Glossary

Particle Board / Plywood Glossary

B

Blockboard

Is core plywood, of which the core is made of strips of solid wood more than 7mm wide but not wider than 30 mm.

C

Composite Plywood

Is plywood, of which the core or certain layers are made out of materials other than solid wood or veneers.

Composition

Is the description of the constituent elements of plywood.

D

Decorative Plywood

Is used where the appearance is most important; paneling and furniture. Exterior plywood refers to the bonding quality; the adhesive used in exterior plywood is weather proof and the plywood can be used in exterior or humid conditions.

F

Face, Back

The better quality surface of plywood is called the face and the surface opposite to the face is the back.

Fiberboard

Is a type of engineered wood product that is made out of wood fibers. Types of fiberboard, in order of decreasing density include particle board, medium-density fiberboard, high-density fiberboard and hardboard. Fiberboard is sometimes used as a synonym for particleboard, but particleboard usually refers to low-density fiberboard. Plywood is not a type of fiberboard, as it is made of thin sheets of wood, not wood fibers or particles. Fiberboard, particularly medium-density fiberboard, is heavily used in the furniture industry.

Finished Plywood

Is plywood further processed by sanding or overlaying.

Fire Properties

As a wood product, plywood is classified as a combustible material. The ignition temperature is 270° C if exposed directly to a flame. If not, ignition does occur at a temperature of 400°C. However, the performance of plywood in the event of a fire is very high, as the surface of plywood is carbonized, which protects the panel and slows down the burning process.

H

Hardboard

Is also called high-density fiberboard and is a type of fiberboard which is an engineered wood product. It is similar to particleboard and medium-density fiberboard but is denser and much harder because it is made out of exploded wood fibers that have been highly compressed. It is referred to as “Masonite” in the USA because that was the first brand to be marketed here in the 1920’s, 25 years after it was invented in England.

Hardwood Plywood

Refers to plywood made out of hard wood tree species used, as beech, birch, Okoume etc. They can be mixed as well.

I

I-beam

A beam with an I or H-shaped cross section. The horizontal elements are flanges, while the vertical element is the web. The Euler-Bernoulli beam equation shows this is a very efficient form for carrying both bending and shears in the plane of the web. The cross-section has a reduced capacity in the transverse direction and is also inefficient in carrying torsion for which hollow structural sections are often preferred.

Interior Plywood

Is plywood that is intended for use inside.

L

Laminboard

Is core plywood, the core of which is made of strips of veneer, not thicker than 7mm, placed on edge.

Lay-up

Is the arrangement of layers in plywood.

Length of a Panel

The panel dimension is in the direction of the grain of the face and back.

Lumber or Timber

Is a term used to describe wood, either standing or that has been processed for use, from the time trees are felled to its end product as a material suitable for industrial use as a structural material for construction or wood pulp for paper production. In the US and Australia, “timber” is a term also used for sawn wood products (boards) whereas generally in the US and Canada, the product of timber cut into boards is referred to as lumber. In the US and Canada sawn wood products of 5” diameter or greater are sometimes called “timbers”.

M

Medium-Density Fiberboard (MDF)

An engineered wood product formed by breaking down softwood into wood fibers, often in a defibrator, combining it with was and resin and forming panels by applying high temperature and pressure. It is a building material similar in application to plywood but made up of separated fibers not wood veneers. It is denser than normal particleboard.

Moisture Properties

Plywood has in general a moisture content of 7 to 8% when it comes out of the factory. This might of course change due to the ambient atmosphere. However, the cross bonding of its different plies significantly reduces the dimensional changes of plywood.

O

Oriented Strand Board (OSB)

Is an engineered wood product formed by layering strands (flakes) of wood in specific orientations. In appearance it has a rough and variegated surface with the individual strips (1” x 6” each) lying unevenly across each other in the direction of their grain.

Overlaid Plywood

Is plywood surfaced with one or several overlay sheets or one or several films such as impregnated paper, plastic, resin film, metal or decorative veneer.

P

Particleboard (chipboard)

An engineered wood product manufactured from wood particles such as wood chips, sawmill shavings or even saw dust and a synthetic rein or other suitable binder which is pressed and extruded. Particle board is a type of fiberboard, a composite material, but it is made up of larger pieces of wood than medium-density fiberboard and hardboard.

Plywood

Is the first type of engineered wood to be invented. It is made from think sheets of wood veneer called “plies”. These are stacked together with the direction of each ply’s grain differing from its neighbors’ by 90° (crossbanding). The plies are bonded under heat and pressure with strong adhesives, usually phenol formaldehyde resin, making plywood a type of composite material. A common reason for using plywood instead of plain wood is its resistance to cracking, shrinkage, twisting/warping and its general high degree of strength.

Plywood Grades

Plywood is graded by the quality of the outer plies.

Plywood Quality Classification

Plywood is classified by visual appearance of face veneers. The face veneers of different grades do not cause differences in the strength and stiffness of the panels. The grade of face veneers in one plywood sheet may be different; ten the grade of better face is given first.

S

Softwood

A generic term used in woodworking and the lumber industry for wood from conifers (needle-bearing trees from the order Pinales). Softwood producing trees include pine, spruce, cedar, fir, larch, Douglass-fir, hemlock, cypress, redwood and yew.

Softwood Plywood

Plywood made out of soft wood tree species (maritime pine, spruce etc.) It refers in general to structural plywood.

Structural Plywood

Structural plywood is used in building construction for sheathing on walls and roofs and floor underlayment. So it is often not visible after the building is done. Most structural plywood is made from softwoods and uses thick, low-grade veneers. For certain uses, like siding and concrete forms, a better grade face veneer may be required.

V

Veneer

A thin sheet of wood not more than 7mm in thickness. Sliced veneer is produced by slicing and rotary cut veneer by peeling.

W

Width of a Panel

The panel dimension at right angle to the length.

Wood Pellets

Are a type of wood fuel, generally made from compacted sawdust. They are usually produced as a byproduct of sawmilling and other wood transformation activities. The pellets are extremely dense and can be produced with a low humidity content (below 10%) that allows them to be burned with very high combustion efficiency. Further, their regular geometry and small size allow automatic feeding with very fine calibration. They can be fed to a burner by auger feeding or by pneumatic conveying.