Drying Wood
Drying wood is a necessary step when turning wood and must not be overlooked or disregarded if you want to make quality items that last for time; you will either need to dry the wood yourself or buy it dried from your supplier. Wood’s moisture can be measured with a moisture meter, a two-pronged device that reads moisture content in a percentage; they are around twenty dollars. A good moisture to make a finished product depends on your climate’s humidity levels; you do not want to have a moisture percentage in mind when drying, but rather wait for the moisture to stop changing and equalize with the surrounding environment. The purpose of drying wood is to prevent wood movement and cracking once made into a finished piece. Generally, a good moisture level for most environments is around 8%-15% moisture. Depending on what you are turning, there are many different options for drying wood to do it the quickest and with the best results. As you turn more and more, you will
If you are tuning a decent size bowl, it is very unlikely that the wood you are using is not fully dried. As a matter of fact, you do not want to use dry wood for bowl turning, because bowls require a lot of material to remove, and wet wood is much softer and easier to turn than dry, hardwood. Because of this, it is a good idea to “rough turn” bowls, and a few months later after drying, finish turn them. Rough turning bowls means turning them with thick walls and leaving the tenon on. As the bowl dries, it warps, and having thick walls gives enough material to reshape it into a round bowl when finished turning. Drying rough-turned bowls is a long and simple process. Put the rough-turned bowl into a paper bag or in a cool-ish area, and let it sit for a few months or until equalized to the environment. It is a good idea to check on the bowl frequently to inspect for mold or cracking. It is common practice to seal the end grain of the bowl with a sealant, like wax or “Anchorseal” paint. This slows down dry time which minimizes warpage and risk of cracking.
However, it is possible to buy dried wood. Some sawmills will kiln dry their slabs, but it is usually for only thin boards. Even if it is advertised as dried, I often find that it is not dried entirely, so you should still twice turn platters and such from slabs and simply let them dry/equalize for less time.
On the other hand, aside from letting your wood dry in a few months, you can speed up the process to just a couple of minutes with a microwave. Especially for turning bowls, a microwave is a good alternative if you are either in a rush or just making a couple of bowls. To do this, simply put your rough-turned bowl in the microwave for periods of one minute at a time, and after each minute, observe if the bowl is steaming or not. Eventually, after around 2-3 minutes, the bowl will no longer steam, and you know that the wood is dried. Do note that it is important to let the bowl cool down in between each microwave period. The microwave can also be used when once-turning bowls. This technique produces a thin bowl with a wavy rim due to warping when drying rapidly in the microwave. However, because of the warping, you must re-shape the base of the bowl to minimize the wobbling.
A far less common method of drying wood is not necessarily efficient and is only good for smaller pieces of wood. This method is osmotic drying, and to do this, you must soak the wet wood in very saline water for hours, and then let the water evaporate after removing the wood from the solution. This process removes water from the wood cells through the salt water’s hypotonic properties. The wood cells are trying to get rid of their water to create an equilibrium between the solute content of the water and the cell’s solute. This shrinks the cells, removing the water from within, yielding a dry piece of wood.
