Koa Virgin

eclipsme

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I just purchased some lovely Koa. This is my first experience with it. Turns out, Koa is much lighter than I thought!

As I begin contemplating my first build with an unfamiliar wood, I wonder if anybody has any tips, warnings, cautions.

Koa also seems softer than I thought, so I can see its utility as a soundboard, but what about back and sides, where stiffness seems more desirable. And yet I have played an all solid Koa uke and it was quite nice.

Thank you for any pointers!
 
I've found koa (Acacia koa) to be easy to work with. Bends politely, sands well, takes a finish nicely and glues well. My only negative observation is that it can "chip" along the grain line if you are not careful.
 
Koa is a wood that defies generalization. It can be light or heavy, stiff or floppy, soft or extremely dense. As far as appearance goes, some of the fancier kind might be better off as jewelry boxes while while the more boring koa may make excellent instruments. And the reverse is also true! Knowing how to work with each of these characteristics is always a challenge for the builder. When working with koa it’s important to know what you’re doing and not simply “build by the numbers”. Experience is your best teacher. Good luck.
 
Aloha and mahalo Chuck, we are just fine here and hope you are doing well
also.
Brad
 
One other negative I forgot to mention, and it is an important one, is that koa can be quite open pored and will wick thin CA glue along the grain line discoloring it and leaving unsightly black lines. Easy to prevent however: Seal end grain with dilute shellac before using thin CA glue and you will not get wicking. Otherwise, always a delightful wood to work with.
 
One other negative I forgot to mention, and it is an important one, is that koa can be quite open pored and will wick thin CA glue along the grain line discoloring it and leaving unsightly black lines. Easy to prevent however: Seal end grain with dilute shellac before using thin CA glue and you will not get wicking. Otherwise, always a delightful wood to work with.

Maybe it’s just me but I’ve never had that problem. Spruce or cedar? Sure. But never with koa. Maybe it was unique to that particular set of koa. I also pore filled with CA.
 
Yeah, it was from a set from reclaimed old growth koa and was dry and hard as a bone. What also happened was after the rosettes had been glued in with thin CA, the glue went all the way through the top and appeared on the down side as black spots out lining the rosette. Looked awful but NO matter! Nobody knows it is there except me! Ha!... In my experience the worst wood for this phenomenon is redwood. Definitely seal redwood around thin CA.
 
Yeah, it was from a set from reclaimed old growth koa and was dry and hard as a bone. What also happened was after the rosettes had been glued in with thin CA, the glue went all the way through the top and appeared on the down side as black spots out lining the rosette. Looked awful but NO matter! Nobody knows it is there except me! Ha!... In my experience the worst wood for this phenomenon is redwood. Definitely seal redwood around thin CA.

Sounds like you got some rotted, or at best spalted, koa.
 
Thank you all for the comments. I will continue watching this thread for any others.
 
From my experience (being a total of one koa uke), stay away from water-based pore fillers. I used some over shellac, sanded between coats and on the second application, it made ugly, olive drab blotches wherever the sanding had exposed bare koa.
 
From my limited experience (half a dozen koa ukes, so 18 different boards involved), some koa is very porous, some not. A simply test is to splash naphtha on - if it appears on the other side immediately, be careful about glue and finish soaking through and seal carefully.

For me, koa usually planes and scrapes easily to a good finish.

It also bends really easily unless it is highly figured. On my latest build I had 3 sets of sides, all from the same board, which were prettily figured. I broke 5 of the 6 boards, and saved the last for something different. Because of the figuring, in places the grain direction was at nearly 45 degrees to the long dimension, so there was no way they were going to bend without cracking. If you have the choice, plain koa for sides!
 
From my experience (being a total of one koa uke), stay away from water-based pore fillers. I used some over shellac, sanded between coats and on the second application, it made ugly, olive drab blotches wherever the sanding had exposed bare koa.

Thanks for the heads up!
 
From my limited experience (half a dozen koa ukes, so 18 different boards involved), some koa is very porous, some not. A simply test is to splash naphtha on - if it appears on the other side immediately, be careful about glue and finish soaking through and seal carefully.

For me, koa usually planes and scrapes easily to a good finish.

It also bends really easily unless it is highly figured. On my latest build I had 3 sets of sides, all from the same board, which were prettily figured. I broke 5 of the 6 boards, and saved the last for something different. Because of the figuring, in places the grain direction was at nearly 45 degrees to the long dimension, so there was no way they were going to bend without cracking. If you have the choice, plain koa for sides!

I shall remember this! (I hope!)
 
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