Three of the five major spruces in North America grow in the eastern half of the United States and Canada. Collectively called eastern spruce, they are red spruce (Picea rubens), white spruce (P. glauca) and black spruce (P. mariana). Red spruce is found primarily in New England, the Appalachians and eastern Canada, while white and black spruce are found in the Great Lakes region, New England and eastern Canada. Their wood is impossible to separate visually once sawn into lumber. The properties are also essentially identical.
Eastern spruce trees are usually not very large (seldom over 2 feet in diameter) and the lumber they produce often has very small knots. Although spruce is known for its high strength compared to its weight, the abundance of other softwood species with clearer wood in much of its growing area resulted in limited harvesting and manufacturing of eastern spruce lumber in the past. Among its uses, in colonial times, the wood was utilized for mast and spars; this use continues today for small sailing boats.
Eastern spruce also still is used for piano sounding boards, violins and other musical instruments due to its excellent resonance properties. It also has potential applications in furniture and cabinets due to its gluing, machining, stability and strength properties. Perhaps the only limiting factor is, because of its past history of usage and its processing into construction lumber.
Today, pulpwood is probably eastern spruce’s number one use, followed by construction lumber, especially 2 x 4s and 2 x 6s, much of which is imported from Canada and sold under the species grouping of SPF lumber (spruce, pine, fir).
Processing suggestions and characteristics
Density. The three spruces have a density of approximately 27 pounds per cubic foot at 7 percent MC. This is one of the lightest-weight species in North America.
Drying. The spruces dry easily with few defects. If logs or green lumber are stored in warm weather, blue stain in the sapwood is common. Shrinkage in drying is 6 percent. Final moisture content should be between 7.5 to 9 percent. As with most softwoods, higher MCs are desired, because excessively dry wood will develop torn grain and may require increased glue spread to avoid a starved joint.
Gluing and machining. They machine very easily, with few defects except around the knots. Gluing is excellent. The softness means the wood is quite forgiving if gluing conditions are not perfect.
Stability. The spruces are subject to minimal size changes when the MC changes — about 1 percent size change running across the grain parallel to the rings (tangentially) for each 5 percent MC change, and about 1 percent size change across the rings (radially) for each 10 percent MC change.
Strength. Spruces are medium in strength and stiffness. Bending strength (MOR) averages 10,800 psi for red and black and a little lower for white. Hardness averages 500 pounds. Stiffness (MOE) averages 1.6 million psi in red and black, with white 1.43 million psi.
Color and grain. The grain is straight, fine and uniform. The wood is pale white, with the sapwood and heartwood indistinguishable most of the time. There is no appreciable odor when dry.
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