A simple and accessible tool for understanding the fundamental terms related to wood. From the meaning of sapwood and heartwood to the characteristics of texture, grain, and density. A useful resource for professionals, citizens, and students who want to familiarize themselves with the language of the sector.
Document reporting rules of practice or procedures for the design, manufacture, installation, maintenance, or use of products, structures, or equipment.
Change in units of volume corresponding to the increase of one degree of temperature from a given initial temperature. It is usually reported as an average coefficient relative to a certain temperature range. In the case where instead of volume the dimensional change along a certain direction is measured, it will be referred to as the “coefficient of thermal expansion.”
Statistical parameter expressing the dispersion of values from the mean value. It is given by the ratio, usually expressed as a percentage, between the standard deviation and the mean of a set of values referring to the examined property.
State in which components of the same substance are held together by primary and secondary attraction forces. In bonding, the term denotes the condition under which the components of the adhesive (or adhering) are held together internally.
Breakage of the gluing at the wooden portion of the joint (glue line). It is expressed quantitatively as the percentage of the glued surface that shows breakage in the wood (also called “Adhering failure”).
Gluing operation in which an assembly is subjected to pressing without heat administration (i.e., at room temperature).
Gluing using an adhesive that cures at a temperature below 20 °C. The term also refers to adhesives that cure at environment temperature.
Drying defect due to localised implosion of a group of cells and which macroscopically results in alveolar cracks or surface undulations.
Zone where the root system and stem join. It corresponds exactly to the position of the seed in the substrate at the time of germination.
Detachable element formed by solid walls and spaced laths employed to hold the load in box pallets.
Establishment of fungi or other microorganisms in the wood.
Difference between the surface colour of the decorative veneer and the control colour or sample veneer colour. It does not include the colour difference between primitive and late wood, nor the colour difference of the natural grain on the surface of the wood itself.
Wood veneer obtained either by a bleaching or dyeing process.
Laminated laminated timber having a cross-section consisting of inner and outer laminations with a different strength class or manufacturer’s specific strength class.
Combined glulam with asymmetric cross-sectional layering.
Substance that is oxidized during a combustion process. It is usually rich in carbon and hydrogen.
See “Anobium puctatum”.
Wood species Scientific name: Juniperus communis L.
Companion cell of a sieve tube member intimately connected with it. It has permanent nucleus and dense cytoplasm. Note: Companion cells may undergo transverse divisions or in other planes before their differentiation.
Kiln in which the entire charge is exposed to the same seasoning conditions for the entire time throughout the process.
Dynamic defense process in an injured tree that creates structural and chemical barrier zones to hinder the propagation of pathogens.
Body designated by an EU Member State for the application of Reg. (EU) n. 995/2010-EUTR.
Complaint for a given product or service provided not corresponding to what was requested.
The dimensions of a workpiece at any stage of manufacture when its measurements correspond to those specified, generally with the tolerance of 1 cm in length and 1 mm in width and thickness.
Laths of mosaic parquet having equal size and arranged to form a square.
Plywood panel whose core (or certain layers) is made of materials other than solid wood or wood sheets. It comprises at least two cross-grained layers arranged on each side of the core.
Collection of all test samples from the sampling units taken from the batch according to the sampling plan chosen for the determination of retention.
Rigid coating consisting of a top layer (thickness greater than or equal to 2.5 mm) of wood and other layers of other wood substrate material or wood-based products of less than 75% in mass.
Generic term used to refer to materials and products formed from small elements glued or otherwise connected together.
Description of plywood constituent elements
Deformation characterized by two or more bows in different directions.
In wood anatomy, it is a conventional term for the compound layer between the secondary walls cell of adjacent cells. It consists of two primary cell walls and an intercellular layer of varying thickness.
Deformation consisting of two or more springs having different directions.
Improved wood whose cell walls have been impregnated with a synthetic resin and then compressed to reduce deformation and increase density and mechanical strength.
Solid biofuel obtained by mechanically compressing biomass in order to increase its density and shape it into desired size and shape (e.g., pellets and briquettes).
Application of a stress in one direction such that it causes compaction or densification of a material.
Failure resulting from compression applied along the grain, either by toe compression or bending.
Breakage or cracking of wood cells caused by excessive compression parallel to the grain determined by axial compression or bending stress. It may occur in standing trees due to wind stress or snow loading, development of internal stresses from accretion, or may occur later due to stresses imposed during or after felling. On a sanded timber, the failure may appear as a series of fine transverse corrugations clearly visible on the surface of the piece.
The condition whereby one or more dimensions of a piece of wood remain slightly smaller than normal: in green wood due to compression during drying; in dry wood because swelling is prevented when it is humidified. Note: A longitudinal deformation from internal compression can be artificially caused to achieve desired effects.
Breaking strength value determined following a compression test.
Dialectal denomination. See “compression wood.”
Wood that occurs in the lower portion of the cross-section of branches and in the sloping stems of conifers. Anatomically, it is characterized by a rounded cross section of tracheids, the presence of helical cracks, and increased lignin deposition at the cell wall of the tracheids. Compression wood is identified macroscopically by the greater width of the growth rings, the generally eccentric cross section, the usually darker color than normal wood, the formation of a greater portion of late wood (occupying more than 50 percent of the width of the entire ring), and the lack of an abrupt transition between early and late wood within the same ring. It also exhibits much greater axial shrinkage than usual.
It certifies that a product complies with a mandatory application standard: for example, the CE Mark certifies compliance with EU directives and compliance with the essential requirements contained therein.
