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American hardwood veneer

This section provides information on the American hardwood veneer industry, the production process, species availability, export grades and details of the relevant product association in the USA.

Veneer is a thin layer of wood of uniform thickness produced by peeling logs or slicing flitches.

HARDWOOD VENEER INDUSTRY

The veneer industry has a long tradition of technical advance, which today enables it to produce high quality, sliced and rotary cut veneer for furniture, panelling, doors and panel products. There are approximately 35 veneer slicing facilities in the USA, operating nearly 100 slicers in total and 32 half-round slicers. Many lengthwise slicers and approximately 50 rotary lathes are operated by 35 additional companies. Total sliced production is nearly 669 million square metres annually, with exports representing 354 million square metres – 53% of total production.

PRODUCTION

Different methods of veneer manufacture

Different slicing methods are used to produce different visual effects. Logs of a given species, cut by different methods will produce a variety of appearances.

Rotary cut:

In rotary cutting, the log is mounted centrally in the lathe and turned against a knife, as if unwinding a roll of paper. A multi-patterned grain marking is produced with this method. Rotary cut veneer can be sufficiently wide to provide full sheet (one piece) faces.

Flat slicing:

Flat cut, flat sliced, crown cut or plain sliced are synonymous terms used in different countries. The half log (flitch) is mounted with the heart side away from the knife against the flitch table of the slicer. The slicing is done parallel to a line through the centre of the log. This produces a distinctive “cathedral”, or heart figure. The ratio of quartered to crown faces produced by this method naturally runs about 60-40% in favour of crown.

The width of the veneer sheet depends on the size and species of the log. The oaks can produce widths in excess of 410mm, however requirements for specific sized logs should be pre-arranged between buyer and seller. Plain slicing produces the largest width veneer of the slicing methods as a log is cut into two flitches before slicing. The other slicing methods use logs which have been cut into several flitches prior to slicing.

Quarter slicing:

Quarter slicing involves first cutting the log into four pieces. Then the manufacturer places the quarter log (flitch) on the flitch table so that the growth rings of the log strike the knife at approximately right angles, producing a series of stripes, straight in some species, varied in others. The width of veneer produced through quarter slicing is less than plain slicing, with an average less than 200mm – depending on log size. The “flake” appearance in oak is produced by the quarter slicing method.

Half-round slicing:

Veneer is sliced on an arc roughly parallel to the centre of the log to achieve a flat cut appearance.  The “cathedral” pattern can have more rounded tops than the pattern produced by flat slicing.

Rift-cutting:

Rift-cut veneer is produced from the various species of oaks. The logs are cut into four pieces.

Rift-cut veneer has a straight grained look, which is obtained by periodically changing the cutting angle to stay about 15 degrees off the quartered position to avoid the “flake” figure. The width of veneer produced through rift-cutting is less than plain slicing, with an average less than 200mm – depending on log size.

Lengthwise slicing:

A board of flat sawn lumber is passed flat over a stationary knife. As it passes, a sheet of veneer is sliced from the bottom of the board. The width of the veneer and figure produced with this method depends on the width and figure of the sawn lumber and is typically variegated.

Veneer thickness and moisture content

A log or “flitch” can be cut to produce whatever thickness of veneer is required. However, in reality, the American industry has two main production thicknesses, as detailed in the Hardwood Plywood & Veneer Association's “Voluntary Standard for Sliced Decorative Wood Face Veneer – Industry Standard DFV-1 1995”. The thickness for most species in the domestic market is 0.65mm, and 0.55mm for export with the exception of cherry and walnut which is 0.50mm. Any requirement that is more specific than the details in the Standard requires special arrangements between buyer and seller. Special cuts are available; for example, 1.2mm thick rotary veneer is produced in some species for the American market for the production of engineered hardwood flooring.

Freshly sliced or peeled veneers are passed through continuous press dryers on moving belts, the speed of which is varied according to the species and thickness of the veneer. The moisture content standard for export veneer is 12-16%. This allows for the natural drying of veneer that occurs during shipment. Most veneer users allow the veneer to remain in their facilities for a few days before manufacturing. This delay allows for the wood’s natural conditioning in that specific environment as equilibrium moisture conditions in the USA and export markets such as Europe tend to vary.

Veneer grading

A specific industry-wide grading system does not exist for veneer: it is not sold as a commodity on the open market, but according to the requirements established by individual customers. Veneer is sold based on personal inspection or a clear understanding of grade between buyer and seller. Length, width, thickness, quantity, and other factors that affect yield and price, form the basis of this buyer-seller understanding.

The length of the log will establish whether the manufacturer will market the veneer for furniture, doors, panelling, or architectural applications. Width will also vary according to the intended end use, with the minimum width of veneer usually 90mm or 100mm.

Door and panel:

Top grades used for joinery, such as architectural panels and doors, with a minimum requirement in length for doors of 2.1m and panels of 2.5m. Within a typical panel or door grade there may well be many other sub-grades selected according to colour and grain pattern.

Furniture:

For furniture grades, length is not so critical and will typically run from 0.45m to 2.0m. There are fewer restrictions regarding natural characteristics, such as colour and grain pattern.

Falling bundle: 

The term “falling bundle” refers to a pallet or group of veneer consisting of single or odd bundles. The grade of the veneer in this grouping will likely express a wide variety of colour, character and grain variations.

The final price of hardwood veneer is determined by the natural limitations of what the forest can produce combined with the market demand. In addition, size and grade considerations weigh heavily on the final price. Only a small percentage of logs in a forest produce the top grades of veneer in terms of lengths, widths and natural characteristics. Special handling or shipping requirements and specific requests relating to length, width and/or thickness can also add to the final price.

Preparation and packaging of veneer for export markets

In addition to the difference in thickness, veneer for export is prepared differently from veneer produced for the domestic market. It is “clipped and bundled” or “export prepared”. The edges are trimmed on the sides and ends and sheets are tied in bundles. This extra manufacturing process helps improve presentation and assists in defining grades, whereas domestic veneer is left untrimmed.

The number of sheets in a bundle depends on the thickness, with 24 or 32 sheets per bundle standard for most species and thicknesses (0.4mm-0.6mm). The bundles from the flitch are usually kept and sold together, although on occasion they may be separated and regrouped with other flitches for specific customers.

EXPORT AVAILABILITY

In reality most commercial American hardwood species can be sliced or rotary cut to produce veneers. Therefore demand plays an important role in availability. The table below indicates veneer availability for the main commercial American hardwoods. This information is cross-referenced with the AHEC publication "Species".

Other available species

In some species certain logs occasionally produce dramatic grain patterns when specially sliced. Examples of some of these unusual figured veneers include walnut and oak burl, quilted maple and aspen, bird’s-eye maple, vavona (redwood burl) and madronna. Availability of these specially figured veneers will be limited as only a relatively small number of logs processed will have the necessary grain pattern.

EXPORT DISTRIBUTION

American hardwood veneer exporters distribute their product in export markets, through specialised importers and distributors. These companies typically hold stock in a wide range of species and grades in order to respond to user demand by inspection.

Significant volumes of hardwood veneers are sold to sheet material manufacturers, who then lay them on a range of substrates, such as medium density fibreboard (MDF) or particleboard. These panel products are then distributed to manufacturers and end users as decorative panels. It is important to note that under American terminology, these products are grouped together and known as hardwood plywood.