Koa prone to cracking?

JonThysell

JonThysell

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Took in a solid acacia uke to get a crack beneath the bridge fixed, guy said it wasn't my fault, all Koa ukes crack eventually regardless of humidity, even in Hawaii.

AFAIK he was talking out his a**, and it was my own fault for letting the humidity drop to 16% in my apartment. I can understand that as a repair shop he's probably biased toward seeing lots of cracked ukes from people who don't even monitor humidity, but still. All Koa ukes?

Or am I totally wrong here?
 
Well, I've only owned Koa ukes for 4 years, so that isn't very long. However, I haven't had one crack. I have seen vintage Koa ukes from the 20s that haven't cracked; so I think if you keep your humidity correct and handle them with TLC, they should be fine.
 
I hope not! (and I don't believe so)
 
Wood is a dynamic medium that responds to its environment and koa is no different.
But to say it always cracks is absurd.
 
Any solid wood can crack if it is too dry for too long. Some woods crack faster than others. I don't believe that Koa will always crack no matter what, but it can crack in very dry climates.
 
what about warp?
 
That is a bit much to say all koa ukes crack. But at 16% that is far below what I would want my ukes to be at. When I see the humidity dropping to 40% I always have a Oasis nearby to put in the case which usually bumps it up to 50% to 55%.
 
A few weeks ago when the humidity here in Los Angeles went down to 5%, my Lanikai monkey pod (similar to koa) cracked before I could seal up the shelf I built for my ukes. Ended up gifting it and getting a zebra wood in replacement and made sure my shelf was sealed, which now stays at a steady 52%. So far my acacia koa is doing fine. (I never know if there is or is not a space in monkey pod/monkeypod, zebra wood/zebrawood, acacia koa/acaciakoa.)

Monkeypod crack.jpg
 
A few years ago, a great many S.E. Asian acacia ukes cracked due to improperly dried wood. My Koa Mele is about 8 years old...no cracks, no hydrometer.
solid Acacia KPK and Lehua no problems either. Koa Kamaka white label from early 70's..nope, no problems either.
 
I don't think Koa is more prone to cracking than other hard woods - all hardwoods might be a bit more prone to cracking than softer tonewoods like pine and cedar (though I'm not sure about that).

There are many, many old mahogany ukes that are cracked.

John
 
Yeah, I doubt they were using much in the way of humidity control in the old Hawaiian uke building shops.
If a builder dries his wood, before & while building, to a moisture content below what it will experience out in the world, it won't crack unless it is sat upon.
Imagine an open air shop building ukes in Vietnam, the lowest the RH would ever be is 80-90%. It could crack if you kept it humidified at 70%
Even Koa, which is a pretty stable and crack resistant wood, will crack if it is left to dry to a lower MC than when it was built.
 
David Newton said:
Yeah, I doubt they were using much in the way of humidity control in the old Hawaiian uke building shops.
If a builder dries his wood, before & while building, to a moisture content below what it will experience out in the world, it won't crack unless it is sat upon.
Imagine an open air shop building ukes in Vietnam, the lowest the RH would ever be is 80-90%. It could crack if you kept it humidified at 70%
Even Koa, which is a pretty stable and crack resistant wood, will crack if it is left to dry to a lower MC than when it was built.
Click to expand...

That's good to know. This uke that cracked is a Thai-made Melokia, and the drop to 15% (from 45-55%) was pretty sudden, which I totally take responsibility for not tucking away my ukes sooner.
 
JonThysell said:
That's good to know. This uke that cracked is a Thai-made Melokia, and the drop to 15% (from 45-55%) was pretty sudden, which I totally take responsibility for not tucking away my ukes sooner.
Click to expand...

A sudden change in humidity is not so much of an issue as duration. Even with a severe drop in humidity it simply takes moisture some time to migrate into or out of wood. I see a lot of people who fear taking their uke out of the case on a dry dessert day to play, for example. That shouldn't be a problem, as long as you put it back in a case with a humidifier when done playing, etc. What you have to do is watch the average humidity around the uke.

You can also over-humidify, though the damage of such is usually less severe than under-humidifying and a too-wet uke will often "repair itself" if brought back to normal humidity.

Sudden changes in temperature, however, can be a whole-nuther story - some finishes, and it's sometimes the best, most expensive finishes - can be quite sensitive to rapid changes in temperature.

John
 
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