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Fibreboard is most often manufactured from wood chips which have been mechanically defibred (defibrated) or steam exploded or from other defibred ligno-cellulosic material (obtained e.g., from bagasse or bamboo). The fibres making up the board are recognisable under microscopic examination. They are bonded together in the board by felting and by their own adhesive properties, generally deriving from their lignin content. Additional resins or other organic bonding substances may be used to agglomerate the fibres. Impregnating or other agents may also be added during or after manufacture of the board to give an extra property, e.g., impermeability to water or resistance to rot, insect attack, fire or the spread of flame. Fibreboard may consist of a single sheet or of several sheets bonded together.
The categories of fibreboard of this heading can be distinguished according to their production process and they include :(A) Fibreboard obtained by the "dry production process"
This group includes, in particular, medium density fibreboard (MDF), which is manufactured in a process in which additional thermosetting resins are added to the dried wood fibres in order to assist the bonding process in the press. The density generally ranges from 0.45 g/cm³ to 1 g/cm³. In the unworked state it has two smooth surfaces. It can be used in many different applications such as furniture, interior decoration and in building.
Medium density fibreboard of a densityexceeding 0.8 g/cm³ is sometimes also referred to by the trade as "high density fibreboard (HDF)". (B) Fibreboard obtained by the "wet production process"
This group includes the following types of fibreboard : (1) Hardboard, which is manufactured in a wet production process in which the wood fibres in suspension in water are compressed in the form of a mat under high temperature and high pressure on a metallic mesh. In the unworked state this type of fibreboard has one smooth and one rough surface with a mesh pattern. However, it can sometimes also have two smooth surfaces obtained by special surface treatment or a special production process. It generally has a density exceeding 0.8 g/cm³. Hardboard is mainly used for furniture, in the automotive industries, for doorskins and for packaging, especially fruit and vegetable packaging. (2) Mediumboard, which is manufactured in a way similar to the one for hardboard but at a lower pressure. It generally has a density exceeding 0.35 g/cm³ but not exceeding 0.8 g/cm³. The main application is in furniture production and for interior or exterior walls. (3) Softboard. This fibreboard is not compressed as the other types of fibreboard obtained by the wet production process. It generally has a density of 0.35 g/cm³ or less. These boards are used mainly for thermal or sound insulation in building. Special types of insulating board are used as sheathing or sarking materials.
The products of this heading remain classified herein whether or not they have been worked to form the shapes provided for in respect of the goods of heading 44.09, curved, corrugated, perforated, cut or formed to shapes other than square or rectangular and whether or not they have been worked at the surface, the edge or the end, or coated or covered (e.g., with textile fabric, plastics, paint, paper or metal) or submitted to any other operation, provided these operations do not thereby give such products the essential character of articles of other headings. The heading does not cover : (a) Particle board whether or not laminated with one or several fibreboards (heading 44.10). (b) Laminated wood with a core consisting of fibreboard (heading 44.12). (c) Cellular wood panels of which both faces are fibreboard (heading 44.18). (d) Paperboard, such as multiplex paperboard, ≪ presspan ≫ and strawboard, which can generally be distinguished from fibreboard by their layer structure made apparent on cleaving (Chapter 48). (e) Fibreboard panels clearly identifiable as parts of furniture (generally Chapter 94).
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