Woodsense: Spotlight on RedwoodComments (0)
This article is from Issue 40 of Woodcraft Magazine.
Long-lived lumber from California’s land of the giants
America’s coast redwood (Sequoia sempervirens) rates as nature’s plant giant, because it towers 350' or more. Yet given redwood’s height, it’s not a tall and lanky tree—a redwood felled in the early 1900s had a 26'-diameter trunk that yielded 344,000 board feet of lumber. The redwood is also the world’s second-oldest living thing. Ranking second only to the bristlecone pine, coast redwood specimens have been found that were close to 3,000 years old!
There are two other species in the redwood family, neither of which becomes commercial lumber. California’s giant sequoia (Sequoiadendron giganteum) grows only in about two dozen protected groves and at higher elevations than the coast redwood. China is the home to the third, the dawn redwood (Metasequoia glyptostroboides).
History in woodworking
Ever since it was first harvested in 1777 to build a mission in Santa Clara, California, redwood has been employed in construction for everything from exposed beams and posts to panels and siding. It’s also been relied upon in the past for large water tanks and vats, because natural chemicals in redwood’s heartwood resist water, insects, and decay-causing fungi, yet they impart no odor or taste to liquids. Today, it’s a favorite material for hot tubs. In and close to its growth range, redwood remains the favored species for grand homes, elegant outdoor structures, decks, fences, and furniture.
Where the wood comes from
As its name implies, the coast redwood only grows in a narrow coastal mountain range some 500 miles long from near Monterey, California, to Oregon. But it’s this mountainous habitat that provides the fastest growing of all conifers the rain and fog needed for moisture. And it’s interesting to note that commercial harvesting of redwood occurs on private lands in only the upper elevations of its range, representing about 10 percent of its growth area. The rest of the redwood forests are protected in parks and preserves.
Supplementing the natural supply, redwood from buildings, tanks, vats, and other structures is salvaged, resawn, and sold as recycled lumber. Because much of this recycled wood originated in larger, old-growth trees that yielded more heartwood with tighter grain, it is quite valuable.
What you'll pay
At a mill there may be several dozen grading designations for redwood lumber, but you needn’t know them all. Simply remember the following. For furniture and cabinets, choose from these kiln-dried “architectural” grades: clear all-heart, which is all heartwood (the most durable) with minor defects on one side; clear, with minor defects on one side, but includes sapwood; and B-grade, a mixture of heartwood with sapwood and some tight knots. Also available are less expensive, air-dried “garden” grades (construction heart, construction common, merchantable heart, and merchantable). Keep in mind that projects built on or near soil require using all heartwood. For projects not touching the ground, you can use lumber with sapwood.
Redwood also comes as flat grain (that actually looks wavy, but was sawn at an angle to the growth rings) or vertical grain (looks straight, but sawn across the growth rings).
As with other softwoods, redwood lumber is sold in nominal sizes, for example, 2×4, 1×6, and so on, in up to 20' lengths, yet the top grades carry a board-foot price. The closer you live to its source, the less you’ll pay for redwood. On the West Coast, the board-foot cost can be as low as $3; on the East Coast it may be nearly double.
Redwood plywood isn’t available. However, you can find exquisite (and quite expensive) veneer cut from redwood burl and some turning blanks.
How to select the best stock
Select redwood lumber first for intended use, and then for appearance. If you don’t need decay resistance and durability in contact with the ground, use less-costly heartwood with sapwood grades. You might, though, prefer the look of top-grade vertical grain for cabinets and furniture.
Keep in mind that redwood heartwood looks salmon pink when first cut, but after exposure to air and sunlight it changes to dark red. Its sapwood remains white. Outdoors without finish protection, redwood heartwood eventually turns a silvery gray.
Working redwood in the shop
Although light and straight-grained, redwood has excellent structural strength and generally machines quite well. Yet lumber from young second-growth trees and lower grades does tend to splinter and split. Also, the wood is basically softer than white pine, so it’s easily dented. With that in mind, follow these suggestions:
- Planing, ripping, routing, and jointing. In planing, take only a shallow cut to avoid chipping and tear-out. You’ll have no problem ripping redwood, but use a fine-tooth blade for crosscutting. Remove no more than 1⁄16" at a time in jointing. And be sure to use a backing board when routing across grain.
- Sanding. The contrasting hardness/softness of earlywood versus latewood can result in a wavy surface when hand-sanding, so always use a sanding block.
- Assembly. All glues work well. To avoid splitting, drill clearance and pilot holes before driving screws. For outdoor projects subject to heavy use and abuse, rely on the joint strength provided by nuts, bolts, and washers. To prevent black stains, use non-corrosive fasteners.
Deciding on the right finish
Redwood readily accepts all interior finishes. Outdoors, however, redwood needs the protection of specially formulated penetrating oils with ultraviolet light (UV) inhibitors. Without UV protection, clear film finishes will quickly break down after prolonged exposure to direct sunlight. Another outdoor solution is semi-transparent stain. This adds color without completely masking the wood grain.
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