When processing wood, there are often defects in the structure of wood associated with an incorrect structure of the trunk. There are the following types of defects in the structure of wood:
1) oblique, or the slope of the fibers, which is the deviation of the fibers from the longitudinal axis of the trunk;
2) list - continuous or local in the form of a sharp thickening of wood of late annual layers;
Color and structure of palm trees
All palms consist only of sapwood, and there are no growth zones and branches; Unlike hardwoods and conifers, the inner area of the trunks is always brighter than the outer one. This difference is caused by dark, usually oval, rounded and scattered in cross-section, called vascular bundles of cell filaments. These vascular bundles, which grow from the inside outward, are enclosed in a lighter, pink-gray to brownish and thin-walled underlying tissue. The diameter of the vascular bundles ranges from about 0.5 mm to 1.5 mm, and their food bulbs form a fine, denser dark strip on all longitudinal surfaces, from the inside to the outside.
3) graininess - a sharply wavy or confused arrangement of wood fibers (wood blanks with such a defect are used in the manufacture of art products, furniture, ax handles and various handicrafts);
4) curl - local curvature of the annual layers near knots or sprouts (wood with such a defect is used in furniture production and art crafts);
Since palm trees do not form growth zones, memory cells, stripes or tree rays, the appearance of a tree is determined solely by the frequency, diameter and color of the vascular bundles enclosed in a light background. Wood, the appearance of which depends only on the vascular bundles, the distance to the center of the trunk and the height in the trunk.
lumber; glued semi-finished products; stems; Parquet. Due to the very different hardness of the bright background tissue and the dark vascular bundles, visual color sorting also largely corresponds to technical sorting: the light inner cylinder and barrel pigtail are made of the softest and most light wood, already moderate dark wood the intermediate zone is already much more complex, heavier, while the dark wood of the outer zone is heavier and heavier due to the more numerous and partially thick-walled vascular bundles; it occupies from 50 to 70% of the main volume.
5) resin pockets. They are found in coniferous wood, especially in spruce, they are cavities between annual layers filled with resin;
6) pitching - a piece of coniferous wood, abundantly impregnated with resin;
7) double core - two cores in one cross-section of a log, which are formed at the place of a bifurcation of the trunk;
Due to cell walls that still thicken with age, the wood of older palms tends to be heavier and harder in all parts than the wood of younger palms of the same species. Shrinkage is almost the same in the tangential and radial directions and increases with weight; Coconut palm hardiness is similar to hardiness softwood in the outer shell. Drying must be carried out separately according to the 3 hardness groups; The wood of the heaviest group of coconuts dries as slowly as hardwood appropriate density.
8) stepson - stunted and dead second peak, which is usually located at an acute angle;
Rice. 27.3. Defects in the structure of wood:
1 - varieties of fiber inclination: a - tangential inclination in round timber; b - local; 2 - roll: a - solid; b - local; 3 - fibrous pilus in birch; 4 - one-sided curl; 5 - pocket; 6 - double core in a pine trunk; 7 - stepson; 8 - dry side; 9 - pine cancer; 10 - progrowth: a - open; b - closed; 11 - false nucleus: a - rounded; b - stellate; c - bladed
Industrial use of wood
Too much drying will cause fine surface cracks and twisting between hard vascular bundles and less hard tissue, especially in the outer trunks of the forest at the top of the stem. For machining, all tools must be equipped, as fine mineral deposits can be blunt. For nails and screws, pre-drill; sharp edges should be avoided to prevent weakening of truncated vortices when subjected to pressure or bending stress; For the same reason, palm trees are not suitable for veneer production.
9) dry side. Occurs as a result of damage to the bark of a growing tree in the form of a dead section of the trunk;
10) progrowth. It is an overgrown wound, usually filled with remnants of the bark and dead tissues;
12) a false nucleus, which resembles a real nucleus, but differs in a more heterogeneous structure and less correct form, stands out as a dark, unevenly colored zone in the central part of the trunk, is separated from the sapwood by a dark, and sometimes light stripe, appears from the impact of fungi, severe frosts, as a reaction to wounds and for other reasons, while the wood of the false core is more fragile and less durable , and the appearance is usually worse;
Natural resistance to fungal and insect infestation is low; on the outdoors or in wet areas a deep chemical protection is required. Heat-drying paint should be avoided high temperatures due to the risk of formation of small cracks on the surface.
