What is Lumber?

Once the logs are cut from the standing tree, they must be cleaned and all other limbs removed, including limb stubs. During this process the logs are inspected for faults, such as knots, unwanted piece of metal embedded in the wood, or fungus. 

Debarking may be done with high-powered jets that remove the bark from felled trunks, or it may be accomplished by a mechanical ring debarker that uses a series of cutting blades rotated along the surface of the log. The bark is sometimes used for decorative mulch, but in most cases it's discarded. 

After a log is debarked, it is cut down into sizes appropriate for the finished product, based on the original size of the log. Larger pieces will go for plywood, where smaller, less healthy pieces will go for pulp. Buck saws handle the cutting of the large, unwieldy logs. Preparation is handled while the wood's still wet, and water may be sprayed over the logs many times to keep it from drying out.

The lengths of wood are measured and scanned for defects by optical sensors. Then, a computer maps out a series of cuts that would provide the most solid boards. The computer operator uses his judgment and experience to make a final decision on how the wood will be cut. A headrig saw cuts the boards lengthwise according to the operator's instructions. First, the curved pieces, called slabs, are cut from each piece of wood. These pieces are usually recycled as mulch or regarded as scrap. Then, the saw cuts the rest of the log into usable pieces.

Boards are not ready to be used until they are seasoned, planed and graded. Seasoning prevents rotting as the boards age. The wood will either be placed in a holding area over time or heated in a kiln, which draws more moisture out of the wood in a shorter period of time. Next, wood is sent through a planer to perfect the dimensions, smooth the surfaces and round the corners. Finally, machines and workers inspect the lumber and rate it based on the amount of defects present. Lumber of similar type and quality are packaged together and shipped to lumber yards for public sale.