BUILDING PROPERTIES AND USABILITY
DOMESTIC TYPES OF WOOD

Several thousand woody species that differ from each other in botanical, histological and technological characteristics provide unlimited opportunities for scientific research in this area. However, despite this, the lack of funds and the lack of economic interest meant that, from the anatomical and partly technological side, a little over 250 types of wood have been processed so far, of which about 50 types of wood are of greater economic importance. On the botanical side, the number of wood species that have been researched and even systematically processed in great detail is much higher.

In our country, there are about 20 types of wood of industrial importance, of which only a few are more important. The most important local wood species include: beech, oak, spruce, fir, and pine. There are fewer other species, so their economic importance is lower.

For a more detailed introduction to domestic coniferous and deciduous wood species, we will provide an overview of data on the structure, properties, and industrial usability of the most important wood species in our country.

TECHNICAL PROPERTIES OF WOOD

POPLAR (Populus nigra L.)

The distribution area of black poplar is in Europe, the former countries of the USSR, Turkey, North Africa, and India.

The poplar tree is about 30 m tall. The crown is sparse, wide, and with many branches. The bark of young trees is smooth and light gray, later cracks longitudinally, and takes on a dark gray color. The thickness of the bark is up to 12 cm, and its share is about 12.6% of the volume of the tree. The density of the bark is about 412 kg/m3. The length of the black poplar trunk is up to 15 m, and the chest diameter is up to about 1 m.

Black poplar belongs to the sailing tree species. The sapwood is white-yellowish and wide. The heartwood is yellow to reddish-brown. Growth rings are barely visible. The tracheas are diffusely and porously distributed. The wooden strips are low, thin, and homogeneous.

The density of black poplar wood in the absolutely dry state is – 490, in the dried state – 450, and raw 750 kg/m3. The volume share of pores is about 73%. The total linear stresses of wood are axial 0.3%, radial 3.3 to 5.2%, and tangential 7.1 to 9.8%. The total volumetric weight of poplar varies from 10.7 to 14.3%, and the specific volumetric weight is from 0.36 to 0.48%.

Poplar wood is machined well, the optimal processing speed is about 40 m/s. It grates, cuts, peels, and chips well. It dries well, but due to the presence of reaction wood, it is prone to deformation. The surface is processed well, but it is poorly lacquered. Poplar wood is used in the production of veneers, plywood, and construction boards, as solid wood for the production of furniture and for interior furnishing of buildings. Its special purpose is for the production of chips for fibers, paper, and cellulose, wood wool, etc. It is used for the production of wooden crates for fruits and vegetables, as well as for the production of transport packaging.

ELM (Ulmus carpinifolia Gle.)

Polish elm is widespread in Central, Southern, and Western Europe, North Africa, and Western Asia. The altitude distribution of elm is from 700 m/asl to about 1300 m/asl in the Swiss Alps.

Elm is a deciduous tree with a trunk height of 20 to 30 m, a trunk length of up to 10 m, and an average trunk diameter of 0.5 to 2 m. The crown of the tree is wide, with many large branches, of which the upper ones are upright, and the lower ones are slightly lowered. The bark of the trunk cracks quite early. On old trees, the bark is dark gray-brown, longitudinally furrowed. The volume share of bark is about 15.6%, and the density is about 400 kg/m3.

Elmwood is fibrous, sapwood yellowish-white to dirty-yellow and narrow. The heartwood is brown-red to dark-brown. Growth rings are striking. Tracheae are ring-shaped. The contrast in color between early and late wood is great. The wood strips are homogeneous and angularly invisible.

The density of elm wood is: in the absolutely dry state from 440 to 820, an average of about 640 kg/m3, in the dried state from 480 to 850, an average of 680 kg/m3, and in the raw state of moisture from 750 to 1050 kg/m3, average 850 kg/m3 m3. The volume porosity of wood is 58%. Total linear strains of elm: axial 0.3%, radial 4.3 to 4.8%, and tangential 6.9 to 8.3%. The total volumetric weighting is 11.8 to 13.8%, and the specific volumetric weighting is 0.39 to 0.46%.

