HARDWOOD FLOORING 101
Hardwood flooring is manufactured from a variety of trees. In the USA, Oak flooring (red and white) are the most common species. Although other domestic species are growing in popularity. Other common species are, Hickory, Maple, Walnut, Ash, American Cherry, Birch and Yellow Pine. Exotic species are also available in an extremely wide variety, but the most common are, Brazilian Cherry, Cumaru, Tigerwood and Santo Mahogany.Every species brings different characteristics ranging from coloration, graining, stability (see exhibit 1) and hardness. The standard for testing hardness of hardwood is called the Janka Scale (see exhibit 2).
Trees are harvested, and logs are sawn into rough cut lumber using a variety of sawing techniques. The most common is plain sawn because it gives a greater yield than other sawing techniques. Each technique results in different appearances and also can impact the dimensional stability and overall performance of the final product.
Then the lumber is dried in a yard with sticks placed between layers to allow for better air circulation. Some mills will then move the lumber to a pre-drier which speeds up the drying process. The goal is to get the lumber down to an 18 -20% moisture content before going into the kiln. Wood to be made into hardwood flooring is then moved into a kiln where it is dried to a 6 – 8% moisture content. This is a closely measured and monitored process. It is done slowly to avoid checking and other wood drying problems. The kiln drying process also kills any insects still living in the wood. Once the lumber reaches the desired moisture content it is milled into flooring.