Here is a discussion of guitar woods in general, with specific attention to the woods used in the Hirade K5.
Thuja plicata: North American western (Pacific) Red Cedar
Antonio de Torres in the 19th century demonstrated that the soundboard is almost entirely responsible for the sound of a guitar (he built a paper mache body for his experiment!). A solid wood soundboard, almost always in two bookmatched pieces, thus seems a minimum requirement (newer methods involving modern composites are outside the budget and the tradition). Red cedar from western North America and European or North American spruce are the most used soundboard woods. Red cedar is not a true Mediterranean cedar, but rather a member of the evergreen Cypress family. It has an enjoyable scent and a warm reddish-tan appearance. Compared to spruce, cedar has the same type fine straight grain, is softer and thus more easily dinged, is less dense (SG 0.32 vs. 0.40 for spruce; hardness 350), is able to reach its full resonance potential more quickly (months vs. years), is more responsive to light playing even when new, and is more dimensionally stable (less susceptible to changes in humidity and temperature). On the other hand, spruce, when played-in, is said to have a clearer, more analytical sound, and more headroom for producing large volumes of sound in response to heavy playing before the soundboard ‘saturates’ and sound deterioration sets in. A cedar soundboard is said to add its own color to the sound, a warmer, darker, and less direct tonality than spruce, but still with good clarity and openness.
The K5 utilizes an exceptionally fine grade of cedar with straight, uniform grain measured at 24 grain lines per inch.
Acacia koa: Hawaiian koa
Rosewood is the standard hardwood used for classical guitar bodies. Maple and mahogany are also sometimes seen. The K5 explores an alternative, Hawaiian koa. Instrument-grade koa heartwood has a warm ginger color capable of a highly lustrous finish. There is a dramatic, translucent, 3-D effect from highly-figured (flamed/curly) grain, although select grade’s simpler appearance has its own appeal. At its best, koa ‘i’o ‘ohia (hard ohia-like grain) is an open-pored hardwood (max. SG 0 .65, hardness 1220), about 80% as dense and hard as rosewood, but more stable and consistent. Its mechanical properties rank it just above black walnut in hardness and density.
Compared to rosewood, a brighter, slightly less round (bell-like) tone obtains from koa (less dense implies less reflective), with good projection, even, long sustain, and even response across the pitch range (less bass- and treble- emphasis than rosewood). The K5 has red-highlighted, ivory-colored body bindings.
Swietenia macrophylla: tropical Amer. mahogany
Mahogany is the standard choice for most classical guitar necks in this class, and when finished and cured to its customary reddish tint, visually blends well with the koa body. Mahogany is yellow-tan to red-tan, stable, straight-grained, open-pored hardwood (SG 0.52, hardness 800), less dense and hard than maple, strong as oak.
A koa-bodied guitar with cedar soundboard and mahogany neck uses the lightest available components typically used for each area, producing a relatively light guitar requiring less effort to handle and play.
Diospyros crassiflora: African ebony
Takamine’s web archive lists the K5 with a rosewood fingerboard, although this K5 appears to have an ebony fingerboard. The Takamine original K5 spec sheet lists an ebony fingerboard, and Takamine confirmed that a 1995 K5 has an ebony fingerboard (one of the hardest, densest woods; SG > 1.0, hardness 3200). It is black with a few hints of brown. Rosewood is the principal alternative fingerboard material, sometimes ebonized to resemble ebony. Rosewood is customarily considered less desirable than ebony, for aesthetics and structural reasons. Rosewood vs. ebony is sometimes considered the distinction between amateur and professional guitars, but the more oily rosewood has some advantages in resistance to checking. Either is sufficiently durable on a nylon-stringed guitar.
The finish protects the wood and adds a three-dimensional luster to beautify the wood’s appearance. But thick coats of finish can alter the tonewood properties. The K5 is finished in gloss poyurethane and appears to be quite thin.
Dings in the finish can be repaired by filling with thin cyanoacrylate (super glue); then level, sand, and buff. Dings that mar the wood itself may be restorable by removing the finish over the ding, covering with a wet cloth, and carefully heating with a soldering iron to swell the dented spot. Then refinish as above.
The K5 uses rosewood for the bridge under a bone saddle, and has a koa veneer applied to the mahogany peghead face.
Wood Sources (Green Considerations)
The aesthetics of solid wood need to be balanced against the environmental benefits of veneers/laminates, particularly when endangered hardwoods are involved. Brazilian rosewood, Hawaiian koa, Ceylon/African ebony, and Honduran mahogany, are currently afforded CITES endangered status (UN Convention on International Trade in Endangered Species). Export restrictions in countries of origin mean new supplies in the US, Europe, China and Japan should be suspect as illegal in origin.
Takamine is not yet advertising support for the international Forest Stewardship Council (FSC – the principal international NGO in wood source accreditation). The Japanese, although enlightened about preservation of their homeland forests, are ‘competitive’ when obtaining wood from other countries.
Gibson and Martin are US guitar manufacturers that support the FSC. It is currently difficult for manufacturers to get quantity of certified tonewoods, so their early-adopter role is doubly appreciated. Unfortunately, neither Gibson nor Martin make a classical guitar of the Hirade class. Luthier Merchantile, a US supply house, offers a limited assortment of FSC-certified alternative tonewoods, as does FSC-booster North American Wood Products. Many lumber supply companies are now stocking FSC-certified lumber.
Koa typically has a warm honey color, sometimes with dramatic flamed/curly grain, and has an enjoyable scent.
Cut Koa Log
Koa trees may be making a comeback in Hawaii where they are particularly prized. Both in publicly-owned ‘preserves’ that have been previously logged of all koa with commercial value, and on private for-profit plantations, re-forestry of tens of thousands of acres has been proceeding for the last 30 years. Yet it may be a couple of decades before quantities of the slow-growing certified plantation koa will be commercially available. Hopefully, none will be available from re-forested ‘preserves’.
Koa Crown Detail
The immediate future of koa is still under pressure and forests may continue to decline because of its high value and restricted supply. Continuous pressure is exerted by commercial interests to harvest ‘dead and dying’ koa trees on public lands. Perhaps if one is planning to cut a tree down, in some sense it is already dying.
Of all the woods in the K5, only the Red Cedar is plentiful. Red Cedar trees grow all over the northern Pacific coast of North America.