Elmwood is machined well, and hard to plane. It turns and bends well, when joining with nails and screws it is necessary to pre-drill to avoid splitting. Birch dries well, although it is prone to weathering and cracking, after drying it acquires a darker color. The wood has a good surface treatment, although due to the high surface porosity, it is necessary to fill the trachea beforehand. The durability of the wood is great and in changing conditions is 8 to 12 years. It is used for making furniture, veneers, parquet, weapon stocks, wooden pipes, boats, thresholds, sports equipment, etc.

WALNUT (Juglans regia L.)

The distribution area of the walnut is central, western, and southern Europe, and it is also cultivated in Asia Minor, North Africa, Northern India, and China. Its altitudinal distribution in Central Europe is up to 850 m/asl, and in southern Italy, it grows even up to 1800 m/asl. Walnut trees can be over 100 years old.

Walnut trees generally reach a height of about 25 m. The length of the trunk is up to 8 m, and the diameter is usually up to 1 m, rarely larger. The crown of the walnut tree is very wide, oval, with many thick branches. The bark of the trunk is smooth, light gray when young, and later cracks longitudinally.

The Walnut is a deciduous type of tree. The sapwood is grey-white and narrow, and the heartwood is dark-brown to black-brown, mostly with dark stripes. Raw wood smells like leather. The growth rings are striking, relatively wide, and concentric, and the tracheas are diffusely-porous and large, visible. The strips of wood are thin and low, homo and heterocellular, and difficult to see. Axial parenchyma is unilateral and zonally diffuse.

The density of walnut is: in an absolutely dry state – 640, in a dried state – 680, and in a raw state up to 1100 kg/m3. The porosity of walnut is about 57%. The total linear weights are: axial 0.5%, radial 5.4% and tangential 7.5%. The total volumetric weighting is from 13.4 to 14.0%, and the specific volumetric weighting is from 0.25 to 0.45%.

Walnut wood is good for peeling, cutting, planing, and sanding. Requires light drying. It sticks well. The surface is well processed, well stained, varnished, and painted. Walnut is used for the production of cut and peeled veneer, then in the production of furniture and for the interior lining of buildings, and for the production of panel boards and parquet. Walnut is also used as a special wood for turning and marquetry, then for the manufacture of musical instruments, for the manufacture of rifle stocks, and for other purposes.

BLACK PINE (Pinus nigra Arnos.)

The distribution area of ​​black pine, which has several subspecies and varieties, is located in southern Europe, northern Africa, and Asia Minor.

The pine tree is evergreen and up to 40 m tall. The crown of the tree is wide and oval. Trees grow on poor and rocky terrain when their canopy can be in the shape of an umbrella. The trunk is straight and up to 20 m long, and the chest diameter of the trunk is up to 1.2 m. The bark of the tree is gray-brown to black-gray, rather thick, cracks at an early age and gets deeper longitudinal and shorter transverse cracks.

Pine wood is fibrous, the sapwood is yellowish-white, narrow or wide, and the heartwood starts between 40 and 60 years of age. The pith is reddish-brown, in the fresh state there is no significant difference in the color of the pith and sapwood, but later, due to the decrease in humidity and oxidation, the pith becomes reddish-brown. Growth rings are striking, and the transition from early to latewood is abrupt. Resin canals are numerous but barely visible. The wood strips are barely visible on the radial section, and while they are not visible on the transverse and tangential section, they are thin and heterocellular.

Black pine wood is medium-heavy and its density is: in an absolutely dry state of moisture about 580 kg/m3, in a dried state about 620 kg/m3, and in a raw state about 1000 kg/m3. The total linear weights are axial 0.4, radial 4.3, and tangential 7.74%. The total volumetric weight of pine is about 12.6%.

Black pine wood is very durable. It is used in construction, carpentry, aviation industry, furniture industry, etc. Because of its great durability, it is especially valued as a mine wood and as wood for exterior use in the production of windows and doors, etc.

PINE WHITE (Pinus silvestris L.)

The distribution area of white pine is quite wide and includes the area of Europe and Northern Asia. Its altitudinal distribution is from 700 m/asl in the northern mountains to about 1600 m/asl in the southern mountains.

