A lot of time, money and effort goes
into drying (or "seasoning") timber. Why?
Timber from a freshly sawn log is called
"green" timber and has a very high moisture content
(MC) of around 100%MC.
sawmilling, the boards are stacked for air drying, using small
spacers (called stickers) to separate the boards. Over time,
the moisture evaporates off and the boards dry out. It takes
a year for a 1" board to dry properly, two years for a
2" board and so on. When the board has dried fully to the
centre, it will have a moisture content of about 18 to 20%MC.
During the drying process, some boards
will warp, twist, cup, bow or split. Thankfully, most boards
will stay straight and sound, but every board shrinks
by as much as 10%.
If a board is going to "misbehave"
it is obviously far better for it to happen during the drying
process than after it has been used in a fine piece of furniture!
This is why timber needs to be properly dry before use.
Once air dried, wood can be used for
certain applications, for example outdoor uses. The moisture
content of the wood will vary according to the environment in
which it is placed. Increases in moisture content will cause
the wood to expand. A decrease will cause the wood to shrink.
The stability of timber is important,
and especially so with indoor furniture. Kiln drying timber
down to 10%MC gives wood greater stability and reduces the extent
to which expansion and contraction occur.
The Equilibrium Moisture Content (EMC)
of wood is the moisture content that a piece of wood reaches
when it is consistent with it's environment. For example, wood
in a garden bench outside will have an EMC of about 20%, as
with air dried timber. Wood in a piece of furniture in a modern
house will have an EMC of nearer 10%.
wood is to be used indoors, it is therefore going to be far
more stable if it is dried down to 10%MC, and this is done using
Kiln drying wood is a lengthy process,
and carries several risks with it. All of the wood in a kiln
can be destroyed if the kiln is not operated correctly.
We use a 16ft long dehumidifier kiln,
which we built last year, and so far we have had no problems.
It takes about 3 weeks to bring air dried oak form 20%MC down
to 10%MC, and more than double this for 2" oak.
Once dried down to 10%MC, the wood is
ready for use indoors. There will still be some movement in
the timber if it's environment is allowed to alter and so furniture
is carefully designed to accommodate this movement with minimal
For more information on What We Do, visit:
story of resurrection...
In 2004, this 24" Sagar planer
thicknesser was sitting in a shed near Punchestown, Co Kildare
where it had been for many years.
It was rescued from the old Power's
distillery in Dublin which closed in 1976, almost 30 years ago.
machine was originally made by J. Sagar & Co of Halifax,
England. The age of the machine is not known, but Sagar closed
down in 1958, so we estimate the machine to be 50 years old.
joint owners of the planer thicknesser very kindly allowed us
to take it and give it a new life here at Lisnavagh, and we
are extremely grateful to them for allowing us to do this.
last December, Gerry
van Soest has painstakingly stripped the machine down to the
last nut & bolt and rebuilt it. Despite a good coating of
rust, the machine was in extremely good condition. Very few
parts needed replacing and we were fortunate enough to have
someone nearby who could machine these for us.
Sagar planer thicknesser has now been completely restored and
will be fully operational later again this month. It will give
us the ability to plane or thickness boards up to 600mm wide
- and give this wonderful and beautifully crafted machine the
new lease of life that it so richly deserves.