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I bought some very nice cocobolo about 6 months back and made a dozen fretboards from it. This wood was almost perfectly quartersawn. The original boards were 4/4 x 6" and roughly 36" long. The boards sat in my shop for all this time at 40% RH and the temp didn't vary by 15 degrees...save one night when the power went out.

I cut them into fretboard blanks about a month ago and let them sit a few days before they were made into fretboards. They were all straight a few days after being finished but now, after a few weeks, I notice a few of them have "crooked". Mostly they are perfectly straight but this is still a disappointing surprise.

So far, I've only read Hoade's short mention of this in, "Understanding Wood" in which he owes crooking to "juvenile" or "reaction" wood. This doesn't help explain what happened very much.

1. Will reaction wood EVER settle down? ...which may make a case for storing it longer. If so, how long should one store wood to make it a safe bet.

2. Is the only difference between juvenile wood and reaction wood the fact that juvenile wood MIGHT settle down and reaction wood won't?

3. Is cocobolo generally considered stable? Best I can find is that it's supposed to be pretty stable but of the four fretboards that went south, three of them went wildly south...trying to get home maybe?

Thanks in advance.

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I read Emerson on the can. A foolish consistency is the hobgoblin of little minds...true...but a consistent reading of Emerson has its uses nevertheless.

StuMusic

Like Peter Pan, juvenile wood never grows up. Reaction wood never gets stable.

But was your board straight grained? What did the end grain look like? Juvenile wood is from the center of the tree. You can tell by the curvature of the rings. Reaction wood is usually branch wood, or wood from a non-vertical trunk (can also be from wind stress). Straight grained wood is not very likely to be reaction wood.

A more simple explanation might be that the wood had a bunch of runout, from twist in the tree or how it was milled.

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Howard Klepper
http://www.klepperguitars.com

When all else fails, clean the shop.

How long was the wood down and how was it dried and stored prior to your acquisition? Did you check it with a moisture meter when you got it? While 6 months is plenty of time for properly dry wood to acclimate to shop conditions if the wood was not completely dry, a few years of air dry may be necessary for a 4/4 board to dry and stabilize completely through. Even kiln drying may not completely dry out a board, at least evenly. What most likely happened IMHO is that the moisture content was not even throughout the lumber just yet. Exposing the wetter interior to the air caused it to dry fairly rapidly ( a few weeks) in that section and caused the lumber to warp and or twist. I would guess that those cut from the center most portion of the boards are the worst offenders. Of course this brings back something one of my mentors told me many years ago " Wood is like a woman, you never really know what it's gonna do or when it's gonna do it".
Of course I mean no offense to our members of the fairer sex.

Brian

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Brian

You never know what you are capable of until you actually try.

https://www.howardguitarsdelaware.com/

4/4 lumber takes at least a year to season, some denser woods alot longer. This is the very reason i don't resaw any wood before it is properly seasoned. I don't like ending up with potato chips and that's what you usually get when resawing green wood. There's others here that will disagree, but to each his own.

Not sure from your description if they have been fretted, or if they are still just blanks. If just blanks, I have done this before. I had a couple of steel plates which I heated, clamped the boards between them, and put them in an oven for a few hours (forgot the temperature, but above 250F), then let them cool over night in the clamps. After unclamping, they stayed totally flat laying around for many months. Expect your clamps to rust.

I think you could do the same thing by setting up similar to a bending operation with slats and a heating blanket, but just lay the sandwich down on a flat surface and weight it down a little. Let it sit over night.

Maybe this would work, maybe not, but the alterntive is to toss the wood.

I have a number of heating plattens and blankets. It's likey I can rig something up to bend these back. Though I have eight goods ones out of this batch I'm going to try this just to see how it goes.

Good to learn some coping techniques.... thanks guys.

The figure and grain was straight as an arrow. Two of ones that crooked had a tiny bit of runout...hard to say twisted grain was a the cause of this. Maybe...but I'd put the runout at about 10 degrees or less.

The wood was stored in an uncontrolled warehouse at a local lumberyard. Who knows for how long...they were just beautiful so I grabbed them. I figured six months in my shop was enough but I'm happy enough to think that perhaps only more patience might have improved these results. I hope that's the case. I hate trying to move forward without truly understanding what just happened behind me.

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I read Emerson on the can. A foolish consistency is the hobgoblin of little minds...true...but a consistent reading of Emerson has its uses nevertheless.

StuMusic

How have the resawn fingerboards been stored? If they were laid flat with only one side exposed to the air, that can explain the warpage.
The other explanation is casehardening, where the outside of the board is under tension or compression, due to uneven drying. Moving the wood from uncontrolled storage to your humidity-controlled shop can cause uneven moisture distribution, and six months is generally not long enough for 4/4 cocobolo (or most hardwoods) to equalize.
Since the wood is straight-grained and QS, I doubt that compression wood or juvenile wood are involved.
If it is simply uneven moisture and not casehardening, I would just sticker the fingerboards for a few months under humidity control and wait. I'll bet that the warped ones will straighten on their own.

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John