One of the most magnificent trees of the Southern swamps and bayous is the cypress tree with its large diameters, its towering branches and its knees sticking up out of the water. Technically, this tree is officially called baldcypress (Taxodium distichum). Common names include baldcypress, pond cypress (a special variety found in Florida), tidewater cypress (lumber from pond cypress tree), and sinker cypress. Cypress, when grown in wet conditions, produces roundish, several inches in diameter, extensions of the root system that will protrude vertically many feet into the air. These leafless protrusions are called "knees" and apparently help the roots obtain oxygen, even though the tree roots are submerged.
Cypress grows in wet sites from Delaware, along the coastal areas through Florida to Texas and up the Mississippi River Valley. Trees often will be more than 500 years old, with diameters being many feet. However, the large trees that are centuries old (called "old growth") are now rare and much of the cypress harvested today is "second-growth." There is also an active supply of old growth cypress that has been salvaged from earlier construction projects. There are also some firms that are harvesting century-old logs from the bottom of lake and rivers to provide excellent wood. During the mid-1900s, with an active program to drain swamps and bayous, reproduction of cypress trees was great affected; volumes of good timber today are small, but restoration of wetlands is encouraging more growth.
Although cypress is a conifer with needles for leaves, it does loose it needles every year in the winter. The wood itself is noted for very high natural insect and decay resistance, especially the "old growth" material; second growth does not have this same high level of natural protection, but still provides good protection from insects and decay. The natural preservative is a chemical called cypressene.
Cypress sometimes, while growing, is infected by a white fungus that leaves white pockets of rot. Although the fungus dies when the log is sawn into lumber and dried, the resulting wood with its small (approximately 3/8-inch diameter and 1 inch long) holes, is termed "pecky cypress" and is highly desired due to the beautiful characteristics.
In the past, cypress has been used in outside locations for piers, docks, stadium seats, greenhouse construction, caskets, porches, boats and ship construction, shingles, cooperage and outdoor furniture. Over 100 years ago enormous dugout canoes of cypress carried 20 to 30 Native Americans on trading voyages across the Straits of Florida to Cuba . Cypress is also called "eternal wood" because it lasted so long; hollowed logs installed in 1798 as water pipes were still working in 1914 when they were replaced and shingles have been found that are over 250 years old.
Processing suggestions and characteristics
The wood has a density of about 31 pounds per cubic foot at 10 percent MC. A thousand board feet, 3/4-inch thick, will weigh about 1900 pounds at 10 percent MC. The density is higher than many softwood species.
Drying is difficult, compared to the pines, due to the tendency to develop surface and end checks. The wood is also known to develop water pockets–small wet regions within a piece of lumber (perhaps 20% MC) while the rest of the piece is 10 percent MC.
Shrinkage in drying is under 5 percent. This is quite low.
Extreme care must be exercised to avoid over-drying, as the wood becomes brittle and machines very poorly when under 9 percent MC. Final moisture contents for cypress should be no lower than 10 percent MC, which is higher than most hardwood lumber.
Gluing and Machining.
Cypress machines very well if not over-dried. The tools must be quite sharp to cut the wood fibers cleanly and avoid pushing the hard latewood portion of the annual growth ring into the softer sections. If indeed dull tools are used, then, when the wood is subject to regain of moisture, the grain will pop up and become corrugated–it is called raised grain. It is critical to avoid machining pieces under 10 percent MC as they will machine as though the wood was very brittle.
Cypress is easy to glue, although the waxiness does mean that surfaces should be freshly prepared. The softness means that the wood is somewhat forgiving, if gluing conditions are not quite perfect.
Cypress is subject to small size changes when the MC changes–about 1 prcent size change running across the grain parallel to the rings (tangentially) for each 5 percent MC change, and about 1 percent size change across the rings (radially) for each 8 percent MC change.
Cypress is medium in strength and stiffness. The bending strength (MOR) averages 11,000 psi. Hardness averages 560 pounds. Stiffness (MOE) averages 1.44 million psi. These are considerably higher than Ponderosa and white pine; they are close to red and radiata pine values.
Color and Grain.
The sapwood is white; there is only a little sapwood in a log. The heartwood is light yellowish brown, but at times can be somewhat darker, even chocolate brown. The growth rings have medium color and density contrast–not as striking as most pines. This makes for durable painting. The wood does have a slight waxy feel and this oiliness can make painting difficult. A prime coat that contains benzole is suggested. Many lumber users want rough-sawn surfaces; saw blades may have to be "poorly" sharpened to accentuate this type of surface.
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