Be careful with firewood choices

For those planning to supplement winter's furnace heat with a wood-burning stove or fireplace, forester Charles Barden has two words of advice: "Be careful."

Gathering or buying good firewood requires some savvy, explained Barden, who's a forestry specialist with Kansas State University Research and Extension.

"You rarely can get into cutting your own firewood quickly. You don't want to burn wood that has aged for less than six months since being cut," he said. "A year of aging is even better.

"Relatively speaking, fresh or green wood is 'juicy.' It's more likely to pop out burning sparks -- a definite hazard. When you add green wood to a fire, the heat has to dry it out before the wood will burn, and that leads to a smoky fire and creosote buildup. Plus, green wood doesn't produce as much heat."

The dividing point between selling wood as "green" or "seasoned" is a gray area, Barden said. Firewood vendors typically decide it's somewhere between six and nine months of aging.

"Surface cracks on the ends of the logs aren't a good indicator. Those cracks can show up just a few weeks after the logs have been cut," the forester warned. "If you whack pieces of firewood together, though, the dry logs will have a ringing sound. Moisture-laden green wood makes a dull thud."

Finding out about wood species is an important step for buyers planning to help heat their home with wood, rather than just build an occasional fire for a cozy Saturday evening, he said.

Many evergreens -- including low-cost and widely available pine -- contain a sticky sap called pitch. This sap is why the evergreens' wood is likely to spark, crackle and pop dangerously. Pitch also vaporizes in fire's heat and rises with the smoke. As it cools, however, the vapor condenses on chimney walls -- or on older pitch deposits -- and becomes an increasing fire hazard.

"Pine can be great, easy-to-start kindling," he added. "But you're asking for trouble if you feed your wood stove a steady pine diet."

"Mixed hardwoods" can mean almost anything except pine and cedar. Oak is known as the premium fuel wood. But, other species can have higher or equal heat values.

Listing from best to worst on the heat output scale, Barden's recommendations for the hardwoods typically available in the central High Plains are: Osage orange, black locust, hickory, pecan, oak, honeylocust, mulberry, sugar maple, green ash, black walnut, hackberry, sycamore, silver maple, cottonwood and willow.

"What you want for a heat source are seasoned hardwoods such as these," he said. "You should store them neatly stacked outdoors on supports that are at least 4 inches off the ground to discourage rodents and insects. Stack the logs bark side up, too, and preferably cover them with a tarp. The drier the wood stays, the longer seasoned logs will remain viable firewood."