Wood Veneer

In woodworking, veneer refers to thin slices of wood and sometimes bark, usually thinner than 3 mm (1/8 inch), that typically are glued onto core panels (typically, wood, particle board or medium-density fiberboard) to produce flat panels such as doors, tops and panels for cabinets, parquet floors and parts of furniture. They are also used in marquetry. Plywood consists of three or more layers of veneer. Normally, each is glued with its grain at right angles to adjacent layers for strength. Veneer beading is a thin layer of decorative edging placed around objects, such as jewelry boxes. Veneer is also used to replace decorative papers in Wood Veneer HPL.

Background

Veneer is obtained either by "peeling" the trunk of a tree or by slicing large rectangular blocks of wood known as flitches. The appearance of the grain and figure in wood comes from slicing through the growth rings of a tree and depends upon the angle at which the wood is sliced. There are three main types of veneer-making equipment used commercially:
* 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.
* A slicing machine in which the flitch or piece of log is raised and lowered against the blade and slices of the log are made. This yields veneer that looks like sawn pieces of wood, cut across the growth rings; such veneer is referred to as "crown cut".
* A half-round lathe in which the log or piece of log can be turned and moved in such a way as to expose the most interesting parts of the grain, creating a more textured feel and appearance; such veneer is commonly referred to as "rift cut".

Each slicing processes gives a very distinctive type of grain, depending upon the tree species. In any of the veneer-slicing methods, when the veneer is sliced, a distortion of the grain occurs. As it hits the wood, the knife blade creates a "loose" side where the cells have been opened up by the blade, and a "tight" side.

Historically veneers were also sawn, but this is more wasteful of wood. Veneering is an ancient art, dating back to at least the ancient Egyptians who used expensive and rare wood veneers over cheaper timbers to produce their furniture and sarcophagi. During the Roman Empire, Romans also used veneered work in mass quantities.

Producing wood veneers

The finest and rarest logs are sent to companies that produce veneer. The advantage to this practice is twofold. First, it provides the most financial gain to the owner of the log. Secondly, and of more importance to the woodworker, it greatly expands the amount of usable wood. While a log used for solid lumber is cut into thick pieces, usually no thinner than 1/8 of an inch (3 mm), veneers are cut as thin as 1/40 of an inch (0.6 mm). Depending on the cutting process used by the veneer manufacturer, very little wood is wasted by the saw blade thickness, known as the saw kerf. Accordingly, the yield of a rare grain pattern or wood type is greatly increased, in turn placing less stress on the resource. Some manufacturers even use a very wide knife to "slice off" the thin veneer pieces. In this way, none of the wood is wasted. The slices of veneer are always kept in the order in which they are cut from the log and are often sold this way.

Types of veneers

There are a few types of veneers available, each serving a particular purpose.
* Raw veneer has no backing on it and can be used with either side facing up. It is important to note that the two sides will appear different when a finish has been applied, due to the cell structure of the wood.
* Paper backed veneer is as the name suggests, veneers that are backed with paper. The advantage to this is it is available in large sizes, or sheets, as smaller pieces are joined prior to adding the backing. This is helpful for users that do not wish to join smaller pieces of raw veneers together. This is also helpful when veneering curves and columns as the veneer is less likely to crack.
* Phenolic backed veneer is less common and is used for composite, or artificial wood veneers. Due to concern for the natural resource, this is becoming more popular. It too has the advantage of being available in sheets, and is also less likely to crack when being used on curves.
* Laid up veneer is raw veneer that has been joined to make larger pieces. The process is time-consuming and requires great care, but is not difficult and requires no expensive tools or machinery. Veneers can be ordered through some companies already laid up to any size, shape or design.
* Reconstituted veneer is made from fast-growing tropical species. Raw veneer is cut from a log, and dyed if necessary. Once dyed, the sheets are laminated together to form a block. The block is then sliced so that the edges of the laminated veneer become the “grain” of the reconstituted veneer.
* Wood on Wood Also called 2-ply is a decorative wood veneer face with a utility grade wood backer applied at an opposing direction to the face veneer.

Advantages of using veneers

Compared to wood, one of the primary advantages of using veneer is stability. While solid wood can be prone to warping and splitting, because veneer is made of thin layers of wood glued together, the chances of splitting or cracking are reduced.

Some projects built using wood veneer would not be possible to construct using solid lumber, owing to expansion and contraction caused by fluctuation of temperature and humidity. Another advantage of veneer is sustainability—furniture made with wood veneer uses less wood than the same piece of furniture made with solid wood. Further, veneer may also be more readily available than solid wood as exotic hardwood lumber can be scarce and very expensive.

Ecological characteristics

* Recyclability and renewability: Wood has the least impact on total energy use, greenhouse gases, air and water pollution, solid waste and ecological resource use. Seventy percent less energy is required in the use of wood compared with any other building materials.
* Sustainability: Using veneer extends the use of a piece of timber. The wood that might be used in one solid piece a few visible cm wide can cover a far greater area when used as a veneer.
* Toxicity: Many veneers are non-toxic, though veneers made of woods like bubinga and wengé are toxic, and appropriate precautions should be taken to avoid health problems from dust inhalation, splinters and the like.
* Veneer stores carbon and also maximises the use of harvested wood.

Buying veneers

Wood veneers are typically sold by the square foot. With the ability to join veneers, even small pieces are usable, resulting in very little waste.
Many sources sell small packets of veneers that are sequence matched and are ideal for small projects. These make experimenting and practicing much more economical. It is also possible to buy plywood and other substrates with veneered faces for larger projects consisting of casework.

See also

* Plywood
* Multilaminar veneer
* Veneer hammer
* Engineered wood
* Bookmatching

References

Benson, Jonathan
''Woodworker's Guide to Veneering and Inlay'', Fox Chapel Publishing

External links

European Panel Federation

Decorative Wood Veneers Association
Information on species, matching techniques and specifying of wood veneer.

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Timber preparation
Woodworking materials
Wood products
Surface decorative techniques in woodworking
Composite materials