood to use in certain works is up to you, but you need to consider all factors.
