Basswood (Tilia americana), also called linden, is a beautiful, fast growing tree reaching heights of 130 feet. Basswood trees have straight trunks, with most of the bole limb-free, thereby producing large volumes of clear lumber. The flowers are profuse and very aromatic, which has resulted in widespread planting of the tree in urban areas. The wood itself is creamy white, low in weight and strength, and without much obvious grain.
There are three commercially used species of basswood in North America: American basswood; Carolina basswood; and white basswood. The wood is so similar, that they are not separated in the lumber market. The natural range of American basswood is widespread, ranging throughout the area from southwestern New Brunswick to eastern North Dakota to North Carolina. Carolina basswood is found in southeastern U.S. from Virginia to Florida, west to Texas. White basswood is common in the Appalachian Mountains and the Cumberland Plateau region of eastern U.S. Due to potential staining problems if shipping lumber before drying, it owul dbe prudent to purchase basswood from sawmills and drying facilities in these growth areas.
If you have been to Europe and seen some of the beautiful religious paintings on wood, the wood used was basswood. In Europe, the wood is called lime. There are over 25 species of basswood in Europe.
Any "old time" architects and engineers (before CAD-CAM and GPS) will remember that their drafting tables were made of basswood. Basswood was also the preferred wood for surveying stakes, tripods, and other related equipment. Basswood, due to its freedom from odor and taste, also has been and continues to be the preferred wood for apiary (bee hives) supplies and other food contains. It has been and still is also the top choice for wooden Venetian blind slats.
Wood carvers also love basswood as its straight grain and low density mean easy cutting. This can be an important and profitable outlet for small pieces of wood that result from typical manufacturing; save the waste!
In my book (and for many people) the most important use of basswood is ... Rapala (R) fishing lures!
Processing suggestions and characteristics
Basswood is one of the lightest weight hardwoods in North America. Its density is about 25 pounds per cubic foot or about 2 pounds per board foot (BF), one-inch thick. A planed piece 3/4-inch thick at 7 percent MC will weigh under 1-1/2 pounds per BF
Basswood dries rapidly with little risk of defect development except for staining. If the logs or lumber are stored for any length of time at temperatures over 50F before drying begins, blue stain or gray stain is very likely.
Because many uses for basswood, such as Venetian blinds, require long, narrow, thin cuttings that must be flat, special attention must be paid to stress relief (or conditioning) at the end of drying. Specifically, conditioning must rapidly (half-hour if possible) achieve the desired humidity and be done at 170 to 180F. Uniform final MCs before conditioning are required to achieve uniform stress relief.
Shrinkage in drying is about 7 percent, which is higher than would be expected given its density.
Final MCs are often a little lower (5.5 percent MC) than for other hardwoods in order to increase the wood’s strength and avoid fuzzing in machining.
Gluing and machining
Gluing is excellent, with the wood’s softness making it very forgiving. Very low MCs and low density mean that pressure needs to applied ASAP after the glue is spread, or a starved joint is likely.
Basswood machines very well if tools are sharp. Dull tools or old (dull) sandpaper result in fuzzing. Low MCs are important to control fuzzing.
Basswood changes size by 1 percent if the moisture changes by 3 percent MC. This is a higher rate of change than many hardwoods, but basswood’s straight grain minimizes any warping that could occur if the moisture changes.
The strength (MOR) of basswood is 8700 psi, which is quite low. Hard maple is nearly twice as strong. Likewise, the stiffness is somewhat low; 1.46 million psi, compared to 1.8 million for hard maple. The hardness is 410 pounds compared to 1440 pounds for hard maple.
The nail and staple holding power and screw holding power are also low. On the other hand, splitting risks when nailing are very low.
Color and grain
The creamy white heartwood and sapwood are so similar in appearance (most of the time) that it is hard to tell them apart. The texture is very fine and the grain is indistinct. Due to variations in color from region to region and also when handling from forest to dry product is not perfect, staining can develop. Therefore, a contract for basswood should specify the color required to facilitate return of any off color material. (It would be prudent to include MC requirements and the need for freedom from stress or casehardening, as appropriate.)
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