A recent news article about the famous Antarctic explorer Sir Ernest Shackleton caught my eye. Apparently, the search is on to find the Endurance, his ship that sank during his infamous Antarctic expedition in 1915. The Endurance was reputed to be the strongest wooden ship ever built. In addition to a frame made of oak, the ship’s hull was clad in Greenheart, a wood well known in the world of marine architecture for its strength and durability.
Greenheart is a tree native to northern South America with Guyana the prime exporting country. It is a medium sized tree approaching heights of 100 feet with diameters of 1.5 to 2.5 feet. The wood is hard, heavy, dense and is purported to be the world’s stiffest.
Greenheart is also extremely durable. The same chemicals that give it its distinctive colouring also provide protection against fungi and insects. It is also resistant to marine borers, organisms that attack the hulls of wooden boats. While Teak is usually considered the gold standard of marine timbers, Greenheart is a very close second.
Given these qualities, Greenheart is used in all sorts of marine applications. Shipbuilders used it for decking, hull cladding, engine mounts stern posts, etc. It is also used where strength is paramount such as docks, pilings and breakwaters. The fine woodworker can make use of Greenheart in turned objects such as pool cues and fishing rods. Fans of intarsia (the creation of images using cut pieces of wood) appreciate Greenheart as one of the few woods with a green colour.
The wood itself is straight grained, occasionally presenting as interlocked. It has a medium to fine texture with a natural luster. The heartwood tends to be an olive green with occasional dark streaks running through it. The sapwood is a paler yellowish green that is not distinguishable from the heart.
Working with Greenheart can be difficult due to its density. It will blunt tools quickly. Straight grained pieces will plane nicely, but the interlocked pieces are prone to tear out. Carbide tools are a must when machining this wood. Backing should be used when Greenheart is crosscut as the wood will tear when the blade exits the cut.
The wood turns easily, leaving turned surfaces with a high luster that needs little finishing. Given its density, Greenheart can be difficult to glue. You should avoid excess clamp pressure to prevent glue squeeze out and starved joints. Nails and screws should be predrilled. It finishes well taking waxes, oils and film finishes with comparable ease.
Some woodworkers have reported allergy-like reactions when working with Greenheart, typically dermatitis or some breathing issues. These health problems are rare but can increase with repeated exposure. Wearing a mask and keeping dust under control is a good idea.
Splinters can also be a concern since they can become infected. Handling rough lumber should be done with care.
Greenheart is rarely imported into Canada in lumber form. I’ve only seen it as offcuts with ragged edges. The probable origin of these offcuts is an interesting story. Greenheart is a wood that cleaves easily. So easily, that pieces can ‘explode’ off the sawn part of the log as it exits the saw blade. Flying pieces of Greenheart have even penetrated the metal roofs of some sawmills. Sawyers will wrap the Greenheart log with chains to restrain these errant pieces, some of which likely made it into an offcut bin after the sawing process was finished.
Greenheart is not on the CITES list and there is some debate on its status with the IUCN. If you do come across some, it will likely be in short pieces suited for turning and other small projects. Some people are beginning to import Greenheart as a material for exterior decks. Given its durability and outstanding weathering properties it could give Ipe and other exterior deck species some competition.
Unfortunately, Shackleton’s Greenheart clad Endurance couldn’t withstand the crushing forces of the Antarctic ice. I expect that any Greenheart boards found at depth will still be sound, a true testament to its durability. I doubt that any woodworker will be using Greenheart in such a demanding environment; but, for an intarsia or turning project, Greenheart is an excellent choice. Just watch for splinters!