What is Seasoned firewood?
A wood fire is a pleasant, inexpensive and environmentally friendly way to heat a home. However, the most important factor in determining firewood quality is the moisture content, or the amount of water that is in the wood. Wet wood of any species makes poor firewood. The “green” wood in living trees contains large amounts of water. The moisture content of wood (the amount of water) is expressed as a percentage of the dry wood weight. The green moisture content of wood is normally above 60 percent, and can range as high as 120 percent for some species. Moisture content of greater than 100 percent means that there is more water in the wood than there is dry wood substance. Some species of wood are relatively dry when green and some species dry faster than others. Furthermore, species like oak and hickory are high in density, which means that there is more fuel per piece of firewood than in lower-density species – this would be considered seasoned hardwood logs. However, all wood species can be acceptable wood fuel if they are dry. Even low-density species such as poplar and softwoods such as pine will burn well when properly dried.
Dry Firewood = Seasoned Firewood
Seasoned Firewood – ‘Seasoning’ refers to the drying of firewood over time. Seasoned Firewood should be as dry as possible. Firewood that is prepared in the spring should be dry enough to burn the following fall.
However, the passage of time alone is not enough to ensure proper seasoning; firewood needs to be cut-to-length, split, stacked and exposed to drying breezes. Logs, un-split firewood, pieces that are touching the ground or pieces that are deep inside a firewood pile will dry very little, even after many months. Properly seasoned firewood (moisture content below 20 percent) is critical to getting the most from firewood. Dry firewood delivers more heat, because less heat is used up evaporating water. Dry wood also burns more completely, ensuring a cleaner and safer fire. Incomplete combustion of wet wood produces dirty smoke that can accumulate as creosote in the chimney. If this creosote builds up, it can eventually ignite and cause a chimney fire. Seasoned firewood should always be used for fire places, wood stoves, wood burning pizza oven, and any wood burning endeavor!
Why it’s not good to burn wood with moisture (non seasoned firewood)
If you try to burn green wood, or non seasoned firewood, the heat produced by combustion must dry the wood before it will burn, using up a large percentage of the available energy in the process. This results in less heat delivered to your home, and literally gallons of acidic water in the form of creosote deposited in your chimney.
How to determine the moisture content in wood
The moisture content of wood is a basic property that can impact subsequent machining, gluing, finishing, and product performance. It is the job of wood product producers to establish a moisture content in the wood that will be similar to what the wood will experience in service. To accomplish that, manufacturers must develop a standard procedure that will measure wood moisture content consistently and accurately.
Ovendry Moisture Measurement – Here is where we get a little scientific (Nerdy)
The “true” moisture content (MC) of wood is defined by the ovendry method. According to the Wood Handbook, ovendry wood is defined as “wood dried to a relatively constant weight in a ventilated oven at 102 to 105 oC (218 oF +3 oF).” An oven with circulating fans is preferred over a convection oven, but it is more important to have a working thermometer inserted in the hole in the top of the oven.
In the kiln drying of lumber, moisture sections cut from sample boards are recommended to be 1″ along the grain. For weighing these moisture sections, the balance should have a capacity of at least 1,000 grams and weigh to at least 0.1 gram (0.01 gram is preferable). For most sample boards, the balance should have a maximum capacity of 15,000 grams (33 pounds) and weigh to the nearest 1 gram. For operations that process wide, high density hardwoods the maximum capacity should be 20,000 to 30,000 grams (44 to 66 pounds).
Firewood moisture meters allow the user to rapidly and accurately estimate wood moisture contents less than 30%. Most hand held moisture meters are typically either resistance (pin type) or dielectric (flat plate) meters. In the past, meter readings needed to be corrected for species and temperature by hand using printed tables. Today, commercially available state-of-the-art moisture meters have species and temperature corrections built into the digital circuitry. In addition, the newer meters are capable of taking multiple measurements and storing them internally, providing the ability to calculate and display mean and standard deviation statistics, and the option of downloading the MC data to a computer. The ability to transfer data to a computer is a significant plus if you want to plug moisture measurement into a quality control program.
Seasoned firewood is required for the best wood burning experience.