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Blunting Effect
Boring
Carving
Comments
Common Names
Common Uses
Countries of Distribution
Cutting Resistance
Distribution Overview
Drying Defects
Ease of Drying
Environmental Profile
Family Name
Gluing
Grain
Heartwood Color
Kiln Schedules
Luster
Mortising
Moulding
Movement in Service
Nailing
Natural Durability
Numerical Data
Odor
Planing
Polishing
Product Sources
References
Regions of Distribution
Resistance to Impregnation
Response to Hand Tools
Routing & Recessing
Sapwood Color
Scientific Name
Screwing
Staining
Strength Properties
Texture
Trade Name
Tree Size
Turning
Varnishing
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Common Names
Koa
Regions of Distribution
Oceania and S.E. Asia
Countries of Distribution
[VIEW MAP]
Hawaii [US]
Common Uses
Bent Parts, Boat building, Building materials, Canoes, Core Stock, Decorative veneer, Drum sticks, Excelsior, Figured veneer, Gunstocks, Interior construction, Joinery, Lifeboats, Musical instruments , Novelties, Organ pipes, Paneling , Piano keys, Pianos , Plain veneer, Rifle stock, Shipbuilding, Sounding boards, Sporting Goods, Veneer, Violin bows, Violin, Wainscotting, Xylophones
Environmental Profile
| Rare |
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| Status has not been officially assessed |
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| Appears to be rare in much of its natural habitat |
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Distribution Overview
Found exclusively on the Hawaiian Islands, Koa trees reach a height of 100 feet with a diameter of 4 feet. It grows at most elevations on the islands, but grows best in areas of heavy rainfall form 3,000 to 6,000 feet. It is the most conspicuous tree growing between the low, open dry forest and the wet ohia forest, and is generally quite adaptable to a variety of climates.
Heartwood Color
| Brown |
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| Red |
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| Yellow |
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| Purple |
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| White |
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| Highly variable |
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| Tan |
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| Reddish brown |
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| Pale blond |
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| Golden brown with a reddish cast |
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| Color varies considerably |
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| Chocolate |
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The wood yellows quickly in sunlight, which adversely affects its exterior performance
Sapwood Color
| Brown |
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| Red |
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| Pale brown |
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| Clearly differentiated from the heartwood |
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Grain
| Figure |
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| Wavy |
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| Closed |
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| Interlocked |
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| Fiddleback (figure) |
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| Other (figure) |
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| Growth rings (figure) |
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| With distinct light and dark bands |
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| Wavy |
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| Moderately to severely interlocked |
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| Figure shows a rainbow pattern |
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| Fiddleback figure |
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| Curly |
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Attractive patterns
Texture
| Coarse |
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| Medium |
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| Medium coarse to coarse |
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Luster
Natural Durability
| Perishable |
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| Non-resistant to termites |
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| Non-durable |
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| Very little natural resistance |
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| Highly susceptible to attack by subterr. and dry wood termites |
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Odor
| No specific smell or taste |
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Kiln Schedules
| Schedule F (4/4) United Kingdom |
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| 6 - D4 (4/4); T3 - D3 (8/4) US |
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Drying Defects
Problems generally only with thicker stock
Ease of Drying
| Reconditioning Treatement |
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| Fairly Easy |
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| Little degrade |
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| Little or no degrade |
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| Easy |
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Tree Size
| Tree height is 20-30 m |
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| Trunk diameter is 100-150 cm |
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The trees are very hardy and can survive under almost any environmental condition
Product Sources
Supplies of Koa are available on the U.S. market in the form of lumber and veneers. Prices are in the high range.