The pine tree is evergreen, 10 to 30 m tall, with trunk length up to 20 m, and chest diameter up to 1 m. The crown is tall, oval-conical, and lets in a lot of light, that is, it is quite sparse and lighter in color than the black pine crown. The trunk is slender and straight. Branches are arranged in vertebrae. The bark of young trees is thin, reddish-gray, later it is grey-brown in the lower parts, deeply fissured, while the upper parts of the trunk and branches still have a yellowish-red bark, which is of a small consistency and peels off in small flakes. The volume share of bark is from 12 to 18%, and its density is about 300 kg/m3.

Pine belongs to the coniferous tree species. The sapwood is yellowish-white or reddish-white, and the heartwood, when fresh, is similar to the sapwood, while in the air it later becomes reddish-brown. The boundaries of the growth rings are clear and distinctly dark in color. The resin canals are predominantly in the middle part of the ring and increments and can be seen in the cross-section as dark spots, and in the longitudinal section as thin strips. Tree bands are hard to see and heterocellular.

The density of the wood is: in the absolutely dry state – 490, in the dried state – 510, and in the raw state at 820 kg/m3. The volume porosity of the wood is about 67%. The total linear stresses of wood are axially 0.4%, radially 3.3% to 4.0%, and tangentially 7.5 to 8.0%. The total volumetric weighting is 11.2 to 12.4%. Specific gravity is 0.37 to 0.41%.

Scots pine wood is easy to cut, plan, drill and sand. Optimum cutting speeds are around 33 m/s. The wood dries well, and at a humidity above 25% and a temperature of 20 to 30°C, it tends to appear blue. Wood sticks well. The surface is processed well, although with a high resin content it is difficult to stain and varnish. The durability of the wood is great, especially when used underwater.

White pine wood is used for the production of cut and peeled veneer, for the production of veneer panels, and for the veneering of chipboards. Wood is used for the production of doors and windows, for outdoor use, and for the production of floors and roof structures. It is used as a special wood for the paper and pulp industry, for the production of chipboard and fibreboard, in the production of wood wool, charcoal, etc.

FIR, ordinary (Abies alba)

The distribution area of ​​fir is in central, western, and southern Europe. Its altitudinal distribution is about 800 m/asl in the north to about 2000 m/asl in the Pyrenees.

Fir is an evergreen tree, whose trunk height is 30 to 40 m, although specimens of 50 and more meters can be found. The length of the trunk is 20 m, and the chest diameter of the tree is up to 1 m. The crown of the tree is conical when young, and later more cylindrical. The branches are arranged horizontally in the form of vertebrae, and the twigs do not hang. The bark of young trees is smooth, light gray later cracks and darkens. The volume share of bark is about 11.5%, and its density is about 460 kg/m3.

The fir wood is bulging, yellowish-white to reddish-white in color, growth rings are striking, and the transition from early to latewood is gradual and somewhat more abrupt than that of spruce. The wood has no resin canals, the wood strips are thin and invisible. The wood is generally of a regular texture, sometimes it contains charred wood, and twisting of fibers and waviness of the line of growth rings at the point of their intersection with the strips of wood can be encountered.

The average density of fir wood is: in the absolutely dry state – 410, in the dried state – 450, and in the raw state up to 900 kg/m3. The volume porosity of wood is about 73%. Total linear stresses are: axial 0.1%, radial 2.9 to 3.8% and tangential 7.2 to 7.6%. The total bulk density is 10.2 to 11.5%, and the specific bulk density varies from 0.34 to 0.38%.

Fir wood machines well, peels, cuts, plans, drills, and sands well, holds nails and screws well, dries well and quickly, turns hard, carves well, stains well, and slightly worse varnishes with acid and with base varnishes, it is difficult to impregnate. Wood is used as a construction material for internal installation, then for construction underground and under water. It is used for the production of musical instruments, in the pulp and paper industry, in the fiber board industry, in the production of wooden packaging, etc.

SPRUCE (Picea abies Karst.)

Spruce is distributed in the mountains of central and southern Europe, in the north it extends to Scandinavia, and its southern border is the mountains of the Balkan Peninsula. Its altitude distribution is from 1500 m/asl to about 2000 m/asl.

