A wood veneer is a thin slice of wood cut as thin as 1/40 of
an inch and is used for gluing onto other wood, particle board or MDF
producing
flat panels for doors, tops and panels for cabinets, parquet floors,
parts of
furniture, edge banding and marquetry.
Veneers are obtained by turning the trunk of a tree against
a sharp blade on a rotary lathe producing a continuous or
semi-continuous roll.
Rotary-cut veneer is mainly used for plywood. Alternatively, high
quality
veneers are made by slicing large rectangular blocks of wood known as
flitches.
This slicing method gives a more beautiful cut of the grain and
provides a
broader use of the veneer. In either of the veneer producing methods, 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.
Veneers
are of several types;
- Raw veneer has no backing on it and
can
be used with either side 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 as well as the loose and tight sides created by the slicing.
- Paper Backed veneer is backed with a
paper. The advantage is that it is available in larger sizes than the
leaves
from a flitch. Smaller pieces are joined together prior to adding the
backing.
- Phenolic Backed veneer is less
common
and is used for composite, or man made 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, which
has
been joined together to make larger pieces. The process is time
consuming and
requires great care, but is not difficult.
Veneers
can be laid up by:
- Book
Matched -
where the veneers are opened from the flitch much like the pages of a
book.
- Slip
Matched -
where the pieces are joined together in the order they come from the
flitch,
and have the same face kept up.
- Radial
Matched -
where the veneer is cut into wedge shaped pieces and joined together.
- Diamond
Matched -
where the pattern formed is diamond shaped.
The preferred method for gluing
veneer onto the substrate is by using a vacuum press, where
glue is placed on the plywood and the veneer is set
on top. The panel is then placed inside a bag and the air from within
the bag is
removed with a vacuum system. A vacuum press is capable of producing
over 1700
pounds per square foot of pressure at full capacity, giving uniform
pressure on
the veneer and the substrate.
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