Surface of a sawn timber that will be permanently hidden by other components after installation in the final product.
Written authorization for the use or delivery of a specified quantity of materials, components or stock already produced but not meeting specified requirements. Concessions should refer to defined quantities or time periods and specific uses.
System consisting of spacers and paneling framework into which reinforced concrete is poured to provide setting. Generally, exterior environmentally bonded plywood coated with a phenolic film or surface resin coating is used for the paneling. Such paneling allows for well-solid, durable, easy-to-handle, strong and lightweight form-work. Furthermore, its unique insulating properties result in low temperature variations and consequently particularly suitable setting conditions.
1) Physical process by which there is a change from a vapor state to a liquid state. 2) Chemical reaction in which two or more molecules combine together with the separation of a molecule of water or other simple substance.
See “dehumidification drying”.
Kiln with a series of hot water hoses aimed at removing excess moisture from the air after the load has left.
General term for an inspection to evaluate the condition of a structure.
The adjustment of the moisture content in processed timber or other material in line with the conditions it will be used for. It is carried out in special conditioning chambers, and is also intended to facilitate the penetration of antiseptics. More specifically, it is the treatment applied at the end of seasoning to reduce the moisture gradient between pieces or to bring the moisture content to the desired level: this operation is called “equalization phase”.
Stage at the end of the drying process or prior to the equalizing stage. During this phase residual stresses or hardened surface crust can be mitigated, preferably by employing high temperatures and high relative humidity values.
Wood durability achieved through preservative treatments.
Coalescent aliform parenchyma forming irregular tangential or diagonal bands in cross section.
Compliance of a product, process or service with all the requirements specified in a particular standard, law or contractual specification.
Cells of the same anatomic type.
Spore of asexual origin typical of fungi imperfecti.
A tree belonging to the main group of the class Gymnosperms.
Conifer introduction in coppice forests, especially if sparse or degraded, to provide better ground cover and to increase production of working timber.
Fungus belonging to the Basidiomycetes. It causes brown rot to softwood and hardwoods. It is found in particularly moist wood, construction, or wood in contact with soil.
Special type of parenchyma associated with included phloem. Note: Sometimes it occurs in the form of anastomosed concentric bands, (for example, in Avicennia), or including phloem chordae, (for example, in Strychnos).
Two or more elements joined together by mechanical means, adhesives or a combination of these.
A coupling device placed between or on the components or members to be connected and held in place with dowel-type fasteners.
Sending goods by appropriate transport vehicles.
Water chemically bound in the woody cell structure.
Regulation (EU) 305/2011 concerning the placing and free movement of construction products on the European market.
An adhesive that is apparently dry to the touch but able to adhere instantly upon contact with itself. It is also called a “dry adhesive (glueing)”.
Angle between a flat substrate and the free surface of a liquid droplet along the line of contact with the substrate.
Gluing failure due to lack of contact between the glue and the surface to be bonded caused by insufficient glue flow, irregular application or uneven surfaces.
Installation without contact between wood and the application unit.
Implementation of phytosanitary measures in and around an infested area in order to prevent the spread of a pest.
Pest transported by a commodity, package, conveyance or container, or occurring in a storage place and which, in the case of plants and plant products, does not infest them.
1) Gluing with a machine that provides the required heat and pressure to a pack that is driven toward it forming a continuous product. 2) In any gluing, the preparation of a continuous film over the entire surface to be glued.
Line connecting points of equal elevation on topographic maps.
See “contour line”.
Document reporting an agreement between two parties.
Any relevant material accompanied by a phytosanitary certificate (or an approved alternative) and subject to a phytosanitary inspection.
Change in the form of forest governance (e.g., coppice to high forest or to compound coppice and vice versa).
The processing of rough timber into products for various purposes. A distinction is commonly made between primary manufacturing (debarking, topping, cross cutting , etc.) normally executed in the forest, and secondary processing, which includes subsequent processing and finishing in the factory.
Stage at the conclusion of the drying process during which the cell and its load are cooled so that the timber can be discharged from the kiln without damage.
Hardwood forest agamically reconstituted after each periodic cut by issuing coppice shoots. Coppice is denoted “simple” if no stem or sucker is spared from cutting. It is “coppice with standards” or ” compound” if a certain number of matricine, i.e. seedlings and shoots intended to grow to ensure the necessary dissemination for the renewal of stumps (by gradual substitution of stumps that gradually become depleted) as well as to provide a certain amount of timber for work. Coppice is said to be “steered” when only a portion of the shoots (those that have reached a certain size and smaller ones in supernumerary) are cut at each cut.
Stem that originates from an adventitious or dormant bud located at the base of a plant that has been cut.
In the plywood industry, this term is used to indicate the visible central layer along the edges of a final panel, generally thicker than the other layers and consisting of: – laths or lamellas of wood that are joined together and glued or unglued; – another wood-based material; – another sheet material; – a honeycomb construction.
In a plywood, discontinuity between two contiguous elements of an inner sheet or core that do not look perfectly matched or joined together. Sometimes the defect may also be evident on the surface of the panel.
An open veneer joint that extends through, or partially through, a plywood panel. Product standard PS 1 states that the average of all gaps may not exceed 1/2 inch and that every effort should be made to achieve tightly-fitting core joints.
In plywood composed of an odd number of layers, it consists of the inner layer containing the symmetry plane parallel to the plywood faces. In the case of plywood consisting of an even number of layers, it consists of the two middle layers glued together with parallel grain. They therefore form a split core layer and the symmetry plane of the plywood corresponds to one of the bonding planes.