Environment
MDF has already made a major contribution to the more efficient utilisation of the worlds timber resources insofar as furniture materials are concerned. Taking account of the increasing use of standard grade MDF in different industries and the recent availability of speciality grades which will dramatically extend the range of application of MDF, this contribution is likely to increase in the future.
European MDF is manufactured largely from local grown timber. Softwood species such as maritime and Scots pine, spruce and fir are used predominantly but these may be mixed in varying proportions with hardwoods such as beech, birch, hornbeam, oak and poplar. Large volumes of small logs which are produced as part of a planned forestry operation are used together with any saw mill or other factory residues. Often, the logs are cut from plantations specifically arranged to provide raw materials for the timber using industries and now managed on a sustainable yield basis. Cleared areas are normally replanted to provide timber resources for the future.
Compared with the high wastage when using hardwoods for the manufacture of furniture, fitments and building components, MDF makes good use of the whole log. Sapwood and pith which are cut away from furniture timber, the large percentage of wood which is rejected because of irregular grain, knots or drying defects, and normal processing waste do not figure in MDF production. When processing hardwoods for solid wood furniture or building components, as much as half the available wood is wasted. By comparison, the only waste when processing logs for the manufacture of MDF is the bark, most of which is removed mechanically before converting the wood raw material into fibre. Even the bark can be used efficiently as a fuel for the generation of process energy.
Apart from this total log utilisation efficiency, MDF has an environmental benefit where it is used as a replacement for solid wood. This aspect of MDF use is considered to be of particular significance in relation to the current environmental concern with the increasing rate of tropical and other primary natural forest destruction. Although the solution to this world wide problem extends beyond the immediate activities of the timber industries, the need to use tropical hardwoods more efficiently for high added value applications has been demonstrated. Equally, the need to use all timber efficiently is becoming increasingly apparent.
In the furniture industry, the tradition of using a low value core material edged with decorative wood strips and surfaced with decorative veneer goes back many centuries. Before wood based sheet materials were available, the only core material was low grade solid wood. Without doubt, MDF is a superior core material both in respect of its smooth surfaces and its good dimensional stability in the changing environments of modern buildings. Furthermore, by making use of the well compacted edges of MDF which can be well machined and directly finished to a high quality appearance, a further saving can be made by omitting the solid wood edgings.
As a numerical example of the efficiency of substitution of environmentally sensitive timbers such as mahogany or rosewood, a consignment of 1000 solid wood table tops, each 2000 mm x 1000 mm x 25 mm would contain 50m3 of timber. Allowing for processing waste, the manufacturer would use approximately 100m3 of top quality timber to produce these tables. The same size tables constructed with an MDF core with 25 mm x 25 mm solid wood lippings on all four edges and 0.6 mm thickness decorative wood veneers on each face would contain approximately 6m3 of the decorative wood. Using an MDF core without solid wood lippings, the decorative wood content of the veneers alone would be about 2.5m3, a forty fold saving over the solid wood equivalent.
Referring to board production aspects, some conservation organisations have been concerned with the use of formaldehyde based resins for the manufacture of MDF and with local atmospheric pollution in the vicinity of the MDF factories. These concerns have very largely been dissapated by the substantial reduction in the formaldehyde content of MDF from about 100mg/100g of board in the early years of its development to not more than 8mg/100g for Class E1 MDF as specified in EN 622-1.
Local emissions, mainly of water vapour, are now strictly controlled by stringent National regulations concerned with environmental protection. MDF manufacturers have made considerable investments in pollution control equipment to satisfy these regulations.