WOOD EXPLORER
by Gene Wengert
gwengert@wattnet.net
Soft maple
In North America, the maple species are
in two groups: soft maple (red maple,
Acer rubrum, silver maple, A. sacchari-num, and bigleaf maple, A. macrophyl-lum) and hard maple (sugar maple, A.
Saccharum, and black maple, A. Nigrum).
Hard maples have ray cells of two different widths (as seen from end grain)
while soft maples have one width. Soft
maple also tends to be softer, lighter
weight, weaker and more dingy colored
than hard maple.
Of the two main soft maples, red maple
is about 10 percent harder and 15 percent
heavier than silver maple. Red maple
grows throughout the East Coast, from
Florida to Newfoundland and west to Texas and Minnesota. It prefers wetter sites,
but grows in a wide variety of climatic
and soil conditions. Trees are typically 70
It tends to be weaker,
feet high and
24 inches in diameter at maturity, but
larger trees do exist.
Silver maple also grows along the
East Coast, but is not found commercially in Florida, Louisiana or Texas. Silver
maple trees are a bit taller and a bit
larger in diameter than red maple.
Although not as strong as hard
maple, the name “soft” gives the wrong
impression. Soft maple is more than
adequate for many uses, including
furniture, flooring, cabinets, kitchenware,
clothes hangers and the like. ❮
lighter and softer
than hard maple.
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Density. Red maple weighs about 36
pounds per cubic foot at 7 percent
MC. This means that a piece of
lumber planed to 3/4 inch will weigh
2-1/4 pounds. Silver maple weighs
about 31 pounds per cubic foot at 7
percent MC. Dry, planed lumber will
weigh just under 2 pounds per BF.
Gluing and machining. Red and silver
maple are excellent gluing woods even
if conditions or gluing variables are
not perfect. These maples are very
easy to machine. Due to the softness
of the wood, very sharp tools work
best. Avoid moisture contents over 8.0
percent MC for best machining.
Processing characteristics and suggestions
Drying. Drying is easy. There is
little risk of checking and warp with
proper stacking and proper drying
conditions.
Slow drying can develop stain, both
fungal and chemical, so aggressive
drying ASAP after sawing is suggested,
especially for clearer more valuable
lumber. Dry stickers are essential as
well. In air drying, protecting the lumber from rain wetting is important.
Shrinkage in drying averages
about 6 percent in width for flatsawn
lumber and 3 percent in thickness.
Stability. The soft maples are less
responsive to humidity changes than
the hard maples. For flatsawn lumber, a 4 percent MC change results
in 1 percent shrinkage or swelling.
In the radial direction or thickness
of flatsawn lumber, an 8 percent
MC change results in 1 percent size
change.
Strength. Red maple has an ultimate
strength in bending (MOR) of 7700
psi, a stiffness (MOE) of 1. 39 million psi and surface hardness of 700
pounds. Silver maple has an MOR of
5800 psi, MOE of 0.94 million psi and
hardness of 590 pounds. Hard maple
comparable values are 9400 psi, 1. 55
million psi and 970 pounds.
Color and grain. The grain of these
two maples is very fine textured with
white sapwood (if dried rapidly). Heartwood is buff colored to darker brown
with sometimes a greenish coloration.
One unique characteristics of soft
maples is the development of small
boat shaped (or oval shaped) discolorations (several inches long and 1/4
to 1-1/5 inch wide). Oftentimes there
will be two or three 1/8-inch diameter
holes in the discoloration, adjacent to
each other. These characteristics are a
result of the Columbian timber beetle
activity in the living tree. This striking
defect adds a great deal of character to
an otherwise plain wood appearance.
