Birch has been providing important forest products for North American inhabitants for many centuries. Certainly the bark of paper birch used for canoes is one use that comes to mind. Seeds are consumed by songbirds including the common redpoll, pine siskin and chickadees. Ruffed grouse feed on seeds, catkins, and buds. The yellow-bellied sapsucker uses yellow birch as a summer food source. Paper birch wood is also easily worked with hand tools, and was used for bowls and other woodenware. Today, paper birch is used for tongue depressors, ice cream sticks and toothpicks. Sweet and yellow birch are heavy, hard and strong and are used for cabinets, paneling and veneer.
Today, there are three commercially important birch species: yellow birch (Betula alleghaniensis, which means "from the Alleghanies"), paper birch (B. Papyrifera) and sweet birch (B. Lenta). Properties (especially strength) vary considerably among these species.
The tree, and therefore lumber at sawmills, is found from eastern Minnesota south to northeastern Iowa, northern Illinois, northern Indiana; eastward into Ohio, Pennsylvania, and New Jersey; and south through the Appalachians to northern Alabama and Georgia; and northward into Quebec, Ontario, New Brunswick, Maine, upper Michigan, and New York, with about 50 percent of the growing volume in Quebec.
Even though the birches have very favorable properties, these species are often ignored and overlooked.
Processing suggestions and characteristics
Density. Yellow and sweet birch average about 43 pounds per cubic foot at 7 percent MC. This is roughly the same as oak. Paper birch averages 38 pounds per cubic foot 15 percent lighter than the other two birches.
Drying. All the birches dry very easily. Slow drying can result in some brown stain and sticker stain development, especially with paper birch. Likewise, initial temperatures over 120 F will cause some darkening. There is only a little risk of surface checking. Warping in lower grades is a risk. Shrinkage in drying is 5 percent.
Final moisture contents for birch should be between 6 to 7 percent. Slight MC variations outside of this range are not suggested due to birch's high shrinkage.
Gluing and machining. Yellow birch and sweet birch are moderately difficult to glue and require flat, true surfaces that have been recently prepared. Pressures must not be too low. Paper birch glues more easily.
Yellow and sweet birch machine quite well with sharp tools. Paper birch machines even easier, and has been used for turned products as well. The wood veneers well, providing smooth surfaces.
Stability. Birch is subject to modest size changes when the MC changes about 1 percent size change for each 3 percent MC change running across the grain parallel to the rings (tangentially), and about 1 percent size change for each 4 percent MC change across the rings (radially).
Strength. The birches are quite strong. For yellow birch, bending strength (MOR) averages 16,600 psi. Hardness averages 1,260 pounds. Stiffness (MOE) averages 2.0 million psi. Sweet birch is 16,900 psi, 1,470 pounds and 2.2 million psi. Yellow birch and sweet birch are stronger and stiffer than hard maple. Paper birch is 12,300 psi, 910 pounds and 1.6 million psi, considerably lower than the other two, but higher than soft maple.
Birches, especially yellow and sweet, are known for their tendency to split when nailed. Using blunt pointed nails or predrilling the holes for screws will offset any risk.
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