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.
Decay of aesthetic characteristics or physical-mechanical properties caused by biological agents.
Energy derived from biofuels.
Fuel directly or indirectly produced from biomass.
Probability of wood decay due to xylophagous organisms, related to the wood species and the environmental conditions in which the wood is in place. The risk can be: – low; – medium; – high.
Amount in grams per square metre or kilograms per cubic metre of a wood preservative (as a product) proven effective in the test to prevent the attack of a particular tested biological agent.
Material of biological origin, excluding material contained in geological formations and transformed into fossil material.
Degradation of wood caused by biological agents such as fungi, insects, bacteria and marine borers.
Wood species Scientific name: Betula pubescens Ehrh. o Betula pendula Roth. Origin: Europe. Other species are in Central and North Asia and North America.
Hole or damage in the trunk caused by birds.
See “birds eye figured wood”.
Wood characterized by the presence of small, localized portions where twisted grain forms a few to many circular or elliptical figures that, when viewed on a tangential surface, resemble the outline of a bird’s eye. They are sometimes found in maple wood and some tropical timbers.
Abnormal blackish colouration that may occur in the heartwood of some species (especially in Ash). It is not necessarily associated with the presence of carigenic fung
Insect hole in which the walls are blackish in color. Such coloration is an indicator that the insect attack is over.
A knot partially or totally black in color.
Black knot not exceeding 5 mm in diameter.
Wood species Scientific name: Populus nigra L., including the varieties pyramidalis Spach and italica Duroi. Origin: Central and Southern Europe, Caucasus, Siberia, Western Asia, North Africa.
Blackish colored area that occurs along the growth rings in some broadleaf trees.
More or less rigid steel blade with teeth on one or both edges. Each type of blade is characterized by the geometry of the teeth (throat, back, tip and face) and their working angles (angle of attack, rake and beak, the sum of which equals 90°).
Veneer that has undergone bleaching.
Treatment of wood performed to lighten its colour and make any differences in colour tone homogeneous. It is usually performed on plywood panels.
Leakage of impregnating liquid from the surface of wood after treatment.
Exudation of the adhesive mixture through the outer sheet of a plywood panel, which may manifest itself in the form of stains. This defect can also occur with other types of semi-finished products and wood-based panels involving gluing and/or joining of smaller unit elements.
Equipment in which the adhesive mixture is additivated to a cluster of particles in the production of a recomposed panel.
Colour variation noticeable from a distance of 2 m to 2.5 m that does not affect the overall appearance of the veneer.
Small longitudinal barley grain-shaped cavity on the curved surface of a round wood. It is generally hidden by the bark.
Separation of circular extent between layers of a plywood caused by the absence of adherence. It may constitute a serious defect due to delamination between inner layers or a minor defect visible in the form of a localised detachment between an outer and underlying lamina resembling a skin blister. In this case, its appearance may still be globular and raised or the blister may have popped and appear flattened. The blister is caused by the vapour pressure that develops during the pressing phase, which can be caused by a high humidity in the ply, an excessive coating of the adhesive mixture or a too high pressing temperature. In the most severe cases, the vapour pressure may determine a peculiar noise similar to a bang.
Device for clamping semiautomatic carriages on the skyline of a yarder.
Structural element with rectangular cross-section consisting of two or more glulam components bonded together with a gap-fill adhesive.
Core plywood in which the core consists of solid wood laths between 7 and 30 mm wide, glued or not glued together. According to the new European regulations, composite plywood is now, to all intents and purposes, a category of plywood.
See “core plywood”
Strips of timber that are nailed between the main frame members in order to support the edges of the structural panels at the point where they meet.
Occurrence of crystals on the surface of the treated wood caused by the exudation and evaporation of the preservative solution solvent.
Crystal formation on the surface of an impregnant-treated wood caused by migration of one or more components of the impregnant to the surface and evaporation of the solvent.
Wood seasoning kiln equipped with turbine fans placed outside. Note: in opposition to kilns with normal propeller fans, which can be placed inside or outside.
Length of the path of circulating air through the wood stack.
Grayish discoloration of sapwood, with bluish or greenish shades. This alteration is caused by ascomycetes and imperfect fungi that mainly use the wood’s reserve substances, therefore the wood’s mechanical strength characteristics are not substantially altered. Blue stain is usually limited to the sapwood but in undifferentiated heartwoods it can affect the entire cross-section of the log.
Staining of the sapwood of wood in service due to the growth of fungi with pigmented hyphae within the wood cells.
In a broad sense, it is an assortment of sawn timber over 1 m long and significantly wider than thick (usually between 18 and 34 mm), trimmed to parallel or non-parallel edges or untrimmed. For softwood boards, Italian standards state: (a) the normal board 4 m long, more than 16 cm wide and 10 to 80 mm thick; (b) the normal board of increased length from 4 to 6 m; (c) the submeasure board with a length of 4 m, width of 8 to 15 cm and thickness of 10 to 30 mm. For hardwood boards, there are no detailed standards except for the length, which must be more than 1 m.
See “foot”.
Semi-finished work that can be used as a sub-floor.
Large category of sawn assortments in which the cross-section shows significantly greater width than thickness. The term is used in contrast to squared timbers, in which cross-sectional dimensions are little different, at most one twice as large as the other.
A piece of hard wood or iron, mostly cylindrical, with a sharp point and often with a head. It can be embedded in a wall or elsewhere.
The collapse of the adhesion between two layers
Bonding created through the use of an adhesive which is usually applied to semi-finished wood-based products in the form of an adhesive mixture. Most bonding operations for the production of wood-based panels require the curing of the adhesive to be carried out under certain conditions of pressure (applied to keep the parts to be assembled in close contact with each other) and temperature.
