Wood Glossary

A production worker who examines semi-finished products and wood-based products and assigns them a quality class on the basis of certain criteria laid down in standards, specifications or contractual agreements.

In forestry, it is defined as the slope of the ground surface, of a track, of a trail, with respect to the horizontal plane. It is usually expressed in % and corresponds to the tangent of the slope angle.

Description of the different wood qualities and how they are to be determined. Note: Grading rules for round timber and sawn timber have been established for both international trade and individual national trades in order to better meet the needs of buyers. These standards vary widely depending on the purposes pursued. As a result, a precise correspondence between one language and another cannot always be determined.

Particleboard in which the particles have been distributed in such a way that the finer ones form the outer layer and the coarser ones the opposite layer.

Operation consisting of inserting into a plant a part of another plant of a different species or variety.

Term not to be confused with ‘texture’ or ‘veining’. It is the prevailing direction (sometimes also the size, arrangement, appearance or quality) of the main anatomical elements (fibres or tracheids) in a stem or semi-finished product. In a standing tree, the fibres run parallel to its growth axis and determine the greatest strength characteristics along that direction. Similarly, semi-finished products and structural wood-based panels must be laid in such a way that the direction of the grain (which usually also corresponds to the largest dimension of the element) is perpendicular to the supports.

Cork reduced to granules that can be dissolved or agglomerated together.

Wood durability test performed by placing the test samples in contact with the ground and exposed to the weather.

Aerial transport system consisting of a steel wire or rope (supporting rope) stretched between two points at different levels. It is used for gravity transport, in free descent, of loads of moderate weight suspended from hooks or blocks that slide on the rope.

In a tunnel dryer, an area where the woody material is introduced into the plant.

Removal of coppice shoots.

See ” green timber”.

Timber not yet dried and with high moisture content, generally above the saturation point.

Wood species Scientific name: Alnus incana (L.) Moench Origin: Europe

Marine borer crustacean belonging to the genera Cherula or Limnoria.

A shaping cut in the side and/or head of an element (e.g. for flooring), intended to receive the tongue of a flanked and/or attested element. In the furniture industry it is also called a “groove”.

In pressure processes, total amount of impregnant absorbed by the wood before the recovery stage.

See “gross absorption”.

In-situ treatment that involves the application of wood preservatives to the ground line area of poles. NOTE This is generally used to increase the durability of treated poles.

Perido of cambial activity.

Period of time that in temperate-cold climates generally runs from spring bud opening to winter rest. This is the time during which cambial activity (wood production) takes place, in contrast to the period of vegetative rest.

Biomass of woody material consisting of the total epigeal volume (i.e. excluding roots) of standing trees in a forest.

See “growth ring”.

Layer of wood or bark apparently produced during a growth period. Frequently, especially in woods of temperate zones, it is divisible into early and late wood or bark.

Periodic growth layer of the wood of a tree, often clearly visible in a cross section of the trunk where it appears with a concentric course around the pith. It generally includes a portion of early wood and a portion of late wood and varies in width depending on various factors related to the growth of the tree. In Regions characterised by seasonal interruption of vegetative activity, the rings of woody species are easily distinguishable and, since the period is generally annual, this makes it possible to estimate the age of the tree.On the other hand, in some woody species in temperate climate zones and in many tropical species, the growth rings are often scarcely or not at all evident. The width of the rings and the proportion of early wood and late wood are also used as indicators of wood quality.

Stresses that develop during the differentiation of the wood cells and the growth phases of the plant, also in relation to external phenomena. They are in equilibrium in the standing tree while at times they can free themselves and cause negative effects (cracks and deformations) following felling.

Behavior of a forest species or subspecific entity with regard to different environmental factors. In other words, the degree of its sensitivity with respect to variation in the factor being considered. For each environmental factor, there is a minimum, a maximum and an optimum of intensity: a species is the more “demanding” the closer to the optimum the conditions it requires and the higher the value of the optimum; it is the more “plastic” the greater the width of the interval between the minimum and maximum (between tolerance limits) for the factor considered. The main environmental factors are: temperature, light, water and soil fertility. In regards to temperature, forest species are divided into “microtherms” (cold climates), “mesotherms” (temperate climates), “macro or megatherms” (warm climates), and again into ” rustic” (which can withstand temperature extremes and especially frost) and “delicate” (which are sensitive); with regard to light into “heliophilous or lucivagous” (light plants) and “sciaphilous or shady” (shade plants); with regard to water into “xerophilous” (undemanding), “mesophilous” (moderately demanding) and “hygrophilous” (very demanding); with regard to soil fertility into “frugal” (undemanding) and “demanding.” Finally, there is a social temperament according to which forest plants are distinguished into “sociable or gregarious” (when they form monophytic communities) or “sporadic” (when they live alone or in small groups, isolated or within mixed forests).

