Have you ever take a look at the plywood that is used for various types of construction and wondered just how it was made? In this article we are going to take a quick look at plywood and its components and find out exactly where it comes from.
The building blocks of plywood
Plywood, of course, does not come off the log in the way that you see it. Instead, it is made up of several different layers of thing strips of wood called veneer. The veneer is placed around a core of the very best wood off of a tree, with the strips of veneer placed on top. Both the core and the veneer are very thin pieces of wood, no more than a couple of millimetres thick. For the highest quality plywood, the core and the veneer must be free of defects such as knots and holes and so on.
What about the veneer?
The veneer itself is the first product off the log once a tree reaches the sawmill. Before machinery became common place, veneer was sawed off a log by hand. Today, there are a couple of different ways in which veneer is produced.
The pieces are peeled off of the trunk of the tree using fast working machines
Large rectangular blocks of wood are cut in order to make the veneer. These blocks are called flitches.
In addition, there are several different types of machine that are used to peel or slice the log into strips of veneer. Rotary lathes are known for producing the highest quality, plywood grade veneer, while flitches are cut using a slicing machine. A half round lathe might also be used to create the sheets of veneer.
Treating the veneer
The term “thin veneer of civilization” doesn’t exist for no reason; veneer is very thin indeed and must be treated with care. Usually cutting the veneer off of the trunk and processing the pieces take place at different mills; treating the veneer takes place at the same location where the plywood will be created.
The loads of veneer are shipped to the mill where they are dried, taking out all remaining sap and moisture. The veneer is then sorted into grades depending on quality. If there are replaceable knots or holes the veneer can be patched on site as well.
Once the veneer has been treated and sorted, it can be used to produce the different pieces and grades of plywood you will encounter in construction.
