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THE MUSIC TRADE REVIEW
VARYING WEIGHT IN WOODS
Presence of Moisture Is Largely Responsible
for the Difference in Weight Between Given
Specimens of Wood—Interesting Statistics
In a recent bulletin prepared by J. A. Newlin,
of the Forest Products Laboratory, Madison,
Wis., figures are presented showing how much
woods vary in weight and giving some reasons.
These facts should be of particular interest to
those who handle seasoned material.
Any piece of wood selected promiscuously
may contain anywhere from four per cent, mois-
ture, as in some kiln-dried material, to two times
as much moisture by weight as wood material,
as in occasional pieces of white fir. In view of
this fact it is necessary to divide wood into
three groups as to moisture in order to effect a
definite comparison. These groups represent
a maximum amount of moisture, as in green
wood, wood with no moisture, or oven dry wood,
and wood with an intermediate percentage of
moisture present, or air dry wood.
The weight of green wood depends upon the
weight of the wood substance itself, the moisture
content, and the weight of other contained sub-
stances, such as resin. The various species
contain widely different amounts of moisture in
tlie living tree; for example, white ash and black
locust are always comparatively dry; black ash
and the oaks have about twice as much moisture,
and chestnut and buckeye have three times as
much as the white ash; the white and red,cedars
are comparatively dry, while cypress and white
fir contain large amounts of moisture.
Position in the tree also affects moisture con-
tent. Most hardwoods show a fairly uniform
distribution of moisture throughout the tree and
the variation in the hardwood species is com-
paratively small. The conifers, on the other
hand, show a wide variation in moisture content.
In the same tree, as a rule, a large difference in
the percentage of moisture exists between the
heart and sapwood and, in some instances, be-
tween the upper and lower parts of the tree.
Long-leaf pine and most other conifers have
very low moisture contents in the heartwood
and very high in the sapwood, causing young
thrifty trees to run heavier than old over-mature
trees of the same species. Tamarack and cypress
are exceptions, having fairly uniform moisture
contents throughout the tree. Sugar pine and
Western larch, due to resinous material as well
as water, are very heavy at the butt.
Variation of 5 per cent, above or below the
average weight per cubic foot for a given species
is to be expected in the case of species having
a fairly uniform moisture content. This varia-
tion may, however, run as high as 20 per cent,
occasionally. With species that do not have a
uniform moisture content about 10 per cent,
variation in the weight per cubic foot may be
expected with occasional trees varying as much
as 40 per cent. These figures apply when con-
sidering small amounts of the wood, such as
timber from a single tree. In large shipments,
as would be expected, the average weight is
much more likely to be nearer the average value
for the species, although in the conifers, as was
previously pointed out, the character of the stand
would very materially influence the weight per
cubic foot.
Air-dry weight varies . largely on account of
the wide variation of moisture content implied
by the term. Some species lose the moisture in
Illllllil
The Ohio Veneer Co,
CINCINNATI, O.
HI Importers and Manufacturers of Figured §§§
II Mahogany and Foreign Woods for high-
§= grade piano cases and cabinets.
one-tenth the time of others. Some material is
air-dried to reduce its shipping weight and is
considered dry when it ceases to lose moisture
fairly rapidly, while for sonic of the more exact-
ing uses the material will be carefully dried for
months or even years until it reaches as low a
moisture content as possible under the condi-
tions and moisture within the stick has become
uniformly distributed. For example, in air-dry
telephone poles of cypress the moisture content
may be over 40 per cent, of the oven-dry weight
of the wood, while for high-class finish lumber
of the same material it will probably be below
10 per cent. Thus it is seen that different con-
ditions of air-drying may affect the weight of a
species so that one class of material will be
only about three-fourths as heavy as material
of another class. However, for any given class
of timber the figure is fairly uniform and the
weight per cubic foot will have about the same
percentage variations as in the green hardwoods.
The weight per cubic foot of absolutely dry,
or oven-dry material, varies somewhat less in
percentage than the weight of either green or
air-dry timber. The timber from any given tree
will one-half the time fall within 4 per cent, of
the average value with occasional values as
much as 16 per cent, above or below the aver-
age. These variations are about the average for
most species. The long-leaf pine and Douglas
fir, however, show variations about one and one-
half per cent.
ELIMINATING PINHOLES
Some Practical Suggestions of Benefit to Piano
Manufacturers
The question, What is the cause of pinholes
and what can be done to avoid them? is an-
swered in many ways by different manufac-
turers, says G. Peterson, in Veneers. Some say,
shellac the mahogany before it. is filled; others,
before and after it is filled, and others that
it is in the veneer, and that certain kinds of
veneer will always show pinholes, but I have
not found it so. In the large piano factory
where I am employed we use from the cheapest
to the best grade of mahogany, and I think if
you who are having this trouble will spare the
time to try my system, you will find it will do
away with most of your pinholes.
First, bear in mind that the work in the fill-
ing room and the material used are the building
of the foundation of your finish, and should have
all your spare time and attention, for if it is
started right it will be right in the end, but
if started wrong it can never be made right on
top, and time and money spent in the filling
room is doubly saved in other departments.
I have used many different fillers, and I am
sorry to say that there are few that I call first-
class ones. Take mahogany, for instance, as
that seems to be the cause of most of the trou-
ble.
When using water stain, let stand for
twenty-four hours before sanding, as it is neces-
sary for all woods to be in perfect condition
and thoroughly dry at the bottom of the pore
before filling. Where oil stain is used, it should
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m
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MATAWAN, N. J.
47
ADVICE?
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stand at least forty-eight hours; then fill, but
be sure and have a good grade of filler, one that
will not dry too fast, or it will get brittle and
dust, nor too slow, as it is liable to remain
fatty at the bottom of the pore and give you
trouble afterwards. Do not use your filler too
heavy. Some seem to think that it should be
heavy enough so that the grain is all filled up,
and the thicker the filler the better, but I find
that it is only a waste of material, for what be-
comes of the material that lays on top if the
pores are already filled? Put your filler on
thin and rub the pores full. I find the best re-
sults are gotten when a filler is mixed about 50-
lbs. of paste filler to 1-gal. of boiled linseed oil
(best grade) and 4-gal. benzine, which makes
10-gal. and should be dry and ready to rub off
in not less than fifteen minutes. If it should
take a little longer, add a little japan, as filler
that turns flat in fifteen minutes will give you
very little trouble. Never coat under forty-
eight hours, no matter what your filler manu-
facturer tells you, and let stand as much longer
as you possibly can, as time is like fresh air—
it does no harm.
Do not keep your filling room closed and
stuffy. Before putting your work in varnish
room, take a piece with a large surface, place
a magnifying glass over the large pores, pick
the filler out with a pin, and if it is not dry
in forty-eight hours you have a poor filler. Use
a wash coat of shellac. Shellac, if used prop-
erly, does no harm, but do not try to make a
coat out of it, for it injures your color and will
not stand the weather conditions. Cut your
shellac about 1^-lbs. of gum to 1-gal. of alco-
hol, and I am sure most of your pinhole trouble
will disappear.
INVISIBLE
HINGES