What do firewood and a fine wine have in common? Both often improve with age. This is why firewood left from last year tends to burn more efficiently than wood bought during the current burning season. It's all a matter of curing, or seasoning.

As with a fine wine, firewood improves with curing. Firewood that has been dried to less than 25 percent moisture content is a more efficient heat source.

If you're buying firewood now, ask the seller how long it has been seasoned. Properly seasoned wood has a gray, weathered appearance and large cracks in the ends of the logs. The larger these cracks, the drier the wood. It's better to buy logs that have been split because they have more exposed surface area from which to lose moisture.

Burning unseasoned wood lowers the heat it produces and can cause a fire hazard. If you try to burn wet wood, the heat is used to turn the water into steam that goes up the chimney instead of providing warmth for you and your family. In addition, firewood that isn't properly seasoned causes a smoldering fire that generates creosote buildup in the fireplace and chimney. Over time, this buildup might lead to a chimney fire.

To speed the drying of firewood, remove the bark initially and stack the wood so that air circulates around it from all sides. During rainy periods, put a cover over the top of firewood. Do not cover sides of the woodpile because this prevents water evaporation from the ends of the wood.

Since firewood can reabsorb water, you need to care for seasoned wood properly. Stack seasoned firewood so air can circulate around it. Cover the logs to keep them dry during rainy weather.

Potential heat content of wood is another important factor, whether you are buying or cutting your own firewood.

Heat content is the amount of heat produced by an equal amount of wood. It is measured by how dense the wood is. Species like oak, hickory and beech are more dense than a species such as yellow-poplar. These more dense species, when seasoned properly, will provide more heat than the same volume of lower density species.

But do keep less dense species, such as yellow-poplar on hand if you have trouble starting a fire, because their lower densities make them a good choice for getting the fire started.

If you've just bought firewood, these tips will help you season it properly. Let the wood sit outdoors so that air circulates all around, but be sure it is protected from rainfall. Old pallets make a good platform to keep wood off wet soil. A tarpaulin is a good weather shield. Don't stack firewood against the home or a wooden fence because moisture condensation can cause mold and decay on wall sections and wood surfaces.

Ideally, the firewood should season for a year. It can lose considerable moisture from air drying for three months; six is even better.