This is a simple, concise, and somewhat non-technical description of common woods used to make Ko’olau instruments.
You will notice terms such as density and specific gravity. Density ratings are the weight per given dimension, in this case, per foot. Wood is composed mostly of hollow, elongated, spindle-shaped cells, arranged parallel to each other along the trunk of the tree. Properties of wood, such as bending, crushing, and hardness depend on the DENSITY of the wood, thus heavier woods are generally stronger. Wood density (weight per foot) is determined by the relative thickness of the cell wall. An example of two woods, both technically “hardwoods” is Koa, with a density of 41 pounds per foot, and Kula (Prima Vera) with a density of only 28 pounds per foot. Thus the relative thickness of cell structure in Koa is thicker and thus heavier than Kula.
Another method of determining characteristics of woods is a term called Specific Gravity. This is the ratio of the density to water. In other words, since Koa has a specific gravity (s.g.) of .55, this means that it is .55 times as dense as water. Whereas rosewoods and ebony woods have a specific gravity of .85 to 1.09, or about as dense as water.
In practical and useful lutherie (guitar and ukulele building) terms this usually translates that light and less dense woods will produce a more open and “light” sounding tone, as opposed to heavy woods with deep resonance. And then some woods have the best of both. It should be noted that when a “soft wood” namely spruce, cedar, or sequoia redwood is added as a top wood, characteristics are completely changed, as over 90% of tone and volume are determined by the top.
We often explain to customers that one wood or combination of woods is not better, but instead just different.
In addition to properties of specific woods, below you will see a few examples describing tone and volume that results when certain woods used for backs and sides are combined with traditional woods used for tops, or soundboards, such as Spruce, Cedar, and Sequoia Redwood. Often this causes more confusion and we are often asked “what’s best” … but again, it’s not a what’s best decision, but instead, what sound is preferred. Most players, especially after becoming serious about guitar, ukulele, or any stringed instrument end up owning several instruments with a variety of combinations of woods.
One final thought on wood combinations. Often, entire instruments are made of the same type of wood. In these cases, the type of wood used is resilient enough (flexible), to allow the top to freely vibrate. This combination produces a softer, more muted tone, but sweet. But if it’s not done right, namely correct wood thickness, the sound can be dull and thin. The most common woods used for the entire body are ones with the lowest density, such as Koa, Mahogany, Kula, ‘Ula, Ash, and Acacia.
All instrument grade woods, regardless of density and specific gravity must be cut correctly. For all of our instruments, we always cut logs by a method called quarter-sawn (cut from the log a certain way to produce better stability and tone) and kiln dried. We hand pick each log or board to insure the highest quality instrument available.
Here is a listing of woods used for Ko’olau Instruments:
Ko‘olau and Pono Instrument Woods
Wood Density lbs/ft Specific Gravity
- Ash, Tropical (Fraxinus Uhdei) 32 .47
- Cedar, Western Red (Thuya Plicata) 23 .32
- Ebony, Macassar (Diospyros celebica) 68 1.09
- Koa (Acacia Koa) 41 .55
- Kou (Cordia subcordata) 45 .57
- Kula, Gold Tree (Tabebuia donnel-smithii) 28 .45
- Mahogany (Swietenia Macrophylla) 34 .54
- Mahogany (Swietenia Mahogani) 40 .64
- Mango (Mangifera indica) 38 .57
- Maple (Acer saccharum) 45 .72
- Myrtle (Umbellularia californica) 53 .85
- Pheasant Wood (Cassia siamea) 50 .75
- Port Orford Cedar (Cypress) (Chamaecyparis lawsoniana) 30 .48
- Rosewood Brazilian (Dalbergia nigra) 53 .85
- Rosewood East Indian (Dalbergia latifolia) 53 .85
- Sequoia Redwood (Sequoia sempervirens) 26 .42
- Spruce, Sitka (Picea sitchensis) 27 .43
- Spruce, Engelmann (Picea engelmannii) 24 .41
- Spruce, Appalachian Red (Picea Rubens) 26 .42
- Acacia (Acacia Preta, Acacia Melanoxylon) 42 .54
- ‘Ula Wood (Toona australis) 28 .35
- Walnut (Juglans nigra) 38 .50
Below is a description of each wood:
Mahogany – Two different types of Mahogany are used in furniture and instrument building. Both are becoming rare due to over harvesting. The most common Mahogany is Swietenia Macrophylla, popularly known as Honduras Mahogany, although now known as Tropical or South American Mahogany, since very little is harvested from Honduras. We use this type of Mahogany exclusively for our necks due to its strength, light weight, and stability. This species of Mahogany is relatively light, reddish-brown, and open grained. Weight is 34lb/ft and .54 specific gravity.
