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Southern pine.


You could, literally, write a book exclusively about pine trees. This American conifer has a multitude of names, commercial and familiar, and an array of uses. Wood of the Month will devote this and two future columns to the ubiquitous pine beginning with southern pine.

Pine trees are evergreens that grow naturally in the northern hemisphere in all kinds of environments. It leads the world as the most important source of timber. Pines generally grow tall and straight, making them ideally suited for use as lumber. While there are roughly 100 species of pines in the world, some 65 species grow in North America and 36 are native to the United States.

Most southern pine lumber grows in the southern and south Atlantic states with the greatest production from Georgia, Alabama, Mississippi, Arkansas, and Louisiana.

Peter Kock is author of the two-volume book on southern pine called "Utilization of Southern Pines," (Agriculture Handbook #420). In his book described by many as the definitive treatment on the subject of southern pine, Koch lists the 10 species of pines known commercially as southern pine. The major species include: longleaf pine (Pinus palustris; shortleaf pine (P. echinata); loblolly pine (P. taeda); and slash pine (P. elliottii).

Koch's book includes the classifications of southern pine, physical properties, how it is processed and information on storing and machining. He said the 10 species known as southern pine have differences a botanist can detail, but that the trees produce very similar lumber. "You can see a variety of cows in the field such as Angus, Aberdeen and Hereford but when you see a T-bone steak on your plate it is pretty hard to tell which one it came from. Southern pines are like that," he said.

A readily treated wood

Jeff K. Easterling, treated markets manager for the Southern Forest Products Assn., said southern pine grows in 12 states throughout the southeastern United States. Easterling said southern pine is particularly suited for structural uses in the United States and is one of three readily treated pines. The other treated pines are ponderosa and red pine, although southern pine accounts for roughly 80 percent of the pine that is treated.

Pressure treated wood is wood that has been treated with chemical preservatives to protect the wood exposed to the elements, in contact with the ground or used in areas of high humidity. "Southern pine has long been a preferred species for treating because its unique cellular structure permits deep uniform penetration of preservative chemicals, making it immune to termites, fungi and micro-organisms. While most species must be incised or perforated with a series of small slits on the grain's surface to gain preservative penetration, southern pine is one of the few species that does not need incising," said Easterling.

There are three main classes of wood preservatives used today for pressure treating wood. Waterborne preservatives are used for most residential, commercial, marine, agricultural, recreational and industrial applications; are clean, odorless and paintable; and can be used for interiors and exteriors without a sealer. The most common of the waterborne preservatives is chromated copper arsenate or CCA. Other fixed arsenate compounds used to treat southern pine include ammoniacal copper arsenate, ACA, and acid copper chromate, ACC. Pressure treated wood can last for decades. The SFPA points to the ecological benefits of pressure treating wood. "Without pressure treated wood, an additional 226 million merchantable trees would be required annually to replace decayed or termite-infested wood products," said Easterling.

The uses of pressure treated lumber include: decks, boardwalks and bridges.

Easterling said he has seen a boom in the use of pressure treated southern pine. "A large portion has been used for residential uses as well as industrial applications. CCA-treated southern pine markets have had a dramatic upsurge since the early '80s. Changes in the end use of southern pine have caused changes in manufacturing processes. Current markets demand products with an improved appearance that are required for materials used in decking flooring and paneling. The industry has responded by adding special grades and emphasizing quality control," said Easterling.

Differences in retention levels

Treated southern pine is not all alike. The industry has developed standards for different levels of preservative retention keyed to the end use. The retention level is simply the amount of chemical preservative remaining in the structure of the cells when the treatment process ends.

Retention is measured in pounds of preservative per cubic foot of wood; the higher numbers face the most "harsh" conditions. For example, an above ground use would require a retention of preservative of 0.25 pounds per cubic foot while a marine or salt water application would need a retention of 2.50 pounds per cubic foot. Ground contact would need 0.40 pounds per cubic foot and wood foundation 0.60 per cubic foot.

Other uses and characteristics

The uses of southern pine also include pulpwood, which is converted by the sulfate process for use in manufacturing kraft paper, some fiberboard and insulation.

Also, a large percentage of the world's supply of resin and turpentine comes from longleaf and slash pine.

Southern pine has a sapwood that varies in color from nearly white to pale yellow to an orange white. Its heartwood ranges from yellow to orange to a pale brown. The book "Textbook of Wood Technology" which details the structure, identification, uses and properties of American and Canadian commercial woods, makes note that the yellow or hard pines of "southeastern and eastern United States cannot be separated on the basis of wood structure; in the trade, southern pine is usually marketed according to density."

The Southern Pine Marketing Council, a group underwritten by the SFPA and the Southeastern Lumber Manufactures Assn., publishes a southern pine use guide which covers the various lumber grades and standard size information, lumber storage tips, preservative information and design values.
COPYRIGHT 1991 Vance Publishing Corp.
No portion of this article can be reproduced without the express written permission from the copyright holder.
Copyright 1991, Gale Group. All rights reserved. Gale Group is a Thomson Corporation Company.

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Title Annotation:Wood of the Month
Author:Kaiser, Jo-Ann
Publication:Wood & Wood Products
Article Type:column
Date:Jun 1, 1991
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