Hard maple is a wonderful, expensive, nearly white wood used for almost every application imaginable both today and even prior to the colonization of the U.S. Uses include cabinets, furniture, bowls, bowling alleys, bowling pins, flooring, piano frames, dulcimers, spinning wheels, cutting boards, tool handles, veneer, pallets, particleboard, paper, firewood, and even railroad ties. What is this ubiquitous wood that we call maple?
Hard maple lumber, which is also called sugar maple, sweet maple, black maple and rock maple, comes from two species. Most lumber comes from sugar maple (Acer saccharum) and a small amount from black maple (Acer nigrum). Once hard maple lumber is manufactured, it is impossible, even under magnification, to separate the lumber into the two individual species. The name “hard” actually means that the lumber is substantially harder than the other maples, including the grouping called soft maple.
What person hasn’t had pancakes topped with wonderful, sweet maple syrup? Sugar maple is the tree that produces maple syrup. A grove of producing sugar maple trees is called the sugar bush. Also, did you know that it takes about 40 gallons of sap to make a gallon of syrup?
Processing suggestions and characteristics
Density
After drying to 7 percent MC and planing to 13/16 inch, maple weighs 3-1/3 pounds per board foot.
Drying
Maple is subject to blue staining and also chemical staining if not dried promptly and aggressively. Chemical staining occurs when the starches and sugars oxidize to pink or gray colors. For whitest color, maple must be stacked promptly after sawing using dry stickers. Maple is not exceptionally stable. Moisture content when the lumber leaves the kiln must be very close to the in-use moisture content. For most uses, 6.5 percent MC is the ideal final target, with almost all pieces being within + or – 1 percent MC.
Gluing and Machining
Maple requires surfaces to be glued to be freshly prepared and perfectly flat. Small errors will result in low strength joints. Because the grain in maple swirls quite a bit, planing and other machining operations will frequently be planing against the grain. To avoid chip out and torn grain, knives must be very sharp. Avoid over-drying the lumber (under 5.5 percent MC is over-dried), as brittleness and poor machining will be increased.
Stability
Hard maple changes width and thickness when the RH changes…about 1 percent size change running parallel with the rings (tangentially) when there is a 3 percent MC change, and 1 percent change across the rings (radially) when there is a 6 percent MC change.
Strength
Sugar maple is a little (10 percent) stronger, stiffer and harder than black maple. The bending strength is 15,800 psi, stiffness 1.83 million psi and hardness is 1450 pounds.
Color and Grain
Maple is a wonderful, nearly white wood. Unfortunately, there is no definition of “how white is white” so different suppliers will have different whiteness. In addition to the standard grades, some markets will also ask for “No.1 white”, which means that both edges and faces must be all sapwood (no brown heart). “No.2 white” means that one face and both edges will be sapwood. Hard maples frequently develop small little burls or curls in the wood, which we call bird’s eye. Bird’s eye maple is attractive and valuable.
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