Longleaf pine (Pinus palustris), also called fat pine or heart pine, is one of the four major species making up the Southern pines. It is the strongest of the four, the tallest (over 100 feet) and the most fire resistant.
While the tall, stately longleaf pine once covered 30 to 60 million acres of the southeastern U. S. coastal plain, 200 years of logging and land clearing have greatly reduced its range to 10 percent of the past acreage. The tree takes 100 to 150 years to become full sized and may live for 300 years. Needles are 8 to 18 inches long. Pine cones are 6 to 10 inches long.
A great deal of effort is being placed on protecting younger trees so there will be a supply of older trees in the future for the endangered red-cockaded woodpecker who uses the mature trees for nesting. The seeds are an excellent food source for squirrels, turkey, quail and brown-headed nuthatches.
Longleaf pines were a major resource for naval stores in the past (that is, resin or pitch before petroleum-based tars and derivatives were available). The timber was also used for heavy construction, railroad bridges and elevated tracks, floors and cooperage (barrels).
Present uses include floors and large lumber pieces and timbers, especially historical conservation and restoration, as well as typical construction uses. Some longleaf pine lumber and timbers have been salvaged from torn down old buildings and some logs from the bottom of lakes and rivers. There is very limited harvesting of old growth longleaf pine today.
Processing suggestions and characteristics
The density of longleaf pine at 12% MC is 37 pounds per cubic foot. This means that a kiln-dried 2x10x16 piece of lumber will weigh over 42 pounds. Loblolly pine, a common Southern pine, weighs 34 pounds per cubic foot. Eastern white pine weighs 24 pounds per cubic foot.
Longleaf pine dries very easily and rapidly. Shrinkage in drying to 10% MC is 5.2% tangentially (the width of flatsawn lumber) and 3.4% radially (the width of quartersawn). Drying temperatures should exceed 180 degrees for at least 24 hours to assure that the pitch is set so that the sap will not exude out when the wood is in-use.
Gluing and Machining
Gluing is difficult, in part due to the high resin content of the wood and in part due to the high density. It is suggested that the surface be freshly prepared and washed with a solvent to enhance gluing.
This wood is quite hard to machine due to its high density. Like all southern pines, it is common to have the hard, dense part of the growth ring pushed down into the softer fibers when planing, rather than cut cleanly. When the wood is then exposed to any moisture regain, the crushed fibers return to their original size and thereby push the dense fibers above the surface, causing a defect called raised grain. As with all dense wood, the tools must be very sharp.
Although the aroma of freshly processed wood is quite pleasant, the fine dry dust may cause dermatitis, allergic bronchial asthma, or rhinitis in some individuals.
The wood is fairly stable in use. It requires a 4% MC change to result in a 1% size change tangentially and 6% MC change radially.
The ultimate strength (MOR) is14,500 psi. The bendability (MOE) is 1.98 million psi. The surface hardness is 870 pounds. Comparable values for loblolly are 12,800 psi, 1.79 millionpsiand 690 pounds; for eastern white pine, 8600 psi, 1.2 million psi, 380 pounds.
Color and Grain.
The older trees produce lumber that us almost100% reddish heartwood. The second growth trees may have 2" wide yellowish-colored sapwood. The color contrast within an individual growth ring is high between the earlywood (light colored) and latewood (dark colored), adding character. The grain is fairly straight, except around knots and when compression wood is present.