Martin & MacArthur

Q: Is koa an “endangered” wood? Will we run out of koa in the next 50 years?
A: No. Koa is the second most common tree in Hawaii. There are presently over 20,000 acres being grown commercially. (The present industry in Hawaii would need to grow less than 6,000 acres on a sustainable basis.) It will be in restricted supply for 15-20 years until some of the new plantations are ready for harvest.

Q: What makes the color variations of koa? (Does lighter koa mean a younger tree & darker koa an older tree?)
A: Mostly it is to do with the soil type where the koa is grown, but older koa is generally darker. Dark koa furniture will darken with age, light koa will lighten with age.

Q: What makes koa curly? What percent of a typical koa tree is curly? Where on a tree is the curly wood found?
A: It is unknown what makes a tree curly other than "crotch" curl (sometimes called fire curl). It usually occurs in stressed locations such as a fork of a tree. Rarely is a tree 100% curly; it is usually localized. Less than 3% of trees have curl.

Q: How old should a koa tree be before cutting it? How big is a koa tree when it is cut?
A: Trees are sometimes cut as young as 20 years. We mostly use dead and dying trees that are probably 50-80 years old. (Hardwood trees do not have growth rings so it is hard to tell.) Trees will grow as old as 200 years but in some areas where there are not much topsoil, they may die after 60 years. Trees are usually between 15" to 60" in diameter.

Q: Is koa grown anywhere else in the world?
A: Acacia koa grows ONLY in Hawaii, it does not grow anywhere else. Koa from the different Hawaiian Islands looks different. The closest relative is acacia melanoxin “black wattle” from Australia, but this is clearly different from koa. There have been some less than ethical importers from the Philippines who have tried to pass off a Philippine wood (nara) for koa.

Q: Is koa “the” most prized wood for Hawaiians?
A: It depends on the usage. There are harder woods for digging sticks etc., but koa certainly is the most versatile for building canoes, houses and so on.

Q: Is the mango wood that we use “common” mango?
A: Yes, but we only use figured mango which does not occur in all trees.

Q: Do you use Hawaiian ash or mainland ash?
A: Usually mainland ash; Hawaiian ash is not available consistently.

Q: What kind of forestry management program is the koa wood under?
A: On State land there is no management for koa production. Private lands vary from extensive replanting of seedling trees, scarification or just taking the cattle off the land. Koa itself grows very easily, but is a highly desired food for cattle, goats and sheep, all of which are a problem on the Big Island. Animal control and control of competing alien weeds is the main management action needed to grow koa.

Q: Since koa is a hardwood, what is its relative hardness compared to teak, oak, walnut etc.?
A: About the same as walnut. Harder than teak, softer than oak, but varies a lot, sometimes harder than maple, sometimes softer than mahogany.

Q: Is there anything that can keep termites away from the wood used for furniture? Do termites like koa?
A: Chemical pre-treatment will work, but may discolor the wood. Termites do not prefer koa but will eat it if desperate.

Q: How long does it take to air dry koa naturally before it can be used to make furniture?
A: 1" thick-60 days; 2" thick-90 days; bedposts-over one year; varies with average humidity.

Q: How long does it take to kiln dry koa?
A: 1" thick-30 days; 2" thick-45 days; bedposts-over 6 months.

Q: How much does koa cost by the board foot?
A: Martin & MacArthur lumber department sells it at $8.00 to $30.00, depending on the grade.

Q: How do we prolong the life of koa? Can the sun damage it?
A: Extend the life of koa by regular treatment with products such as “Milsek” furniture oil, keep out of direct sun light. Direct sun light will bleach the color out of koa and it cannot be restored.

Q: How do we refinish koa?
A:
Option 1.) Strip off the existing finish down to bare wood (which is difficult if “Pledge” or other waxy polishes have been used). Then, resand in detail, steam out dings and finish as a new piece.
Option 2.) Especially with historic furniture, we sometimes only cleanup the piece, repair damaged parts and apply furniture wax. However, the piece will still look old.

Q: Are there different kinds of koa wood?
A: Botanically, no. In terms of color, grain, figure etc., there are no two trees the same; there is a major variation with location.

Q: What makes koa a special wood?
A: Variability, richness, luminescence, unique to Hawaii, most beautiful wood in the world.

Q: How can you tell the quality of koa wood furniture?
A:
a.) all pieces of wood in a furniture item match in color and grain.
b.) accurately made, strong joints.
c.) crisp details e.g. sharp edges.
d.) consistent unobtrusive finish.
e.) quality accessories, drawer slides, hardware etc.
f.) design and detailing that is ascetically pleasing.

Q: Where is our koa purchased?
A: Nearly all is purchased from the Big Island of Hawaii, mostly from cutters who contract with ranchers