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Demidovo Plywood :: Terminology

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Terminology

Balanced plywood

- Plywood in which the outer and inner layers are symmetrical about the center layer with respect to thickness and species.

Blockboard

- Core plywood, the core of which is made of strips of solid wood more than 7mm wide but not wider than 30mm, which may or may not be glued together.

Cement-bonded Particleboard

- Wood-based panel material (as defined in BS EN 633) manufactured under pressure, based on wood or other vegetable particles bound with hydraulic cement and possibly containing additives.

Composite plywood

Plywood, the core (or certain layers) of which are made of materials other than solid wood or veneers. There are at least two crossbanded layers on each side of the core.

Core

- Central layer visible on the edges of the manufactured panel, generally thicker than the other layers and consisting of:
  • Blocks or strips of wood placed side by side which may or may not be glued together;
  • Other wood-based material;
  • Other sheet material;
  • Cellular construction;

Core plywood

- Plywood having a core.

Dry conditions

- Conditions corresponding to service class 1 of DD ENV 1995-1-1 which is characterized by a moisture content in the material corresponding to a temperature of 20°C and a relative humidity of the surrounding air only exceeding 65% for a few weeks per year.

Dry Process Boards (MDF)

- Wood fibreboards having a fibre moisture content of less than 20% at the forming stage, and having a density of >=. 450kg/m3. These boards are essentially produced under heat and pressure with the addition of a synthetic adhesive. Note: for marketing purposes, MDF of specific density ranges can be given different denominations. For example, the following density-related marketing terms for MDF have become established:

  • HDF - MDF with a density of ≥ 800kg/m3
  • Light MDF - with a density of ≤ 650kg/m3
  • Ultra-light MDF - MDF with a density of ≤ 550kg/m3

Dry process fibreboards can be given additional properties, e.g. fire resistance, moisture resistance, resistance against biological attack, either by changing the composition of the synthetic adhesive or by the inclusion of other additives.


External conditions

- Conditions corresponding with service class 3 of DD ENV 1995-1-1 which is characterized by climatic conditions leading to higher moisture contents than in service class 2.

Hard boards

- (HB, density > 900kg/m3) They can be given additional properties, e.g. fire resistance, moisture resistance, resistance against biological attack, workability (e.g. mouldability), either by specific treatment (e.g. "tempering", "oil tempering") or by the addition of a synthetic adhesive or other additives.

Humid conditions

- Conditions corresponding with service class 2 of DD ENV 1995-1-41 which is characterized by a moisture content in the material corresponding to a temperature of 20°C and a relative humidity of the surrounding air only exceeding 85% for a few weeks per year.

Laminboard

- Core plywood, the core of which is made of strips of veneer not thicker than 7mm placed on edge, all or most of which are glued together.

Layer

- Either one ply or two or more plies, glued together with their grain direction parallel, or another material.

Length of a panel

- Conventionally, dimension at right angles to the width.

Longitudinal layer (centre)

- Inner layer having grain direction parallel to the outer layers.