Light wood is beautiful. The use of palm wood is determined by the type and the corresponding bulk density or hardness group; For example, heavy coir wood is similar to oak or beech wood used in interior design, while harder and darker black palm for even heavier loads, but in smaller sizes, the same wenge or ebony. The coconut tree is heavy and medium wood for glued parts, floors, stairs, wall and ceiling coverings, seats, small furniture, countertops and counters; Black palm for deposits in parquet and marquetry, as well as for posts, handles, decorations and sports arches.
13) internal sapwood - the presence of several annual layers in heartwood, which are similar in color and properties to sapwood, and it has a reduced resistance to decay and increased permeability to liquids;
14) aquifer - a defect in wood in the form of areas with high humidity as a result of the action of bacteria, fungi, the penetration of rainwater through wounds or from oversaturation of the soil with moisture.
The use of light wood is limited due to high susceptibility. Granville, J. Schulte, M.: Economic use and use of coconut palm wood. Air dry density. AT last years this striking dark-colored and structurally high-contrast and superb technical specifications superior wood species was known to a wider group of consumers. Although wenge is one of the most high prices in African tree species, it is still cheaper than other high quality veneers such as wood veneer.
4. Fungal lesions
When cutting wood, in some cases fungal heart spots are found - abnormally colored areas of the core, which are formed in growing trees under the influence of wood-staining or wood-destroying fungi. In felled wood, the further development of this defect stops. Fungal heart spots are observed on the ends in the form of spots of various sizes and shapes of brown, reddish-gray or gray-violet colors. This defect causes: a decrease in impact strength, an increase in water absorption and water permeability, a deterioration in biostability and appearance wood; in terms of strength under static load, it almost does not change, and the structure of the affected wood is preserved.
Walnut, and Wenge is expected to receive even more attention in other areas of use. Mostly cylindrical and only rarely with a diameter of 1 m and a length without knots of more than 15 m, the lengths used are usually only up to 9 m and about 0.7 m; partly with flat bumps and slight bends.
Cordial Brown color, later dark brown and sharply demarcated sapwood. Memory cells. The pores are predominantly coarse, scattered, not numerous and isolated by dark or yellowish-gray fillings. Lovely wood beams and only recognizable on smooth flat areas through the regular floor construction. Memory cells on cross sections in most pores, light stripes connecting the rack; on the radial surfaces the thin light-dark shading and on the tangential longitudinal sections is usually very regular, the image of the wood significantly influences the resulting attenuation.
When storing wood on raw sapwood, molds often appear - mycelium and fruiting of mold fungi on the surface of the wood in the form of individual spots or a continuous coating, while the wood is stained in various colors. Mold does not affect the mechanical properties, but worsens the appearance of wood; after drying, it is easily removed, leaving dirty and colored spots.
The course of the fibers is predominantly straight or slightly twisted, usually without significant alternating rotation. Bright dark-coloured and clearly porous wood with a very peculiar, depending on the cutting direction, two-tone structural images.
roundwood, location dependent, isolated from nuclear rot or large worm. Roundwood: 0.6 to 0.8 m in diameter and over 4 m in length. Timber: Parquet: Veneers: Panels: On request, also partly finished. Raw frieze, bar and mosaic parquet. Flat cut or quarter.
In felled wood, sapwood fungi are often formed - abnormally colored areas of sapwood under the influence of wood-destroying fungi that do not cause rot. Sapwood mushroom stains do not affect the mechanical properties of wood, but worsen its appearance and increase water resistance. By color, blue is distinguished - in the form of a gray color of sapwood with bluish or greenish hues, and colored sap spots - in the form of orange, yellow, pink and brown color of sapwood. Fungi that stain sapwood can attack adhesives and paintwork.
Heavy wood with predominantly high strength properties located between Afzelia and Bongossi. In a dry state, as well as in a wet state with increased effort without difficulty, all tools must be clean; It is only in forests with irregular grain that there is a tendency to rupture. For nails and screws, pre-drill; Carbon compounds and synthetic resin based adhesives hold up well when dried. Wenge is well understood after careful fading. Natural as well as technical drying is slow with little tendency to crack and warp; Wenge has good stamina.
