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To properly use wood for construction and for making furniture, you must properly dry it. The most common and the simplest process to dry wood is to let it passively sit at a given humidity level to obtain a desired level of dryness.
However, this can take a lot of time anywhere from months to years. Wood drying time can vary significantly according to wood species, initial moisture level, the thickness of the wood, density, ambient conditions, and the drying technique that you wish to use.
Drying times and kilns
For a quick answer, it can take about a year for wood to completely dry. As a general rule, you must allow at least one year of drying time per inch of wood thickness. Therefore if you want to dry a large piece of lumber then you are in for a very long, long, long time if you want to naturally season wood. If you simply don’t have time to wait, then there are some easy and faster ways to completely dry wood.
A kiln is frequently used to enhance the drying process. There are various types of kilns used to dry lumber but the design is the same. There is a large insulated chamber or room to balance and control humidity, temperature, and airflow to safely and efficiently reduce moisture and dry wood completely.
Kilns dry wood much more evenly, minimizing any of moisture gradients between the outer shell and the inner core. Thus, a kiln dries wood quickly and avoids the drying defects usually associated with rapid and uneven drying.
Although kilns are efficient in drying or seasoning wood, this can introduce internal stresses into the wood especially when an improper kiln schedule is followed or if special corrective measures are not used.
Case hardening is a defect that happens when the outer shell begins to dry faster than the core. The shell starts to shrink but the core remains wet.
If the moisture difference between the core and the shell is high then the shell can dry in a stretched manner. In extreme instances of case-hardening, the core can split to start honeycombing. This is an irreversible condition.
Drying your wood at home
Not all homes have kilns or special equipment to dry wood. If you want to dry wood at home then these techniques can save you time and effort.
1) Process logs at once.
If a storm has felled a tree or a tree was recently cut then you must not waste time. Process it by cutting and stacking. Doing this fast will help open up the wood and help stimulate the drying process which can prevent rot or staining.
2) Cut the wood in oversized sizes.
Wood shrinks as it dries, therefore, you must cut larger than the desired finished size.
3) Seal the ends of the logs.
This will prevent the wood from drying too quickly and to avoid splits and endgrain checking. Take note that moisture escapes from wood about 10 to 12 times faster on the ends compared to the body of the wood. Sealing the endgrain will keep the moisture in longer and forces it to exit in a slower, even manner.
4) Stack wood and use a sticker.
When lumber has uniform lengths and thicknesses this simplifies stacking. Once a log is sawn up into planks of ideal dimensions, you must stack these in such a way that these will be exposed to air from all its sides and surfaces. You must use stickers for such a task. The sticker is a term used for small pieces of wood (usually about 3/4” x 11/2”) that add space between sawn planks. Stickers increase ventilation and help in a more uniform drying process.
5) Add weight to your stacked wood.
Once the stack of wood is properly stacked and stickered, you must add weight to the stack. The wood found at the bottom of the stack is most likely weighed down by the wood on top of it, but boards found at the top greatly benefits from the added weight. Weighing the stack of wood down prevent warping or distortion.
There is no specific answer to how long does it take for wood to dry because there are many factors that can affect the rate of drying. The type of wood, size of the specimen, the local temperature, humidity, and temperature, as well as the drying technique to be used all affect drying times.