Tunnels between 10 and 50 mm in diameter, caused by larvae in standing tropical trees.

Wood species Scientific name: Leplaea cedrata Origin: West and Central Africa

Interface documents between a European Directive and technical standards drawn up by CEN. Their purpose is to guide the drafting of standards with regard to the affixing of the CE marking.

Chainsaw cutting element that supports and guides the chain. It determines the direction of cutting.

In saw blades, it is the connecting area between two successive teeth. It is more or less rounded according to the type of teeth and intended to collect the sawdust being removed. In planing machines, milling machines, etc.: the part of the tool holder, connecting two successive knives, which is more or less hollowed out to compartment to facilitate the removal of small chips.

Wood species Scientific name: Eucalyptus sp.p. Origin: Australia, coltivated in Europe.

A term that includes non-volatile, viscous plant exudates that generally dissolve on contact with water. Their chemical structure is complex and they can be regarded as highly polymerised carbohydrates. Many substances considered or called gums are actually oleoresins.

Intercellular canal containing gum. It is also called the gum duct.

Resin streak-like mark frequently observed in hardwood.

Union of two veneers edge-to-edge using a strip of gummed paper, prior to overlapping. The paper is removed before sanding.

Procedure in which a saline impregnant in the form of a paste is injected, by means of a hollow needle, into damp wood where it penetrates by diffusion.

See “anchor cable”.

Botanical name of the group of vascular plants provided with flowers that produce seeds that are not contained in an ovary. Coniferous is the most important order.

External appearance, habitus of the whole plant (crown, stem and roots). The natural habitus is that of plants grown in the isolated state under normal vegetative conditions.

Wood species Scientific name: Celtis australis L. Origin: Mediterranean basin; mainly used as an ornamental species and in roadside trees.

Small cracks or splits produced by the knife action on the underside of rotary cut veneers.

Thin but perceptible discontinuity (similar to the trace of a hair) sometimes noticeable at the contact surface between two joined pieces of wood.

Veneer in which the pattern given by the wood grain features only half of a cathedral figure.

Pair formed by a simple pit and an areolate pit of adjacent cells.

Timber cut or split lengthwise through the middle into two halves that are half logs.

Francism used to indicate a sheet produced by peeling where the workpiece is fixed to the machine with a special bar (known as a ‘stay-log’) that allows to obtain a surface pattern different from that achieved by fixing the workpiece to the mandrels in the traditional way.

Machinery that utilises a set of hammers pivoted around a fulcrum and a perforated grid to reduce bark, culls and large particles into minute particles for use as fuel or in panel production. The size of the particles obtained is controlled by the openings in the grid adjacent to the hammer path.

A generic term to refer collectively to the bunching, extraction, and transport operations of wood and timber.

Part of the bark that consists of fibers or other supporting cells, sometimes in concentric layers that alternate within a growth ring with layers of soft bark, or more irregularly distributed in a fundamental tissue of soft bark. A layer of hard bark formed at the end of the season (as in oaks and chestnut) is called the terminal layer.

Wood species Scientific name: Acer nigrum Michx. e Acer saccharum Marsh. Origin: North America.

Thin homogeneous fibreboard with a density greater than 0.40 g/cm3.

See “case-hardened timber”.

A substance or solution used in the formulation of an adhesive mixture intended for gluing plywood or a wood-based panel. It is added for the purpose of promoting or controlling (e.g., by changing the pH) the polymerization reaction of the adhesive (resin) by taking part in it. In fact, it is also called a “catalyst”. Additives include many salts of strong acids or bases. One of the most commonly used is ammonium chloride. The term is also used to refer to a substance added to control the degree of hardness of a film after it has polymerized.

Wood property indicating its resistance to penetration. It is normally well correlated with the density of the sample.

Wood from trees botanically included in the category of Angiosperms Dicotyledons, predominantly represented by deciduous species (e.g., oaks, maples, ashes, walnuts, poplars). The English designation “hardwood” is not always indicative of the actual hardness characteristics of the material. The wood of hardwoods is called “heteroxyl” because it consists mainly of two different types of cells, one with a mechanical support function (fibers), the other with a conduction function (vessels), as opposed to the “homoxyl” wood of conifers.

Veneer assembled with multiple contrasting colours in a random selection.

Standards relating to the same object, approved by bodies with regulatory activity. They ensure the interchangeability of products, processes or services, or the mutual understanding of test results or information provided in accordance with the standards.

Set of attachments and devices made of leather, rope, and metal that are applied to draught, saddle, and cargo animals.

Surface roughness more or less extended, caused by micro-cracks on the surface of the veneer.

