The short answer is that the tree is felled, planked, cut to width, dried and then machined into flooring, but this hugely simplifies the process.
Firstly the tree is selected and then felled. Often the lower part of the tree is then separated from the upper part and it is this lower portion that is used for boards while the upper part is often used for beams.
The trunk is then taken to a saw mill who will then determine how best to plank it, getting the best possible yield from the tree. The most common way is “through and through”. This is where the tree is placed on a rack and is then passed through a large bandsaw which slices the wood in much the same way as a ham is sliced in a butcher or supermarket. Different ways of cutting a tree can be used to reveal different grain patterns, such as quarter sawn (when the tree is “quartered” and then each quarter is planked. This tends to reveal a straight grain)
When Oak is freshly felled, the moisture content is between 60% and 80%, however an Oak Floor needs to have a much lower moisture content of 10 – 12%. This reduction is achieved by drying the timber in two stages. The slices are stacked with sticks separating each board so allowing air to pass through the pile of timber and providing natural drying. Once much of the moisture has dissipated, the boards are then ready to be dried in a kiln.
Air drying is a slow process relative to kiln drying, however the more drying that is done by mother nature, the cheaper the process. By contrast, the longer that timber is left drying naturally, the greater the amount of money that is then tied up in stock. In part, this explains why different manufacturers choose to switch to kiln drying at slightly different moisture contents.
Some manufacturers will machine the slabs into parallel boards after the timber is air dried but before the kilning process, while others will machine the boards parallel after the timber has been kiln dried. The former usually ends up with boards that have slightly distorted in the drying process, while the latter guarantees that the boards are parallel.
Now that the boards are dry and more or less parallel, they can be machined into a finished floorboard. The machines that do this are large and expensive planers which have varying numbers of cutters. The number of planer cutters often determines the capacity of the machine. A small machine may have 4,5 or 6 planer “heads” while large machines can have many more.
These planer heads will machine all four sides of the board at once. With the very large machines each cutter will machine a small amount of material and there will be several cutters duplicating each cut thereby incrementally reducing the size. This often leads to a better finish.
Smaller machines will often (but not always) either have to accept a lesser quality, process the material twice or process the material more slowly. Some factories will have two or more machines in series with the first performing a rough cut and the second a finishing cut. The quality of the planer blades and the speed at which the planer blades rotate also have a bearing on the quality of finish.
Lastly the flooring then enters a machine called an “End Matcher”. This is specifically designed to square cut the end of the board and to cut the tongue and groove onto the ends.
The boards are then ready to be fitted and to transform your floor into a thing of beauty and warmth. Oak is a wonderfully tactile and durable material and is also very versatile in the settings which can accommodate it, everything from a 16th century thatched cottage to a modern minimalist apartment.
If you have an Oak Floor, appreciate and enjoy it and marvel at Mother Nature’s gift to us!
