CountryByNet.com Forums :: What is "seasoned" firewood?

""Is there some factor (other than water) present in recently split wood that's not in wood seasoned longer??""

The only factor, other than water, is the species of wood. Softwoods such as pine, fir, hemlock, spruce, differ from hardwoods such as oak, hickory, elm, maple, birch, etc. in their density, cell size and distribution, and in their ability to dry out.

Some woods, such as hickory, burn well even when they are not dry. But regardless, if there is moisture in the wood (and there always will be some), that moisture has to be converted to gas (steam) with heat which robs energy from the wood when it burns. So the more moisture, the less heat is available to heat the air. Petty straight forward.

When wood is burning, and boiling off the water in the wood, it is not as hot and the gases are cooler, which will condense out in the smoke stack quicker and easier. This condensing is what forms the creosote. Some woods produce more creosote than others, because of the chemical makeup of the wood.

In many years that I have burned wood, I find that it does not have the heat value I want until after being split, and stacked under cover for a minimum of 2 1/2 to 3 years. It doesn't rot if under cover, it continues to lose moisture, and because it is red oak or white oak, it does not burn up quickly in the wood stove. Two to three pieces will burn for 8 - 10 hours, and at that time, have enough hot coals to ignite two more pieces, with out lighting a match. That does not happen with wood that is not dry.

Granted, dry or seasoned means something else to different minds, as the response indicate here. I don't mean to imply that they are wrong, as that is likely the way they want their wood to be when they burn it. And that is fine.

Moisture is found in wood in three forms. The moisture called "free water" is found above what is termed "fiber saturation point" which for most woods is about 30% moisture content (oven dry basis). The water above 30% is "free water" found in the cells (voids) of the wood. If one was strong enough, you could wring that water out like wringing out a wet sock. Under 30%, the water is bound up in the cell wall structure and when removed (with energy) it causes the cell walls to shrink. One will notice this shrinking by the cracks that form in the ends of the firewood. This moisture comes out of the cell walls quickest from the ends of the wood pieces. It takes a long time to get the center cells within the pieces to give up the water bound up in the cell walls.
The third form of water in wood is at moisture content under 5%, and is chemically bound up and cannot be removed. So the driest you can get wood is about 5%. The driest you can get wood by just air drying is about 12%. That will take about three years in the northern US, quicker in the South (like Oklahoma). Wood doesn't dry much in the cold air during winter. The relative humidity is too high. In fact, dry wood if left outside in the winter will probably pick up moisture. Good to move as much dry wood indoors (yes, often impractical) in the fall before cold sets in for the winter.

One can determine the moisture content of wood by weighing a small piece (nearest gram if possible) then drying it in an oven (250 F) until it stops losing weight, then dividing the difference between the two weights (green - dry) by the dry weight (times this by 100 to get moisture content). Also, the wood is air dry if and when it stops losing weight. Because the ends of the firewood pieces are dryer than the center of the stick, the center will be the best place to cut a test sample (if one is serious about knowing).

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