Method of verifying the suitability of gluing a panel or material or other wood-based composite. In general, the verification involves pre-treatments of the specimens that simulate the environmental conditions/stresses and consequent moisture variations that the product will undergo after installation in well-defined situations of exposure. The result is expressed in terms of resistance values (for example in tensile shear) and/or cohesive failure through the visual evaluation of the percentage of residual wood fibers on the delamination surface of the specimens.
Structural efficiency of adhesives used between wood pieces when subjected to stress.
Strength value achieved by a specimen subjected to a certain stress (generally tensile shear) in order to determine the bonding quality.
The surface determined by the adhesive layer that joins two contiguous sheets of wood or a multilaminar wood board.
Juxtaposition of decorative sheared veneers obtained by opening the pack of veneers, that came out in order from the slicer, like the pages of a book. In this way, the figure on two successive veneers will give one a mirror image of the other.
Pair of areolate pit of adjacent cells.
Gap (tunnel) caused by the action of wood-degrading insects.
Wood species Scientific name: Pinus leucodermis Ant.
Insects that infest partially seasoned and seasoned wood of starch-rich Hardwoods. The attack is usually limited to sapwood but in undifferentiated heartwood may affect the entire cross-section of the trunk. The type of attack is similar to that caused by lyctids.
The polished surface, usually made of metal, from which workpieces are guided towards the cutting part of a woodworking machine.
Truss element subjected to tensile stress.
In a pallet, deck that redistributes the supported load to the ground.
Procedure whereby an impregnating agent in an aqueous solution is penetrated by hydrostatic pressure through the bottom of recently felled logs with bark.
Unedged sawn timber resulting from longitudinal sawing with successive parallel cuts. They are arranged on top of each other (excluding slabs) to reconstitute the shape of the log.
Set of unedged timbers obtained from a log by successive parallel longitudinal cuts and then arranged back on top of each other (usually by interposing laths between the boards) in the original order. Note: European practice in the trade of fine timbers such as oak, cypress, and tropical wood.
Process in which wood is heated under vacuum in creosote (tar oil) so that the water contained within evaporates. It is applied to undried or partially dried wood before pressure impregnation.
Moisture closely associated with the wood cell wall through molecular adsorption.
Water that permeates the cell walls and is bound to them.
Deformation of a semi-finished product that occurs lengthwise and perpendicular to its face. In the case of a sawn timber, it is generally due to the presence of reaction wood on one of its faces; in the case of plywood, it may be caused by an unbalanced panel composition (different symmetrical layers in terms of thickness, wood species or internal tensions).
Particular type of container or packaging.
A tool for supporting the skyline and allowing the carriage to pass through.
A beam made of structural timber and wood panels in the form of a long hollow box that bears a greater load on an opening than the individual elements. The top and bottom of the beam are made of wooden elements, while the sides are made of panels.
Pallet equipped with at least three vertical sides for holding the load.
Stacking of boards or other sawn wood of different lengths so that the stack is rectangular parallelepiped shape with flat faces.
Pith present but not visible on any face or edge.
A pneumatically or hydraulically operated braking device that allows the towing vehicle (tractor) and towed vehicle (trailer) to be braked simultaneously.
Primary subdivision of the stem which carries the photosynthetic and reproductive organs.
Area of the stem where many branches or nodes fit at the same height.
Part of the stem on which several branches (or knots) are at approximately the same height.
Two flattened or flat knots appearing on the same face of a sawn timber. They start from approximately the same point.
A condition whereby some specimens or woods appear relatively low in impact strength and, when stressed in bending, break sharply and not jaggedly.
Wood species Scientific name: Dalbergia nigra Fr. All. Origin: Eastern Brazil.
Limiting bend radius at which a timber or plywood can be bent without breaking.
See “Modulus Of Rupture (MOR)”.
Parquet consisting of strips of equal size, in which the butt joints occur at the centre of adjacent elements.
Biofuel obtained from pulverized and compressed biomass, with or without the use of pressing additives. It is in the form of cubic or cylindrical units. The raw material used for the production of briquettes can be woody biomass, herbaceous biomass, biomass derived from fruits, or a combination and mixture of different types of biomass.
Veneer that is too dry as a result of being stored in too dry conditions. It is a characteristic of certain wood species or of veneers that are too thin.
Wood characterized by abnormal fragility mostly localized in the core zone. It occurs in some tropical wood species.
Separation between contiguous growth rings or between woody portions of different densities within the same ring. It is often visible on the surface of a semi-finished product.
Biological alteration limited to the heartwood that can occur in standing Oak plants. In the early stage it is characterized by brownish flaming.
Fungal alteration of wood caused by basidiomycetes. Residual wood takes on a dark coloration, is crumbly to the touch, and shows regular surface cracks. The enzymatic hydrolysis activity of the fungi responsible for the attack predominantly affects the cellulosic component and associated carbohydrates of the cell wall resulting in structural type damage. This damage leaves a residue (mainly ligninic in nature) with color ranging from light to dark brown and, as a result of which, there is a brittle type of wood breakage that develops along rectangular planes. In cases of strong attack, the wood is cracked longitudinally and transversely, and at this stage the rot is referred to as “cubic.”
Attack, of uncertain etiology, on standing plant. It occurs with blackish spots on the bark.
Brownish flamed pattern appearing after felling.
Treatment in which preservative is applied to the surface of wood by employing a brush.
Procedure for a surface treatment in which the impregnating agent is applied to the wood using a brush.
Wood species Scientific name: Guibourtia sp.p. (G. demensii) ATIBT nomenclature: Bubinga. Origin: West Africa.
Localized swelling on the curved surface of round wood. Note: Its presence may indicate a covered knot, foreign bodies, etc.