Before you load the chain saw into the truck to gather firewood or write that check for a cord, be sure you know what to look for in the wood supply. Firewood should be properly seasoned to maximize burn efficiency and long-lasting heat. Knowing what to look for in seasoned firewood will go a long way to keeping you warm and extending the life of your wood supply as well as your fireplace, stove and chimney.
Seasoned firewood contains about 20 percent to 25 percent moisture content, compared to freshly cut or "green" wood, which can contain about 45 percent water. Softwood reaches good seasoning in six to 12 months, while hardwood takes a bit longer. During this time, whether the wood rests on the forest floor or sits stacked and properly stored at your home, wind and sun work to evaporate excess moisture.
Wood contains microscopic tubes that carry water from the roots through the tree. When a tree falls, water transportation ceases, but moisture remains. This moisture must evaporate to give you the best wood to burn. If you try to burn green wood, the heat produced will first attempt to dry the wood and then put any remaining energy into actually burning it, resulting in minimal heat output and increased creosote buildup in the chimney and flue.
Identifying Seasoned Wood
Regardless of whether you want softwood (like fir or pine) or hardwood (like oak, ash or peach), look for a few common characteristics. Seasoned wood is brittle and nearly white on the inside. When compared to green wood, seasoned wood is lighter given that it contains less moisture. Seasoned wood contains more splits and cracks and makes a dull "thud" when knocked against another piece of wood. Identifying seasoned wood is an inexact science, and the best way to identify it is to keep track of its age and storage method yourself.
Due to the lack of moisture, seasoned wood ignites quickly, lasts long, burns efficiently and allows for minimal creosote buildup. "Creosote is the condensation of unburned, flammable particulates present in the exhausting flue gas [smoke]" and is highly combustible, according to Mastersweep.com.
Store seasoned firewood properly, without a tarp and away from extensive exposure to moisture. The tarp blocks sun and wind exposure, both of which promote natural evaporation of moisture from wood. Long-term exposure to rain or snow might prompt the wood to reabsorb water. Try to keep wood elevated, especially if you expect your supply to last longer than one cold season. A protective shed that allows for air circulation extends the health and "seasonality" of the wood if you expect your supply to last more than a year or two.
As the Chimney Safety Institute says, "The heat produced by burning firewood is actually the energy of the sun..." When we light it in our fireplace, we simply release the energy and bask in the sun's natural warmth.
- Image by Flickr.com, courtesy of Rene Ehrhardt