The other Mahogany we use is Swietenia Mahogani, or commonly named West Indian Mahogany, Spanish Mahogany, or Cuban Mahogany. This type, the West Indian Mahogany is more expensive due to being considered commercially extinct, however over 100 years ago this Mahogany, Swietenia Mahogani was planted here on Oahu. Although we have relatively few Swietenia Mahogani (or as we call it Hawaiian Mahogany) on Oahu, on occasion we are able to acquire this rarely harvested lumber. Our cost of acquiring this lumber is higher than most Koa. Hawaiian Mahogany is a beautiful red-brown color, but more dense and closed grained than the more common Swietenia Macrophylla. As compared to Swietenia Macrophylla, Hawaiian Mahogany (Mahogani) is slightly heavier and more dense. Weight is 40 lb/ft and specific gravity is .64.
Koa – Acacia Koa. The most prized, revered woods of Hawaii, and now throughout the world. In Honolulu, beautiful architecture, carvings, and furniture made of Koa can be found as a legacy of Hawaii’s mass deforestation of the 1800’s. Even today, Koa is still the preferred wood, and in this case, for musical instruments. It should be noted that many other species of woods throughout the world closely resemble Koa, and now are being marketed and sold as Koa.
Koa has similar properties to that of Mahogany, though slightly heavier in weight and greater in density, but like Mahogany it produces warm and sweet bass and treble tones, and adequate volume. Weight of Koa wood is approximately 41lb/ft and the specific gravity is .55.
Although most Koa instruments have top woods also made of Koa, we also combine Koa sides and back with a softer top soundboard such Spruce or Cedar (or Redwood). On all of our Koa instruments we use the most beautiful cuts available, the higher the model, the more curly and quilted the grain.
Hawaiian Ash – Otherwise known as Tropical Ash or Shamel Ash (Fraxinus Uhdei) – a blonde hardwood growing throughout the Hawaiian Islands, however Hawaii Island (the Big Island) is the only island with a significant volume of saw timber at present. Both sapwood and heartwood are both blonde, with little difference in color. Hawaiian Ash has a beautiful, fine textured grain with attractive figure similar to White Ash, but much lighter in weight and density. Weight is 32 lbs per cubic foot and specific gravity is .50 (similar to Swietenia Macrophylla (commonly known as Honduran Mahogany). Tone and volume are excellent.
As a side note: due to availability and the need for sustainability, we are now using uncommon and untraditional woods harvested in the Hawaiian Islands. And they are actually proving superior in many ways to traditional Koa, Mahogany, and Rosewoods. In many of our tests we have been surprised at the increased tonal range and volume from ‘Ula and Ash. Both can be used as top wood, or as back and sides and combined with spruce as a top wood. We will continue to search for and test new woods in order to protect our fragile Hawaiian Island eco-system.
Ebony – various species are used in instrument building. Both African and Asian ebony wood is used for fingerboards and bridges. Ebony is dark black and shades of black, very heavy and very dense. The most common ebony we use is Macassar Ebony, a very rare ebony from the island of Sulawesi or Celebes as the Dutch called it during their reign. Macassar Ebony is 68 lb/ft in weight, and specific gravity or density is 1.09.
