Jack pine's knotty appearance worth considering for furniture
By Gene Wengert
Jack pine (Pinus banksiana) is found in northeastern North America, ranging from Nova Scotia to the Rockies, south to Minnesota and eastward to Maine. It grows further north than any other pine in North America The U.S. Forest Service estimates that 99 percent of the jack pine in the U.S. is in the Lake States (Michigan, Minnesota and Wisconsin); in Canada, most is in Ontario. Other common names include blackjack pine, scrub pine and pin de Banks.
Jack pine is a rather small tree, reaching heights of 30 to 65 feet and seldom much over 16 inches in diameter. The stem is often not very straight. Branches are frequent. As a result, jack pine logs are not going to yield much clear, high grade lumber; rather knotty (but the knots will be tight) is more common. In fact, jack pine has very dramatic red knots that certainly making it worthwhile to consider this wood for knotty furniture or cabinets.
This species is thought to be the only species that the endangered Kirkland’s warbler will nest in. A mature stand of jack pine creates an acid soil due to needle fall, which makes the understory ideal for wild blueberries. In the past, wildfires would burn a stand of jack pine, but the heat would release the seeds from the cones and within weeks a new forest of jack pine was beginning. (This characteristic of a species is called a pioneer species.) As a result, this species would be most common in pure, even aged stands. With the elimination of wild fires and with the interest in planting red pine, the jack pine forest is declining in volume.
Native Americans used jack pine for canoe frames. Today, rustic paneling, cabinetry and furniture stock should be reasonable markets, if properly sawn and dried. Other uses include local construction, shipping containers, pallets and posts. In many lumber markets, jack pine is included along with other pines that it grows with, including red pine.
Other notable properties, in addition to its appearance, are that jack pine is relatively stable when the RH changes, is moderately light in weight and is moderate in strength.
This wood has not been widely used for middle or high quality uses. Yet, it does have some natural beauty and character with its knotty appearance.
Processing suggestions and characteristics
Density. The sapwood of jack pine is nearly white, while the heartwood is light brown to orange. The sapwood may make up one-half or more of the volume of a tree, so white-colored sapwood lum-ber with red knots is common, as well as is mixed sap and heart pieces. The wood has a rather coarse texture and, as mentioned, is somewhat resinous if not dried properly. The aroma is en-joyable.
Color and Grain. The density of jack pine is about 38 pounds per cubic foot at 10 percent MC. This means that a dried piece of lumber 1 inch x 6 inch x 10 feet (actual size ¾ inch x 5-1/2 inch x 10 feet) will weigh 11 pounds. This is over 20 percent heavier than eastern white pine, but is close to red pine.
Drying. Drying is easy and fast, but warp (due to compression wood and crooked stems) must be con-trolled using good stacking practices and even weights on the tops of piles. Avoid slow drying to help keep lumber flat. Drying temperatures should exceed 160F for 24 hours to set the pitch and thereby avoid resin exudation in the final product.
Gluing and Machining. Gluing of the wood is fairly easy, although the knots themselves will be harder to glue. Resin exudations will interfere with gluing if the pitch is not set in drying. Machining is moderately good. Certainly sharp tools are suggested. Avoid drying under 9.5 per-cent MC at all costs, as drier wood machines poorly (chipped grain, planer splits, etc.).
Stability. Jack pine is a little more stable than most species; jack pine requires a 5 percent MC change (or greater) for a 1 percent size change in the width of flatsawn lumber, and 8 percent MC change in quartersawn stock.
Strength. The strength (MOR) of jack pine is 9900 psi; the stiffness (MOE) is 1.35 million psi; and the hardness is 570 pounds. Corresponding eastern white pine values are 8600 psi, 1.24 million psi, and 380 pounds. In other words, it is considerably stronger, stiffer and harder than EWP. One area of concern is that jack pine is liable to split when nailed near the end of a piece. Pre-drilling holes will eliminate this tendency.
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