In order to answer what makes a log a veneer grade log, let’s first define what veneer is. Most people understand what lumber is (logs that are sawn into boards which are generally 1 or 2 inches thick and 4 to 10 inches wide). Veneer on the other hand is produced when logs are put on a lathe and long continuous sheets of wood are peeled off. These sheets of wood are generally around 1/42 of an inch thick for hardwood. Plywood (which you see sold at retail lumber yards) is actually sheets of veneer glued together. Hardwood doors and furniture are generally made from veneer.
Now we will get to the question. Defects are what determine whether or not a log is graded as a veneer log. Knots is one form of defect. A knot is created when limbs prune off and the tree grows additional wood over the area. Knots can fall out of the sheets of veneer during production and they can be a visual deformity. Seams are a major defect, which cause the sheets of veneer to break and come apart. Other defects include bird peck, gum, ring shake, insect damage, color and mineral. Another criteria for veneer logs is diameter and length. Logs that are too small or logs that are too big in diameter affect grade and quality. Logs that are 12 inches in diameter or larger is a common size that is utilized in veneer mills. Logs that are over 30 inches in diameter are generally not desirable because there are limitations to the size of logs that a lathe can handle.
There are many grades in veneer logs and acceptable defects affect the quality and value of the veneer and consequently the value of the logs.
This picture to the left shows the cut end of a hard maple log. To improve the quality of this veneer log a 4 inch thick piece was cut from the end of the log (the piece on the ground). When you look at the bottom slab the area circled with the red line shows an old scar. By cutting that off the quality of the log was improved. This log has what is called a small heart which is the darker colored center. In maple the light colored wood is what is valued.
This maple log to the right shows the effects of bird peck. When the birds wound the tree, bacteria feed on the sap and turns the wounded area a dark color. As sheets of veneer are peeled off this log there will be the dark color areas in the sheets and small holes from where the bird was pecking. Some of this wood will be used in the interior layers of the veneer panel.
The log below is an example of a high quality veneer log. The positive characteristics are a small heart, good diameter (16 to 17 inches) and surface free of defects. A good forest manager understands quality and by cutting poor quality trees and concentrating growth on your best trees creates logs like this one. It’s worth noting, when a tree reaches this quality, if you leave it stand too long your risk of degrade increases.
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