| Cold-Bend™ hardwood undergoes extreme physical, longitudinal thermo-mechanical compression. There is no chemical treatment, or glues used in the process. Cold-Bend™ hardwood is solid hardwood that has been selected and milled to yield clear lumber. It is carefully controlled for moisture content. Cold-Bend™ hardwood is not modified in any way except for the extreme compression and the careful quality selection and moisture control required for its extreme bending qualities.
Wood used for compression must be clear and straight grained - essentially veneer quality temperate hardwoods (i.e. beech, ash, oaks, cherry, maple, walnut) . Softwoods and most exotics do not work in this process. Only about 20% of a good log is suitable for wood compression. After sawing from the log, the green, wet boards are partially dried over a period of a few months, then sawn and planed to the required dimensions.
The patented and trademarked Cold-Bend™ hardwood process begins by steaming the planks under pressure in a large autoclave. The hot, wet boards are then placed in the compression chamber of the Cold-Bend™ hardwood press, which compresses it lengthwise to about 75 to 85 percent of its original length, while maintaining the other dimensions. The wood is altered at the cellular level. You can think of the normally rigid cell walls as sliding into or folding over on themselves. Imagine a drinking straw, and a hospital straw, and you will get an idea of the difference between hardwood and compressed hardwood. You may think of the compression as producing a bellows effect in the cell walls.
Once removed from the press, the wood returns to about 10 percent of its original, trimmed length during a process called "Compression Resting". It is immediately set into a second press where the forces are allowed to equalize throughout the compressed planks. After compression and resting, the wood retains amazing flexibility, as long as it is kept moist, making it suitable for bending cold, by hand. The compression allows the wood to both stretch on the outside of the curve (something wood can't otherwise do) and further compress on the inside of the curve without backing straps, heat or steam. The wood is flexible until dried, so it can be bent onto or over a fixture while wet, then dried to fix the shape. The dried wood is rigid, and is identical to the original wood, except that by now it has probably taken on some cool new shape. About 5 to 10% of the original strength of the wood may be lost, insignificant in most applications, and usually better than other shaping methods like steam, lamination and sawing curves.
Cold-Bend™ hardwood retains its bendability for long periods as long as it stays moist. It may be kept for several months to a year or more by wrapping it in plastic wrap and storing it in a cool place. We have stored some compressed boards for 6 years now, and take some out for bending once in a while to see how flexible they remain. Certainly some capacity is lost if the wrap has punctured or cut and the wood looses moisture, but these moist boards retain amazing flexibility. Aged or old compressed wood can be somewhat rehydrated to increase flexibility if it hadn't been previously kiln dried. Compressed hardwoods should not be steamed, which causes the wood to loose much of its compression.
The minimum radius for bending is in the range of 5 times the thickness of the board, i.e. you could bend a 1" board to a 5" radius. Ash and Oaks have the best bending capabilities.
Maximum net production size is 3.5 x 6" x 100", but is more typically produced in planks that have thicknesses of 7/8", 1 1/8" and 1 3/4" x 6" wide x 100" long.
Cold-Bend™ hardwood is only manufactured in one location in the Americas - in Gig Harbor, Washington, by Fluted Beams LLC. Cold Bendable Compressed Wood is available in a range of species and sizes. There are a few presses in Europe and Asia, most of which are in furniture plants (picture Windsor chair backs), or supply furniture manufacturers. Fluted Beams LLC is the only wholesale or retail supplier of Cold-Bend™ hardwood worldwide to consumers, woodworkers, and production factories.
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