WoodSense: Spotlight on Purpleheart

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This article is from Issue 63 of Woodcraft Magazine.

A distinctive color makes it an ideal accent wood.

By Robert J. Settich
Technical consultant: Larry Osborn

Except for a handful of vegetables, flowers, and minerals, purple is one of the scarcest colors found on the planet. For that reason, it is no wonder that purpleheart (Peltogyne spp.) is the only commercial wood of that color, captivating woodworkers who scout for something eye-catching. Like other disctinctive exotic hardwoods, it holds a valued place in the woodworking project world. Although the lumber is not so expensive that similar largescale projects are prohibitive, two factors work against purpleheart. The first is the color. In small doses, purple projects positive associations, such as nobility, creativity, and peace. But in a large dose, a large purple cabinet, for example, the color purple can be overwhelming. The second factor: the wood changes colors over time.

It’s a fact that…

The full-sized reproduction of the 129' slave ship Amistad, which was launched in May of 2,000 in Mystic, Conneticut, featured a sturdy keel made of purpleheart from Guyana.

History in woodworking

Within its native range of Central and South America, purpleheart (sometimes referred to as Amaranth) has served as a common building material for applications such as dock pilings, boat decks, planking, bridge timbers, and even railroad ties. It excels in many of these uses because of its strength and natural resistance to decay and insects. In the United States, the first documented use of purpleheart lumber was for the 1928 installation of a library in the Lindsley mansion in the Berkshire Mountains, Massachusetts. Now that’s a lot of purple. Today, hobby woodworking projects made exclusively from purpleheart tend to be of small scale: bottle stoppers, pens, bowls, knife scales, and jewelry boxes. Woodworkers sometimes introduce purpleheart as an accent color in inlays and laminations. You find it in multi-species cutting boards.

Where it comes from

The genus Peltogyne encompasses more than a dozen species of hardwoods native to tropical rainforests. Brazil’s equatorial region of the Amazon River basin is a prime growing area, as well as Suriname and Guyana. Purpleheart trees grow from 100' to 170' tall, with trunk diameters up to 4'. It is not a threatened wood. Freshly harvested timber displays a dull gray purple and brown, with a creamy gray sapwood. Over time, the sapwood doesn’t change, but the heartwood transforms to a rich purple, and then dark brown.

Purpleheart

What you’ll pay

Online and specialty wood dealers sell purpleheart by either the piece or board foot. For example, one online retailer sells a 3⁄4 × 4 × 48" board for $26, while another sells purpleheart for $10.50 a board foot. Thinner and shorter boards are available. For instance, one specialty woodworking store sells a 1⁄8 × 3 × 24" board for $9.50 and a 1⁄4"-thick piece for $12.00. The thickest chunks of purpleheart will likely be bowl and spindle blanks. A 3 × 3 × 6" square, costs about $20. Expect to pay about $2 for either a 3⁄4 × 3⁄4 × 5" pen-turning blanks or a 11⁄2 × 11⁄2 × 3" bottle-stopper blank. A 4' × 8' sheet of paperbacked veneer will set you back $225. The lesson: shop around and factor in shipping costs with online dealers. Finally, while most purpleheart lumber is relatively straight-grained with uniformly distributed pores, you’ll sometimes find curly wood, which commands a premium price.

How to select the best stock

Lumber dealers identify purpleheart as Peltogyne, omitting identification of the many species grouped under that name. Therefore, you could encounter substantial color variations, ranging from wine-red to eggplant to true violet. So if your project is to require several boards, try to choose them in person. If that’s not feasible, acquire all of them from one dealer, requesting consistency of color throughout the order. Because of the changing color of purpleheart over time, visualize the wood in its eventual deep brown stage, not its purple stage, to avoid future disappointment. For the same reason, avoid laminating purpleheart next to a browntoned wood to maintain contrast.

Working purpleheart in the shop

Purpleheart presents a number of challenges in the shop. Because of the hard-to-detect interlocking grain, hand-planing, chiseling, and working purpleheart with carving tools can prove trying. Routing this dense wood can result in burning, which is hard to sand out, and gouging can unexpectedly occur when jointing. Purpleheart turns cleanly with sharp tools, and it sands well. As with other woods, work through a progression of grits to produce smooth results. If fastening purpleheart project parts with screws, drill pilot holes to avoid splitting. Avoid using nails, as they can sometimes bend when driven. Common woodworking glues work fine when bonding purpleheart in an assembly. However, because of the resins found in such tropical woods, a little prep work may be in order. To ensure a good bond, wipe freshly machined mating edges with acetone, lacquer thinner, or naptha until color no longer transfers to your cleaning cloth. Purpleheart responds to exposure to air and UV (ultraviolet) light that produce the unavoidable color shift. Employ one or more of these strategies to slow the process:

  • Use only film-building finishes, and apply several coats to minimize oxidation.
  • Apply waterborne finishes to darken the wood less than oil-based finishes; they won’t yellow with age.
  • If you prefer oil-based, consider one with a UV inhibitor.
  • Keep your project out of bright light, especially sunlight.


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