The lumber is know ready for the drying process. The stacked lumber is placed into a kiln where heated air is circulated around the lumber removing moisture from it. Shavings from the planer mill are burned to produce the heat. Green lumber, as it is called before it is dried, is made up of about 50% water. In the drying process the moisture content is brought down to about 19%. This makes the wood not only lighter, but stronger as well. This also reduces the amount of shrinkage in the lumber after it is finished.