TYPES OF VENEER SLICING


Action of the slicing blade on the wet wood.

Leaf of ash veneer showing the "tight" and "loose" sides.

Log opened up showing the plain sliced character of the wood.

Counterfront showing "barber poling" or polarization.
Cell Polarization
When veneer is Book Matched, alternating sections are turned over like the pages of a book. This reverses the angle of the cells that appear on the face. Thus, cells that pickup light on one side, cast a shadow in adjoining faces.
There are three main types of veneer slicing equipment used commercially.
  1. A rotary lathe in which the wood is turned against a very sharp blade and peeled off in one continuous or semi-continuous roll;
  2. 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; or
  3. 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.
Each of these types of processes gives a very distinctive type of grain depending upon the species. In any of these veneer slicing methods, when the veneer is sliced a distortion of the grain occurs. The knife blade as it hits the wood creates a "loose" side where the cells have been opened up by the blade, and a "tight' side. In the figure to the right the tight and loose sides are indicated by the way in which the piece of veneer bends or cups. The coloring differentiations created by the tight and loose side should not be confused with the "barber poling" effect which takes place in certain wood in which the same piece of wood appears to be dark or light depending upon which way it is viewed. This is caused by polarization of the grain wherein the grain is slightly angled from the surface, and depending upon where the light source is coming from the grain is either in shadow or is penetrated by the light.
After veneer is sliced, the veneer passes through a veneer screen dryer to bring its moisture content down to approximately 8 - 12%. Upon exiting the dryer, bundles of veneer are made from sequences of veneer leaves. Bundles generally include 24 to 32 leaves.

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