Man-made Boards

Josh Ricketts says:

There are various types of man-made board. The main size of the board bought is 2440 mm by 1220 mm, and then the thickness is decided by the designer and/ or manufacturer, which can be made to order in steps of 3mm thickness, 3mm being the smallest. The types of man made board mainly used today are listed below and described.

Plywood - Is strong because of the layers of wood arranged in such a way that makes the board tough in both directions. The grain is aligned so that each layer counteracts the other and makes it strong, because of how wood is weak along the grain. Marine plywood, aptly named, has a plastic based layer coated onto the outside of the wood to make the wood more water resistant.

Medium Density Fibreboard (MDF) - Is made from wood chippings from the conversion process (mentioned in earlier post). These waste chips then have glue added to them and then pressure is applied to squash the bit together to create the finished product. High Density Fibreboard has had even more pressure applied to it and so therefore costs more. The hardened glue in MDF gives the board blunting properties and so in manufacture of large quantities, the cost efficiency of having broken or just blunt saws can be serious when dealing with thousands of products.

Hardboard - Or HDF (mentioned above), is mainly for filling gaps. The weak, brittle material is useless for products and is mainly used for the backs of furniture. Hardboard absorbs liquid easily and can hence become rotten and useless. As a result of this, hardboard is very cheap.

Chipboard - Is commonly used for kitchen worktops and units. Chipboard is made of bigger wood chippings and usually has a laminate or other attractive material on top to 'hide' the chipboard. Made in the same way as MDF, using chippings with glue then compressed.


Blockboard - Uses a different method to attain a good finish. Strips of cheap wood are stuck together is rows and then are sandwiched between two veneers. Its the veneers which make board worth something, as the veneers are attractive and the blocks are hidden.

Aero-ply - Is, as the name suggests, used in the structure of plane wings. The material is made in such as way that in bends around an object or frame, by having many separated blocks with a flexible top layer.

Maplex - Is a higher grade board for furniture which is new and easier to machine. High density and made of pure wood fibres, Maplex is expensive and acts and looks like sheet metal. This ultra modern material is used as shown to the left, to make a variety of high quality products.


Veneers

A veneer is basically a 'slice' of wood. Usually thinner than 3 mm, they are typically glued onto core panels to produce flat panels such as doors, tops and panels for cabinets, parquet floors and parts of furniture. To produce these veneers 3 main types of processes are used; Slice, Rotatory and '3D' Veneering.


Slice Veneering - Involves a piece of log that is raised and lowered against a blade and slices of the log are made. This yields veneer which looks like sawn pieces of wood, cut across the growth rings. This gives a decorative pattern for multiple uses and is cheap compared to the other methods.

Rotatory Veneering - Uses a rotary lathe in which the wood is turned against a very sharp blade and peeled off in one continuous or semi-continuous roll. Rotary-cut veneer is mainly used for plywood, as the appearance is not desirable because the veneer is cut concentric to the growth rings.

3D Veneering - Is a process in which a half-round lathe in which the log or piece of log can be turned and moved in such a way to expose the most interesting parts of the grain. This means you get the best results of veneer but waste material getting to the interesting grain.

Each slicing processes gives a very distinctive type of grain which is important for the aesthetic qualities the designer is looking for.


Finishing Wood

Wood protection is vital for any wooden product and come in both water and oil based composites.

Polyurethane Varnish - Seals and protects with a smooth finish. The plastic covers the wood like an extra layer and stops water and other chemicals getting to the wood. The varnish is usually uncoloured but still enhances the wood's natural colour and grain.

Wood Stains - May have a varnish with them, but if not then varnish must be added on top of stain. The stain colours the wood to many shades of brown and other colours like red and green.

Oils - Enhance the natural wood colours and protects the wood too. Oils can be for outdoors too, as the oil resists water molecules and therefore is perfect for outdoor use.

Preservatives - Are for outdoor use of wood. They enhance appearance and extend the wood's life by up to 5 times as long. This is extremely useful for long life wood products. Tanalised timber is a common timber product which is coloured green. The original timber is injected with tanalise so that 5mm into the wood is tanalised and the wood in protected greatly.

Paint - Is colouring and protecting. Emulsion paints have too much water in them and would warp the wood so special wood paints are used. Polyurethane paints are available for waterproofing and are tough at protecting but however, are more expensive.