Gardening Tips: November 25, 2015
The smell of wood smoke is beginning to permeate the morning air as Indian Summer gives way to Old Man winter. This is the time of year when many people start to think about cutting or buying firewood for the upcoming winter. We should have been thinking about this six months or more ago because freshly cut, i.e. “green” wood requires at least six months to “season” or dry out. Most tree species contain as much water by weight as they do wood when the tree is still standing. A 16-pound chunk of green oak, hickory or maple must be heated long enough and at a high enough temperature to evaporate at least eight pounds of water before the wood even begins to burn. That is a lot of energy to waste as you wait for the wood to begin to burn.
Picture a gallon jug of water for every large, unseasoned log that you are tossing into the woodstove. Even fully-seasoned firewood will still contain as much as 20 percent moisture by weight because that is about as “air dry” as wood can get. Lumber that is used in construction is usually kiln dried down to about four or five percent moisture content which explains why old two by fours and pieces of furniture burn so well.
If you are buying firewood, look for cracks or “checks” on the ends of the individual pieces of wood, which usually indicates that the wood has been allowed to dry somewhat. If you really want to check the moisture content more precisely, you can cut a piece of firewood into a size that is small enough to fit in your oven. Weigh the piece of wood first and put it in a 250-degree oven. Remove the wood after a half hour or so and weigh it again to see how much weight it has lost. Continue this process until the wood is no longer losing weight . Then, calculate the original moisture content by subtracting the dry weight from the original wet weight.
Hardwoods vs. Softwoods
Trees are classified as either “hardwoods” or “softwoods” based solely on whether or not the tree is a conifer or a deciduous species. Many types of softwood, such as pine or spruce, do have less dense wood than species like oak or hickory, but some tree species that are technically hardwoods, such as willow or aspen, actually have less dense wood than hemlock or pine. All wood that is properly dried will burn, even pine, hemlock or spruce, but it pays to buy the heaviest, most dense wood available. That is because firewood is sold by volume, not weight, with a full cord being defined as a stack of wood that is four feet wide, four feet tall, and eight feet long. A face cord is four foot tall by eight foot long by only as wide as the average length of each piece. If the individual pieces of wood are 12-inches long, that particular face cord would contain one quarter of a full cord. If the individual pieces are 18 inches long, that face cord would contain one third of a full cord and so on. Beware of buying “truckloads” of unstacked wood because it is impossible to actually determine how much wood is on the truck until it has been restacked.
Very few pickup trucks can carry a full cord of firewood regardless of how it is stacked. With fuel oil prices lower than they have been for years, the price of firewood has also gone down, but you can still expect to pay more than $200 for a full cord of seasoned hardwood. There are approximately the same number of BTUs in a full cord or firewood as there are in 100 gallons of fuel oil, but very few wood burning stoves can burn the fuel as efficiently as a well tuned oil burner.
Cutting, splitting and stacking your own firewood is a very gratifying pastime and can be excellent exercise but it is also rather dangerous. Lumberjacks pay the highest rate of workman’s compensation insurance in all of the country and for good reason. Chainsaws can be deadly and there is no such thing as a “minor” chainsaw accident. No one should even start a chainsaw unless they are wearing proper safety equipment. That includes ear and eye protection, a hard hat if trees are being felled and protective chaps. After watching my son in law “pruning” some trees on his property without any safety equipment at all, I now know what he is getting for Christmas.