In felled wood during storage in the warm season, as a result of the development of biochemical processes with the participation of fungi or without them, such a defect as browning occurs. Browning of wood manifests itself in the form of abnormally colored areas of brown hardwood of various shades. Browning is observed on the ends in the form of spots of various sizes and shapes, and on the side surfaces - in the form of elongated spots, stripes or continuous damage to the sapwood, while the appearance of the wood worsens and strength and hardness slightly decrease. To prevent browning of wood, steaming of lumber is carried out.
It is very resistant to fungal attack; only as fresh logs, especially without bark, are they easily attacked by fresh tree insects. Dry wood has no smell. Wenge contains ingredients that may cause blistering, graying or delayed drying of an agent used in various preparations. Since not every veneer or hardwood, treated in the sample, behaves the same, and on the other hand, new agents are being developed, recommendations from a specialized paint manufacturer should be obtained before processing.
Great damage to wood is caused by rot, formed under the influence of fungi. Rots are distinguished by the color and structure of the lesion - variegated sieve, white fibrous; and also by types - sapwood, sound and external rotten.
Rotten wood is a source of fungal infection for various wooden structures. Rot
In general, matte, matte glossy or even finely etched surfaces are preferred. During treatment, the possible attenuation caused by strong light must be taken into account. But it also offers good strength properties and in combination with universal use decorative effect as solid wood if the price justifies the use. Since darkening of dark colors can occur with high exposure, use on a south facing location or in full sunlight should be avoided.
Veneers: for furniture, doors and walls in rooms and vehicles. The contrast effect to be achieved in combination with light details can also be achieved with stone, metal, textiles, ceramics or plastics. Full forest: for small furniture, seats, frames for showcases and showcases, as well as for parquet, stairs, decorations, cutlery drawers, jewelry and precision equipment. The aforementioned panga panga has smaller diameters and is sometimes uneven or lighter in color, but matches Wenge in other properties.
develops gradually and has three stages: at the first, only the color of the wood changes; on the second, wood partially changes its structure and hardness under the influence of rot; on the third wood completely loses strength and hardness. Depending on the stage of development of rot and the size of the damage, the quality of wood can be significantly reduced.
Therefore, it is often referred to, especially as parquet, and not as panga-panga, but as Wenge or mixed with it. Dams, K.-G.: African Export Forests. Ferdinand Holzmann-Verlag, Hamburg. Angola, Equatorial Guinea, Côte d'Ivoire, Gabon, Cameroon, Congo, Liberia, Nigeria, Zaire, Central African Republic.
In humid places, they create such extensive stocks that they guarantee a steady supply in the future. The forest of these two botanical species corresponds to each other so much that the distinction is impossible, and their use can be done together under one name.
Main physical properties wood are expressed in the features of its "reactions" to the impact of factors external environment, while maintaining both the integrity of the material and its chemical composition. In this article we will consider the properties of wood various breeds.
hardwood
Warty birch
Birch has valuable physical qualities. Its wood is distinguished by good strength. However, in hardness and density, it is inferior to some rocks. Despite this given material does not lose its industrial significance. It should also be borne in mind that warty birch is practically not resistant to decay, therefore it is mainly used in finishing works. With the help of birch, you can easily imitate the wood of many valuable breeds. That is why the warty birch is very popular with carpenters.
Abura is characterized by good stem forms, but compared to other tropical forests, they have only medium strengths, since they are also common in household hardwood. Sapwood and heartwood with no distinct color difference; fresh: yellowish-glossy. The pores are small, medium, scattered and numerous; only recognizable on smooth surfaces. Note the beams fine, the wood grain is gray to brownish gray; dried: evenly pink-gray to light brown and are unaffected.
Memory cells are not accepted. Mostly rectilinear; only sometimes with little and usually irregular alternating rotation without distinct glossy bands. Growth zones are partially and only slightly marked on smooth cross sections through narrower, poorer pores.
Beech
Beech wood is a durable and hard material. At the same time, it is highly hygroscopic and therefore prone to decay. Nevertheless, this material is characterized by high manufacturability: it lends itself perfectly to processing with any tool, under the influence of steam it becomes plastic.
Due to its beauty and unique aesthetic properties, this material is in demand in cases where finishing work is carried out. However, the widespread use of beech wood for interior design is limited by the laboriousness of polishing work.