Macassar Ebony has similar dark black colors to the more common and less valuable African Ebony. But it additionally has stunning chocolate and light brown coloration. Truly a beautiful wood. And the most rigid and stable of all ebony woods. A rare and prized wood primarily for fingerboards and bridges. Too dense to be used as a topwood, it can be used for backs and sides, but often combined with spruce, cedar, or Sequoia Redwood. Tonal characteristics are similar to Rosewoods, but due to the density of Macassar Ebony, both treble and bass have more clarity.
‘Ula – “Toona Australis” Australian Red Cedar, also called Toon or Indian Mahogany. Harvested on the Big Island of Hawaii. Rich reddish-brown in color, thus named ‘Ula, the Hawaiian word for red. In the past it was nicknamed “Red Gold” due to it’s highly valued wookworking properties. Grain patterns are not exceptionally dramatic, but tonal properties are amongst the best of all tone woods. Similar to mahogany in weight and density at 28 lb/ft and density is .35 specific gravity.
Kolohala – Cassia siamea, Commonly known as pheasant wood. This very rare, valuable, and stunningly beautiful wood produces shades of light to dark brown with fine black grain, which very much resembles the feathers of our local Hawaiian pheasant. Kolohala is a relatively heavy and dense wood. Weight is 50 lb/ft and density is .75 sg
Kula – (Tabebuia donnel-smithii). Kula means golden, and this wood has the most beautiful golden laced grain.Locally the tree is also called the Gold Tree, not because of the golden wood, but because, at certain times of the year the tree is full of beautiful yellow flowers. Elsewhere in the world, this species of tree is called Prima Vera. Tone and volume are excellent, with a perfect balance of bass and treble. Overall appearance of a completed instrument is a beautiful blonde color. Kula wood is approximately the same density of Koa, but slightly harder. We often combine this wood with Spruce for color uniformity. Weight of Kula wood is 28 lb/ft and density is .45 sg.
Milo – (Thespesia populnea) pronounced (me-low), a highly respected wood throughout Hawaiian history. Rich red and brown colors with a delicate lacey grain. To the ancient Hawaiians MILO and a wood called KOU (now replaced by KOA as the most common Hawaiian wood) were the most valuable and colorful woods used for furniture, canoes, paddles, and bowls. MILO has proved to be an excellent stringed instrument wood, producing deep resonant bass tones. Combines well with top woods such as Spruce, Cedar, and Sequoia Redwood. 39 lb/ft density and .55 specific gravity.
Rosewood – There are any different types of Rosewoods are grown throughout the world, the most common being known as Brazilian and Indian, but many different Rosewoods grow in South America and Asia. They are all similar in that they are very hard and dense, producing deep bass resonant tones. This wood is never used as a top soundboard, so when combined with tops such as Spruce, an excellent balance of bass and treble, and good projection is achieved.
Indian Rosewood (Dalbergia latifolia) or Brazilian Rosewood (Dalbergia nigra) Both species have have approximately the same weight of 53 lb/ft and specific gravity of .85Both very high quality tone woods. New cut Brazilian Rosewood is no longer available, however we have acquired environmentally salvaged, legal remnant wood, at least 30- to 50-year-old lumber, with spectacular beauty and resonant tone properties. And another beautiful Rosewood species that we use is Dalbergia Palissandre, which is very similar to Indian Rosewood and grows in Indonesia.
Maple – A very hard, dense, pale yellow wood often selected for a sharp, clear, and pronounced projection. Although less resonant bass than rosewoods, maple is “clean sounding” without muddy overtones. Almost all jazz guitars, mandolins, and violins thoughout history have maple for back and sides. However due to its density a “soft” wood such as Spruce should be used for the top. Maple weight is .45 lb/ft and .72 specific gravity.
Myrtle – “Umbellulria Californica” – Although this is not a locally grown hardwood, but imported from Oregon, we were so impressed with its beauty and tonal properties, we decided to include it in our line of available body woods. Myrtle has been used by well known guitar makers for many years. Also known as Oregon Myrtle, Laurel and Bay Laurel, this wood almost reminds us of a rare Koa wood known as “white Koa” with similar grain patterns and blond to light brown colors. Also, as with Koa, each piece is unique, with different colors and grain patterns. Exceptional bass, treble, and projection, Myrtle combines qualities of Rosewood, Mahogany, and Maple. In other words, it’s considered by some to be one of the best tone woods for stringed instruments. Weight is 53 lb/ft and density is .85 specific gravity.