Combined machine used in the forestry sector to carry out the operations of felling, cutting and limbing the stems. The structure consists of a frame with 6 or 8 wheels and a central joint that allows movement in inaccessible areas. An arm with a gripper equipped with a chainsaw and two jointed toothed rollers is mounted on the front. The pliers hook the tree keeping it firm and stable, while the chainsaw cuts it close to the ground. The tree is thus controlled in its fall by being gripped at the base by the tongs; when it touches the ground, the two toothed rollers make the stem slide along the tongs, thus removing all the branches. Furthermore, at intervals established by the operator, the rollers stop to allow the chainsaw to cut the tree into pieces from 1 to 8 meters in length. In this way it is very quick and easy to obtain customized pieces from a whole tree ready to be loaded on a truck. These machines require very powerful motors to operate the boom’s large hydraulic system. The engine is typically located in the rear of the machine, behind the elevated cab. This is equipped with every comfort, such as interactive on-board computers and in most models it is mobile, to favor the best visibility in the work area.

See “feller”.

See “hatchet”.

Tool consisting of a steel head with one or two sharp edges, threaded through a handle. It is used for cutting trees, processing logs, and woodworking.

In yarders, it is a steel rope, driven by a winch, whose function is to pull, brake, and hold the carriage from the direction opposite to that of the mainline. Its length is therefore normally twice or more that of the first mainline.

Operation of wood handling, whereby trees, trunks or logs, partially or completely prepared, assembled in loads, are carried to a landing following striproad.

Wood species Scientific name: Corylus avellana L. Origin: Europe (excluding the northern part), Caucasus, Asia Minor, North Africa.

Part of the carriage of a sawing machine on which the log is supported and held. It consists of a base, hook-bearing uprights, alignment devices, etc.

A board containing the pith.

Portion of sawn timber containing the pith along all or part of its length.

Any localized rot in the heartwood or in the center of the cross-section of a stem or trunk. It usually occurs on the standing plant.

Radial-developing crack originating from the pith. It is visible on the end top of round timber.

Radial terminal fissure originating from the pith. Note: Cracks other than these occur as a result of boundary detachment during felling or sawing.

See “heartwood”.

Rot located in the heartwood.

Physiologically inactive central portion (no longer containing living cells and no longer conducting sap) of the wood of a standing tree that extends between the pith and sapwood. It is distinguishable from the surrounding circular crown of sapwood by its generally darker colour (in differentiated heartwood species) and greater natural durability (resistance to biodegradation agents). This characteristic is due to the frequent presence in the heartwood of phenolic compounds, gums, resins and other substances with antiseptic properties. Note: in French, the term “duramen” is only used to indicate the heartwood of those species in which it is distinctly darker than the sapwood.

Controlled drying process, in which heated air circulating within the cell is mixed with fresh air (inlet) so that evaporated water vapor from drying wood is removed (outlet) by discharging some of the circulating air through controlled-ventilation ducts.

See “dehumidification drying”.

A treatment usually performed after pressing on hard fibre boards in order to increase their mechanical properties and resistance to moisture changes. A similar treatment is performed to temper steel and increase its hardness.

Slight alteration of wood (usually after felling) due to fungal attack. It occurs with colour changes and results in a reduction in technological propertie

Thin metal plate heated by low-voltage current used to accelerate the setting of glues.

See “heating-up phase”.

Initial stage of the drying process during which the cell and the load of timber are heated and humidified to selected initial values of the drying regime. The phase can be distinguished into two times: one related to the heating of the dryer structure and one related to the heating of the timber through its thickness.

Increase in height of the stem of a tree plant.

Plastic or light alloy headgear designed to protect the head from falling objects or accidental impacts.

Chemical substance similar to cellulose that decomposes (hydrolyzes) easily on contact with weak acids giving rise to several simple monomeric carbohydrates (sugars) with five (pentoses) or six (hexoses) carbon atoms.

Figure obtained by placing the silver grain in the opposite direction to that of the adjacent pieces of veneer.

Insect of the Cerambycidae family present in southern Europe. It attacks exclusively the sapwood of certain hardwoods. In some cases, however, damage may extend to the heartwood.

Timber with or without a bevel that is finished to size using hand tools such as an axe.

Wood species Scientific name: Carya sp.p. Origin: Noth America.

Plywood coated with a resin-impregnated fiber overlay in order to provide extremely smooth and hard surfaces that require no additional finishing and have high resistance to chemicals and abrasion. The cover material is glued to both sides of the plywood as an integral part of the panel faces. It is used for concrete forms, cabinets, highway signage and countertops.

Forest population (and ecosystem) whose plants born from seeds are destined to be raised on tall trees and to be renewed sexually. They can have natural or artificial origin (after planting).