The spruce tree is evergreen, reaching a height of 30 to 50 m. The length of the trunk is up to 20 m, and the average chest diameter is up to 1.2 m. The canopy is regular and conical. The branches are thin and vertebrally arranged. The twigs on the branches are up to 50 cm long and more. The bark of the tree is thin, in its youth it is smooth and gray for a long time, later it becomes scaly and takes on a gray-reddish color. The volume share of bark is about 12%, and its density is about 340 kg/m3.

Spruce wood is glabrous, yellowish-white to brownish-gray, and shiny. Sapwood is slightly less glossy than mature wood. Growth rings are emphasized, and the transition from early to latewood is gradual. The wood contains resin canals, individual and mostly distributed in the latewood, invisible to the naked eye. The strips of wood are thin, heterocellular, and invisible. The wood sometimes contains split wood, and there are also defects in the form of irregularities in the flow of the fibers, twisting of the fibers, or wavy grain lines at the point of intersection with the strips of wood.

The average density of spruce wood is: in the absolutely dry state of humidity – 430, in the dried state – 470, and in the raw state at 800 kg/m3. Spruce volume porosity is about 71%. The total linear stresses of wood are: in the axial direction 0.3%, in the radial direction from 3.5 to 3.7%, and in the tangential direction from 7.8 to 8.0%. The total volumetric weighting is 11.6 to 12.0%, and the specific volumetric weighting is 0.4%.

Spruce wood is well scraped, planed, drilled, sanded, and polished. It is easy to turn and holds nails and screws well. It dries well and quickly, but it is prone to creasing and warping. Wood glues well, stains well, but is difficult to varnish. It is particularly difficult to impregnate and offers little resistance when varnishing with acid and base varnishes.

Spruce wood is used as veneer wood, as a construction material, for exterior and interior construction, roof constructions, paths, and stairs. Its special purpose is for the production of musical instruments as resonance wood, then in the production of wood wool, brushes, paper, cellulose, then for the production of chips for fiberboards, chipboard, etc.

ASH (Fraxinus excelsior L.)

Common ash is distributed throughout Europe and in the northern parts of Asia Minor. Its altitude distribution is from 650 m/asl to about 1400 m/asl in the mountains of the Southern Alps.

The ash tree is 25 to 35 m high, and the length of the trunk is 15-20 m. Trees up to 300 years old reach a chest diameter of up to 1 m. The canopy is oval and rounded. The branches are thick and mostly directed upwards.

Ash has a thin, smooth, and greenish-gray bark when young, which turns yellow-gray in age and becomes shallowly smoothly furrowed. The volume share of bark is about 13.9%, and its density is about 457 kg/m3.

The density of ash wood is: in an absolutely dry state – 650, in a dried state – 690, and in a raw state up to 1140 kg/m3. The volume porosity of ash is 57%. The total linear stresses are axially about 0.4%, radially 4.6 to 5.0%, and tangentially from 8.0 to 8.4%. The total volumetric weighting is 12.8 to 13.6%, and the specific volumetric weighting is 0.43 to 0.45%.

Ashwood works well by hand and machine, plans and turns well, dries and glues well. Ash wood, in principle, has a good surface treatment, although it is poorly stained. The wood is straight, splits well, and bends easily.

Ash is especially valued in the production of cut and peeled veneer. It is used for the production of furniture, parquet, as structural wood, for external and internal use. The special purpose of ash wood is for the production of sports equipment, then for the production of stylish furniture, in shipbuilding, wagon building, aircraft and machine industry, and in other areas.

ACACIA (Robinia pseudoacacia L.)

Acacia was brought to Europe at the beginning of the 17th century and now its distribution area is in Europe, North Africa, and New Zealand. The tree reaches a height of up to 25 m, a trunk length of up to 10 m, and a chest diameter of about 0.8 m. The crown is sparse, if the tree is isolated, then it is round, and if it is in a stand, then as a rule it is oblong.

The bark of the acacia tree is smooth and gray when young, later it is thicker and acquires a gray-brown color with longitudinal cracks. The volume share of the bark is up to 10%.