Walnut – (Juglans nigra) Walnut has always been a precious wood throughout the world for furniture and guitarmaking. Although we do have walnut trees growing far up the slopes of the island of Hawaii (named the Big Island), walnut has rarely been used for ‘ukuleles. One Walnut tree can bring over $50,000 for fine woodworking. The sample photos are a walnut wood that exhibits the most figured curly grain ever seen in this type of wood. The finish on this sample is a satin lacquer, but still shows the unusual and beautiful grain patterns. The tonal properties of walnut are easiest to describe as similar to Brazilian Rosewood. Deep and rich bass resonance, and of course, combined with Spruce or Cedar topwood for clean mids and treble tones. Weight 38 lb/ft and specific gravity is .50.
Acacia – (Acacia Preta, Acacia Melanoxylon) – a beautiful wood growing throughout Polynesia and Southeast Asia, but originally from South America. Sometimes called the “Rain Tree” or “Golden Rain Tree.” The term Rain Tree is derived from the fact that the leaves close or fold during rain or limited light, thus allowing moisture to reach the ground under its beautiful, umbrella like canopy.
Various Acacia species grow throughout the Hawaiian islands, the most notable being Acacia Koa. All have beautiful color and grain patterns. Acacia woods are now becoming popular in guitarmaking. Being in the same family as Hawaiian Acacia Koa, Acacia Preta is sometimes mistaken for Hawaiian Koa (and in fact, sometimes unscrupulously sold as Koa). The color and grain patterns of Acacia Preta, along with a similar density and weight has made it a popular alternative to the limited and endangered supply of Koa.
But what is important is that Acacia Preta is in abundant supply and not endangered with exploitation or deforestation. May be used for tops, back, and sides, or combined with Spruce, Cedar, or Redwood. Weight is 42 lb/ft and .56 specific gravity.
Sitka Spruce (Picea Sitchensis) – creamy, white to light brown colored top wood. Preferred for it’s strength and tough elasticity. Due to its stiffness it is one of the most desireable soundboard woods. 27 lb/ft, .43 sg.
Englemann Spruce (Picea Engelmannii) – very similar to the high quality European or German Spruce, but more economical. Beautiful ivory color and sheen, softer than Sitka , similar to Western Red Cedar. 24 lb/ft, .41 sg.
Adirondack Red Spruce (Picea Rubens) – this is the prized top wood used on many of the great pre-war, now antique collectible guitars. Produces a strong, clear tone. Fine quality Red Spruce is difficult to find, and very expensive. 28 lb/ft, .43 sg.
Cedar – Cedar has been used for many years in the classical nylon guitar industry, and lately for steel string guitars also. Our Cedar is the Western Red Cedar (Thuja Plicata). Coloring is creamy tan to light brown. Produces a somewhat more mellow “broken in” tone than most spruces. 23 lb/ft, 32 sg.
Port Orford Cedar or White Cedar (Chamaecyparis Lawsoniana) – although known as “cedar” this wood is not a true Cedar, but instead in the Cypress family. A very rare and expensive soundboard wood, producing a bold and strong responsive tone. Golden white with tight, even grain. 30 lb/ft, .48 sg
Sequoia Redwood – This is the tall, west coast US Redwood tree that has been used for many years for stringed instruments. The color is somewhat red, but very pale red, and combines well visually with most back and side woods. Redwood flexibility is similar to Cedar but leans more toward Spruce characteristics, combining the best of both. Since no new cut Redwood is available (i.e. you can not cut down Redwood trees), we use environmentally salvaged 80 to 100 year old lumber remnants (torn down houses and barns). 26 lb/ft, .42 sg.
For more information and ordering:
Ko’olau Guitar & ‘Ukulele
401 N. Cane Street, A-10
Wahiawa, Hawaii 96786
(808) 622-1064 • Fax: (808) 622-1646