Comments
Excellent for musical instruments because of its high resonant properties. Hawaiian ukeleles are made exclusively from koa wood. Trees that grow at high exposed areas produce the best figured wood, and the veneer form of Koa is highly valued for fine furniture because of its fiddleback figure and high finish it takes. Koa wood is similar to Black walnut (Juglans nigra)
Blunting Effect
Boring
| Fair to good results |
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| Fairly easy to very easy |
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Carving
| Fair to Good Results |
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| Fairly Easy to Very Easy |
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Cutting Resistance
| Fairly Difficult to Very Difficult to saw |
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| Difficult to saw |
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Interlocked grain. Keep tools sharp to prevent tearouts
Gluing
| Poor to Very Poor Results |
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Gluing properties are variable, but they are generally poor
Mortising
| Fair to Good Results |
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| Fairly Easy to Very Easy |
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Moulding
| Fair to Good Results |
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| Fairly Easy to Very Easy |
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Movement in Service
| Excellent Stability - Small Movement |
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| Fair to Good Stability - Medium Movement |
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| Stable |
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Nailing
| Fair to Good Results |
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| Fairly Easy to Very Easy |
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| Satisfactory nailing properties |
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Planing
| Fairly Easy to Very Easy |
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| Fair to Good Results |
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| End-grain material requires very sharp cutting edges |
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| Easy to plane |
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Wood containing curly grain may require a cutting angle of 20 degrees for best results
Resistance to Impregnation
| Resistant sapwood |
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| Resistant heartwood |
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Very resistant
Response to Hand Tools
Routing & Recessing
| Fair to Good Results |
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| Fairly Easy to Very Easy |
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Screwing
| Fair to Good Results |
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| Fairly Easy to Very Easy |
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Good screw holding properties
Turning
| Fair to Good Results |
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| Fairly Easy to Very Easy |
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Polishing
| Fair to Good Results |
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| Fairly Easy to Very Easy |
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| Very Good to Excellent Results |
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| Excellent results |
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Staining
| Fairly Easy to Very Easy |
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| Fair to Good Results |
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| Very Good to Excellent Results |
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| Stains very well |
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Varnishing
| Fairly Easy to Very Easy |
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| Fair to Good Results |
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| Very Good to Excellent Results |
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| Very well |
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Strength Properties
| Weight = high |
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| Density = high |
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| Compression strength (parallel to grain) = high |
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| Bending strength (MOR) = high |
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Numerical Data
| Item | Green | Dry | English |
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| Bending Strength | 7389 | 11226 | psi |
| Density | | 37 | lbs/ft3 |
| Maximum Crushing Strength | 3695 | 6537 | psi |
| Shearing Strength | | 1662 | psi |
| Stiffness | 1293 | 1520 | 1000 psi |
| Specific Gravity | | 0.54 | |
| Weight | 39 | 32. | lbs/ft3 |
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| Item | Green | Dry | Metric |
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| Bending Strength | 519 | 789 | kg/cm2 |
| Density | | 592 | kg/m3 |
| Maximum Crushing Strength | 259 | 459 | kg/cm2 |
| Shearing Strength | | 116 | kg/cm2 |
| Stiffness | 90 | 106 | 1000 kg/cm2 |
| Specific Gravity | | 0.54 | |
References
Boone, R.S., C.J. Kozlik, P.J. Bois and E.M. Wengert. 1988. Dry Kiln Schedules for Commercial Woods: Temperate and Tropical. USDA, Forest Service, Forest Products Laboratory, General Technical Report FPL-GTR-57, Madison, Wisconsin.
Constantine, Jr. A.J. 1975. Know your Woods: A Complete Guide to Trees, Woods, and Veneers. Revised Edition. Revised by Harry J. Hobbs. Charles Scribner and Sons, New York.
Imported Wood Purchasing Guide: A Comprehensive Purchasing Reference for Imported Woods. 1992. 20th Edition. International Wood Trade Publication, Inc. 1235 Sycamore View, Box 34908, Memphis Tennessee.
Kaiser, J. 1990. Wood of the Month: Koa - The Wood from the Hawaiian Islands. Wood & Wood Products, January 1990, Page 48.
Keating, W.G., Bolza, E.,1982,Characteristics properties and uses of timbers. South East Asia, Northern,Australia and the Pacific,C.S.I.R.O. Div. Chemical Technology,Inkata Press,1
Kline, M. 1982. Acacia koa - Koa. In A Guide to Useful Woods of the World. Flynn Jr., J.H., Editor. King Philip Publishing Co., Portland, Maine. 1994. Page 12.
Lincoln, W.A. 1986. World Woods in Color. Linden Publishing Co. Inc., Fresno, California.
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