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Date: Tue, 14 Nov 2006 23:41:13 -0800
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Common Names - Moisture Meters - Confusion & Consternation. HELP!

Short Version:

I have 200 bf of "english sycamore" - much of it quarter sawn and
gorgeous.
I also have a Wagner MMC 205 moisture meter.

Problem:
Need to give the moisture meter the specific gravity of the "english
sycamore". BUT "english sycamore" is a common name, also known as
"european maple" and it isn't actually sycamore - it's a maple. I've
found THREE different specific gravity values for "english sycamore" -
0.61, 0.66 and 0.72. Short of sending a sample to a government agency
to find out what it is does anyone here have any suggestions?

LONG Version:

If you make solid wood furniture you need to accomodate wood movement.
The amount of movement(tangential, radial & axial) is a function of the
type of wood, its moisture content when worked and its expected changes
in moisture content when it gets to where it will live.

There are devices which will quickly measure, indirectly, the moisture
content of a piece of wood. They come in "pins" and "pinless" flavors.
BUT - to get the actual moisture content you need to know the Specific
Gravity of the wood being measured. Moisture meters usually come with
pages and pages of tables of various woods and their specific
gravities. Some allow you to set the specific gravity and have the
meter give you the moisture content directly. Others require that you
adjust the meter reading for the wood you're measuring to get its
moisture content.

It's getting the right specific gravity for your piece of wood that can
get tricky - if you only have the "common name" of the wood in
question. You see, "common names" vary from place to place, unlike the
scientific latin names. And it's not just a Po-Tay-Toe / Po-tah-toe
pronunciation thing. Common Names are often based on the appearance of
the tree, or its leaves, or its fruit/nuts and a similarity to another
familiar tree. Take maple for example. There are over a hundred types
of maples with maybe 50 called "japanese maples". Then there's Red
Maple, Sugar Maple, Soft Maple, Hard Maple, Rock Maple, English Maple
and Black Maple, to name just a few of the "common names" given to
maple. The commonality for maples seems to be the leaf shape with its
five veins. But when you try to find the specific gravity of "maple"
you find quite a range. Use the wrong specific gravity and your
moisture meter reading becomes almost useless.

I've got 200 bf of "English Sycamore" - which turns out isn't a sycamore
at all, but rather a maple - the "acer" family. And depending on who you
reference, "English Sycamore" is also called "European Maple" or
"Sycamore Plane", the former "acer campestre" with a SG of 0.66 and the
latter "acer pseudoaplatanus" with a SG of 0.61 a difference of 7-8 %
depending on what you use for the denominator. But if it's Acer
saccharum or Acer Negrum, aka Hard or Sugar Maple for the former, Black
Maple if the latter, the Specific Gravity is 0.72. That's 18% denser
than Acer pseudoplatanus.

Now one could take a piece of wood of a measured size, weigh it, stick
it in an oven and heat it, weigh it, heat it some more and keep this up
til the weight stabilizes. At that point, if you measure its length,
width and thickness again, you have its minimum dimensions and you have
its "oven dried" weight. With that data you can calculate its density.
With that density you can calculate its Oven Dried Specific Gravity (the
wood's density over water's density). But is that the density you need
for adjusting the meter the wood's "green" density or its "oven dried"
density - or something else?

I plan on making the face frames, doors and drawers for my kitchen
cabinets out of this "english sycamore", bought the "Shaker" cope and
stick router bits, the panel raising bit, have a decent moisture meter
(Wagner 205)
and still don't know how I'm going to get the moisture content of this
wood.

HELP!!!!!!! How do I tell if the "english sycamore" I have is Acer
pseudoplatanus, Acer campestre , Acer saccharum or Acer negrum?

Go to
http://www2.fpl.fs.fed.us:8080/tilia...1&type=browser,
plug in the common names of some of the species from your table, and see
whether the numbers in the table correspond to the green density or the KD
density. Your density for hard maple, the only species that you mention for
which I could find a specific gravity listed in the database, is higher than
the listed KD density, so it seems very likely that what you need is the KD
density and not green.

Note that many species show significant variation in dried specific gravity,
so the "book" value might not be all that accurate anyway.

If worse comes to worse if you're in the US the government will identify the
species for you for free. If you're not in the US they'll still do it for a
nominal charge if I recall correctly.