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Seasoning and Storing Firewood
Wood, which has recently been cut and is still full of sap and water is known
as "green" wood.
Green wood will generally burn poorly and inefficiently, because it can have
over 50% water in its cells. It may be hard to light, smoulder, not put out any
heat and cause more than the usual amount of creosote to build up in your
chimney.
So your aim should be to dry the wood out to below 20% moisture content,
this process is called seasoning. As the name implies, you should store your
wood for a season or so, while it dries, but there are things you can do to
speed up seasoning by cutting the wood now rather than just before you use
it.
Wood is composed of bundles of microscopic tubes that were used to
transport water from the roots of the tree to the leaves. These tubes will
stay full of water for years even after a tree is dead. This is why it is so
important to have your firewood cut to length for 6 months or more before
you burn it, it gives this water a chance to evaporate since the tube ends are
finally open and the water only has to migrate a small distance to escape.
Splitting the wood helps too by exposing more surface area to the sun and
wind, but cutting the wood to shorter lengths is of primary importance.
Here’s how you can tell whether your wood is ready or not: Well seasoned
firewood generally has darkened ends with cracks or splits visible, it is
relatively lightweight, and makes a clear "clunk" when two pieces are struck
together. Green wood on the other hand is very heavy, the ends look fresher,
and it tends to make a dull "thud" when struck.
Another thing you can do to help is store your wood properly. Store it off the
ground by building the pile on some longer logs (or whatever method you
can devise). A shed or shelter with an open side makes an ideal storage place,
as the air can circulate around the logs and help to dry them out.
Unventilated spaces or plastic tarps, which never get taken off will prevent
the drying and evaporation process and cause moulds and rot. So, if a tarp is
your only option, take it off frequently to air the wood on fine days. And
remember to put it back on again. Seasoned firewood will reabsorb large
amounts of water if exposed to rain, snow and excessive dew, which is liable
to make it rot and be unfit for making a good fire.