Moderately fine and very evenly textured, colored wood. From the average tree pattern, pale yellowish or strong stems of a more reddish-brown to purple-brown heart are sometimes evoked. Wood on request in all dimensions.
coniferous wood
The latter is smooth or profiled for different purposes. Abura is located on the border of the moderate and moderately light range and strength properties between Khaya and Dibetou; with native forests, it can be compared with alder. Abura is flaky and measurable. A feature is good compressibility and deformability, which does not lead to significant violations of the cell structure and higher acid resistance. Drying proceeds as silent and chamber drying; endangered, are only more durable sizes with too fast drying and rotating parts.
Hornbeam
It has hardness, good abrasion resistance. The negative properties of the hornbeam include difficult processing of the material. Due to the big specific gravity wood makes it difficult to work with massive structures during the installation of the building. This material is prone to warping and cracking, which causes additional difficulties during its drying. All these properties of the material determine its narrow application- making tools various products increased strength, and small parts, fastening elements of individual units and entire structures.
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Pedunculate oak
Oak wood is strong and hard, highly resistant to decay. To positive properties oak wood can be attributed to satisfactory ductility to processing, high decorative properties, good hygroscopicity. From the point of view of consumer characteristics, this material is valued very highly.
The only thing that limits its use is the tendency of oak to split when driving nails or driving screws. To avoid undesirable consequences of this kind, a channel is preliminarily marked with a drill having a smaller diameter than that of the future hole.
In finishing works, as well as in construction, oak also found wide application. Stained wood panels look great in bedrooms, offices and living rooms. In addition, the room can be finished antique, if you arrange it wooden elements made of etched oak wood.
Alder
Alder is endowed with features, from the point of view of house building, both positive and opposite. The positive properties of alder wood include its softness, manufacturability in processing, moderate hygroscopicity, compliance with impregnation with a protective solution, and wide decorative possibilities.
Like birch, alder is often used to imitate valuable species. However, this material has a relatively low resistance to warping and decay. If the drying, impregnation and processing of alder has been carried out correctly, the result is a material of satisfactory quality for use in house building.
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Aspen
In terms of its qualities, aspen is not much inferior to alder, it has increased resistance to moisture. Aspen wood is characterized by high technological characteristics during processing, it is soft and light, has a uniform structure. In addition, the wood array practically does not contain knots and various kinds of defects. The material almost does not warp and does not crack under the influence of sunlight. The negative properties include the ability to quickly dry out and split as a result of exposure external factors. However, these shortcomings do not prevent aspen from successfully replacing even conifers in housebuilding.
conifers
Spruce
Due to the specific features inherent in spruce wood, its use is significantly limited. This material is used for the most part only in the manufacture of furniture. In housing construction, spruce boards are used during construction internal partitions and door blocks, in rare cases - for flooring. Spruce wood is difficult to process, it is characterized by low density and strength. The presence of numerous knots complicates the processing of spruce and reduces its value from a consumer point of view. This material is quite hard, but at the same time it is highly susceptible to negative impact moisture, which explains its non-universality.
Larch
Larch wood has established itself as a material that is resistant to moisture. high density and hardness are also its characteristics. In this regard, larch is not widely used in house building. However, due to its resistance to warping, larch is considered a valuable material in furniture production.
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Siberian cedar
It has a soft and light wood, which lends itself perfectly to processing. The material is used in the construction of structures protected from warping, as well as decay as a result of changes in humidity and temperature.
The beautiful pattern of the cedar texture allows it to be used in the production of furniture.
Fir
Despite the low resistance to decay, fir wood is widely used in house building.
This material is quite strong and dense, well amenable to processing. Using fir wood, door and window blocks, perform flooring.
Pine
Depending on where the plant grows, there are two main types of this tree. The first is called myandova pine, the second - ore. Loose and almost non-laminated wood distinguishes myand pine, which grows mainly on clay soils characteristic of the lowlands. At high humidity the wood mass of this species rots, however, this material does not cause any difficulties in processing and, in addition, is slightly subject to warping, is well saturated with water or mortar.
The place of growth of the ore pine is uplands and hills. It grows mainly on stony loamy or sandy loamy soil. wood mass has a fine-layer structure, moderate density, resinous. Thanks to these qualities, ore pine occupies an honorable place in housing construction. It is used for laying the ceiling and floor, constructing internal partitions, walls of the log house, as well as the roof.
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