Allowing lumber to passively sit at a given humidity level in order to obtain a desired EMC (air-drying) may be the simplest and least expensive method of seasoning wood, but it is also the very slowest. Editor’s note: The degree of wetness in wood is called moisture content, and it’s expressed as a percentage. Loss or gain of moisture in wood products may cause such troublesome results as shrinking or swelling, interference with paint adhesion, and increased susceptibility to decay and stain. The shrinking and swelling of wood are dimensional changes caused by loss or gain of water. In the wood products industry, the working unit is 1,000 board feet,” abbreviated mbf.
A selection of sizes from three to six inches in diameter for wood stoves and an inch or so larger for furnaces will probably serve you well. In the field of chemical modification of wood and wood products, the material should be dried to a certain moisture content for the appropriate reactions to occur. With this knowledge, you can now use all of the wood that you have accumulated, and have been waiting to use. Dimensions of the piece just before oven drying were 177 mm wide by 21.5 mm thick.
I have to check this project out, like the idea of taking a wood project all the way from start to finish. As the wood dries, it shrinks and the stack settles, losing 20 percent of its height. I understand different woods age at different rates and the chosen drying process itself is a factor. For example, floorboards and other thin pieces of wood might not be thick enough to get reliable readings from a pinless meter, whereas big lengths of lumber would be perfect for pinless moisture meters. If you look closely at the wood in bright, direct light, you should not be able to detect any dry spots.
For lumber such as thick red oak that is difficult to dry without causing seasoning checks, several additional steps may be necessary. Build in as much air as you can, using irregularities and odd-shaped logs to create cross-stack channels for drying air. Each piece spends about a month in a specially designed dehumidification kiln where the moisture level of the wood drops to between 6%-8%. Typically that means cutting and splitting the wood into manageable pieces and then air drying for the spring and summer. Wood exposed to air with a RH of about 90% will reach a Wood Moisture Content of about 20%.
Pin-type meters, in particular, have the advantage of being able to tell you the depth at which a moisture pocket in wood occurs. But that percentage often can exceed 100 because it represents the ratio of the weight of the water in a piece of wood to the weight of the same wood when it is completely dry. So ask your service providers a lot of questions and have them explain to you how their drying processes work. A variety of vacuum technologies exist, varying primarily in the method heat is introduced into the wood charge.
The powder form is generally less expensive but there’s some evidence that glycol improves the absorption of borate into the wood fibers. This defect is caused when the outer shell begins to dry faster than the core: the shell tries to shrink, but is inhibited by the still-wet core. Place the board in a cool, dry space without heating or air conditioning, such as a garage or shed. The viscosity of Gorilla Wood Glue will allow it to be injected using a glue syringe applicator. Note that clamping time can be dependent on temperature, humidity, and the porosity of the wood. Certain controls can be used in this stage of drying to make it more efficient.
Enclosing the carving in a bag gives moisture deep inside the wood time to migrate toward the drier outside. I’d guess that in all but a few select circumstances you’d end up with more usable wood through sealing. This is especially true in the drying of thin veneers and high-temperature drying of softwoods. You may obtain more detailed information on this subject from USDA Agriculture Handbooks Number 188, Dry Kiln Schedules for Commercial Woods.
The rule of thumb is 1 year per inch of thickness, but that depends on the species, your climate, and whether you plan to kiln dry it. You can kiln dry wood at any point, but the drier the wood, the less time it will spend in the kiln, and the less it will cost you. Because of hardwood’s denser and more complex structure, its permeability is much less than that of softwood, making it more difficult to dry. The presence of large knots can result in dramatic and exaggerated warp during drying. Please note that this answer is regarding Gorilla Wood Glue, which is a water-based PVA.