True fir trees, called true fir trees to distinguish the wood from Douglas fir, consist of more than 40 species in North America, but only seven species produce commercial timber. In eastern North America there is one main species, balsam fir (Abies balsamea) ranging from Alberta to Newfoundland, south to Wisconsin and New York. The majority of the wood is found in Canada; The balsam fir is the official tree of New Brunswick.
In the western part of the continent, commercial fir timber species are subalpine fir (A. Lasiocarp), California red fir (A.Magnifica), big tree (A. Grandis), noble fir (A.Procera), Pacific silver fir (A.Amabilis) and white fir (A.Concolor). Although trees can easily be separated into distinct species, when cut into wood, the wood of all fir trees looks the same.
Balsam fir is the most symmetrical of the Northeastern coniferous species, with a narrow pyramidal crown that ends in a slender arrowhead. The typical balsam fir is about 60 feet tall and 1-1/2 feet in diameter, although much larger trees (90 feet tall and 2-1/2 feet in diameter) are seen.
Balsam fir trees are popular for Christmas trees because the needles stay fresh for a long time.
The wood is used for furniture, lumber (2x4s, 2x6s), particleboard and paper pulp. As a lumber, the grade stamp will indicate the species as SPF (spruce, pine, and fir); fir is balsam fir, also called Canadian fir or eastern fir.
There are a few reports of contact dermatitis from the resin of real trees.
Treatment Suggestions and Features
Density. True firs are one of the lightest softwoods in North America, averaging about 25 pounds per cubic foot at 10% MC. This equates to 1.4 pounds per board foot for 8% ¾ inch MC planed lumber.
Drying. Fir trees have a high risk of developing fungal blue stain (also called sap stain) and being infested with ambrosia beetles which leave small holes in the sapwood when the MC is high. Prompt handling of the log to the kiln, or to other dyeing systems, is necessary to avoid and control these hazards. This wood dries very easily. Drying defects are few. The shrinkage on drying is less than 5%. The final MC for spruce should be between 8.0 and 9.5 percent MC.
Bonding and machining. The bonding is excellent. The wood is very tolerant even if the gluing parameters are not perfect. Machining is excellent as long as the tools are very sharp.
Stability. The wood is quite stable when the MC changes. It takes more than 4 percent change in MC to develop a 1 percent shrinkage in the width of the flat-sawn lumber (tangentially) and 10 percent change in MC at the 1 percent thickness (radially).
Strength. For balsam fir, the ultimate strength (MOR) is 9,200 psi; stiffness (MOE) is 1.45 million psi; the hardness is 400 pounds.
Color and grain. Fir is a straight-grained, odorless, uniformly colored white or pale white wood. Sapwood and heartwood are the same color and cannot be easily separated. Small, tight red knots are common and add character to the wood. A premium “knotty pine” look is easily achieved.