Acacia is a deciduous tree species. The sapwood is very narrow (3 to 6 growth rings). Growth rings are striking. Tracheae are arranged in the form of rings. The contrast in color between dark late and light early wood is great. Tracheae of early wood are usually surrounded by parenchyma and later filled with tissue, visible to the naked eye in transverse and longitudinal sections. Wood bands are thin and low, homocellular, less often heterocellular, and visible on axial sections.

The density of acacia wood is: in an absolutely dry state of humidity – 740, in a dried state – 770, and in a raw state 900 kg/m3. The volume share of pores is about 52%. The total linear stresses of acacia wood are: in the axial direction 0.1%, in the radial direction 4.4%, in the tangential direction about 6.9%. The total volumetric weight of wood is from 11.4 to 12.2%. The specific volumetric weight is about 0.4% per 1% hygroscopic humidity.

Acacia wood machines well turn and cut well. Holds nails and screws well. Drying of acacia should be done slowly because it is prone to blowing, warping, and cracking. Acacia sticks well, but more pressure is needed. The wood is well surface treated and varnished. The durability of acacia wood is great.

Acacia wood is used for fences, vineyard stakes, for turning, for the production of furniture, parquet, and stairs, due to the high impact voltage it is used for the production of tool holders, then for the production of mine wood, wooden barrels and for various other products.

OAK ORNET (Quercus petraea)

Ornate oak is a tree from the oak family, Fagaceae family. Other popular names for oak kitnjak are brdnjak, gorun, beljik, črepinjak, graden, štilik.

Ornate oak reaches a height of 40 meters and a breast diameter of 1 to 3 m. The bark of the tree is much thinner and more shallowly fissured than that of the oak tree. Buds are brown, bare, and conical-pointed. The leaves are from 8 to 12 centimeters long, inverted ovate lobed, on the lower side less hairy along the midrib. The petiole is 1 to 3 cm long. The fruit is an acorn, shorter and thicker than the acorn of the common oak, uniformly light-yellow in color. It has a less luxurious crown than the oak. Oak acorns grow in groups of 2 to 5.

It does not occur on wet soils, it grows poorly on limestone substrate, and it is acidophilic. Its forests have been largely cleared for agriculture. It is a heliophilic species, resistant to dust and atmospheric pollution. Its wood is of very high quality. It grows in forests up to the age of 120 years. This is his optimal maturity. Physiological maturity is up to 1000 years.

Ornate oak grows in the hilly and mountainous terrains of Central and Southern Europe, as well as Western Asia. It is widespread in Western, Central, and partly Eastern Europe. The range limit in the north is up to 60°. The eastern border is a line from southern Sweden, through Poland and Ukraine to the Black Sea, the southern border goes through northern Greece and Spain, and the western border runs through the continental part of France all the way to Ireland in the northwest.

The bark of the trunk is light gray, quite thick, deeply longitudinally, and shallowly fissured transversely. The average share of bark is about 19.3%, and its density is about 425 kg/m3.

The oak wood is fibrous, the sapwood is yellowish-white and narrow, and the heartwood is yellowish-brown. The oak wood is fine, shiny, sometimes with an irregular texture, with the appearance of sparkling and matted fibers. The growth rings are striking, the tracheae are ring-porous, and the wood strips are very large.

The density of oak is: in an absolutely dry state – 650, in a dried state – 690, and in a raw state of moisture up to 1150 kg/m3. The porosity of oak wood is about 57%. The linear stresses of oak are axially 0.4%, radially from 3.5 to 4.7%, and tangentially from 7.7 to 10.0%. The total volumetric weight of oak is from 12.2 to 15.0%. The specific volumetric weight of oak at 1% hygroscopic humidity is about 0.45%.

Oak is generally machined well. The optimum speed of movement of the blade during cutting and peeling is about 33 m/s. Oakwood holds nails and screws. It generally dries well, although due to the occurrence of collapse and cracks, it requires slow drying. Oak generally sticks well, although stains may appear on the glued surfaces. It can be stained, varnished, and painted well. During processing, corrosion of the tools used to process oak wood may occur.

Oak is a highly valued technical wood and has a very wide range of applications. It is used for the production of railway sleepers, shipbuilding, construction, carpentry, in the furniture industry, then for the production of veneer and parquet, for mine wood, then as tannin wood, for the production of wooden barrels, as firewood and wood for coal.