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Curly Redwood Fracture?
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Author:  Kevin Mason [ Sun Oct 06, 2013 4:54 pm ]
Post subject:  Curly Redwood Fracture?
Has anyone encountered this kind of fracture before, and is there any way to hide them. This is my first curly redwood top and I've read about its propensity to split, but this cross-grain fracturing seems strange. The top is braced and attached to the sides and I didn't notice these fractures until I started sanding the top before I shellacked it and started binding the instrument (a tenor uke). At first I thought they were sanding scratches, but when I on my magnifiers, I realized they were fractures. Since I was afraid of them spreading, I applied some medium viscosity CA glue. Unfortunately, the CA glue really soaked in and darkened the wood and also made the fracture more visible. I sanded more, but it didn't help. So I went ahead and painted shellac hoping it would at least darken the wood to match the CA stain. As I think you can see, it didn't work. Before I start over, I was hoping someone out there might have a magic cure.

Image
Author:  wbergman [ Sun Oct 06, 2013 5:15 pm ]
Post subject:  Re: Curly Redwood Fracture?
I used CA on a crack on a built redwood guitar and the area with the CA turn very dark--almost black.
Author:  meddlingfool [ Sun Oct 06, 2013 7:15 pm ]
Post subject:  Re: Curly Redwood Fracture?
It looks like compression fracture like you sometimes see in mahogany. I don't think there's a fix, sorry.
Lets hope I be wrong....
Author:  DannyV [ Sun Oct 06, 2013 7:22 pm ]
Post subject:  Re: Curly Redwood Fracture?
I've seen a few cracks like that. Not in Redwood since I don't see a lot of it. It can happen when the tree is felled. Hits the ground, boom. I think about the only fix is to do an inly over top. Otherwise, looks like a do over. Sorry you're so far along. That kinda sucks but I guess at least you didn't have the bindings done.
Author:  runamuck [ Sun Oct 06, 2013 8:20 pm ]
Post subject:  Re: Curly Redwood Fracture?
Yeah, I agree with the others: a compression fracture.

I've never found any cross grain crack, joint, or otherwise, to disappear - not matter what, unless, of course the finish is opaque.

And I think that an inlay (not that you'd want to do that on a guitar top anyway) is impossible because you'll never match up with the curl.


That's heartbreaking.
Author:  DennisK [ Sun Oct 06, 2013 9:17 pm ]
Post subject:  Re: Curly Redwood Fracture?
I think you've just joined the club of people who don't build with curly redwood.

Sadly, I don't think there's any fixing it when that happens. Possibly hide glue plus pressure on both sides of the plate (good opportunity to put those neodymium magnets to use :)) to swell the grain and glue it back together, but it probably would have still been visible.

I'm almost sure those are actually radial cracks, but it's just that the curl is so intense, you're looking at about 45 degrees off of endgrain there, so they show up as "cross grain".

Not all figured redwood is crickly crackly like that though. I have some light curl sets that feel nice and strong... too many of them, actually, so I'll be putting a couple up for sale in the classifieds here in the next day or two, along with a bunch of other stuff. I also have a really intense tight curl set that makes crackly noises if I even lightly flex it. Pretty sure that one will be needing a CA bath before I use it. Or laminated.

What did that top feel like when working with it? Do you have any offcuts that you could flex along the grain and see how easily they split in the curls?
Author:  James Ringelspaugh [ Mon Oct 07, 2013 12:29 pm ]
Post subject:  Re: Curly Redwood Fracture?
Yep, compression failure. Nothing you can do to hide it short of splicing in a wide piece... and given the figure plus the fact that the grain isn't straight that would surely show. Long grain stiffness and strength is compromised as well; each of those fractures is pretty much an end grain butt joint with equivalent strength. Painful as it may be, I would toss it and start over.
Author:  Kevin Mason [ Mon Oct 07, 2013 12:48 pm ]
Post subject:  Re: Curly Redwood Fracture?
Thanks everyone. I won't waste any more effort on this top. Now I need to decide whether to try again or join the "I'll never again use curly redwood club."
Author:  Clay S. [ Wed Oct 09, 2013 9:29 am ]
Post subject:  Re: Curly Redwood Fracture?
You could mask off the rosette and do a black lacquer top.
Author:  mcgr40 [ Thu Oct 10, 2013 10:15 am ]
Post subject:  Re: Curly Redwood Fracture?
I have seen that in a lot of very high figure woods- I really think it is caused by that spot being having such a high percentage of end grain- so it dries much faster and it is just like a microcheck in the end grain of a plank. I suspect the crack was always present in the set, just too difficult to see. I do wonder if the somehow the pieces became flipped, since one piece shows the check and the other does not. Is it possible the cracked piece was the very outside of the plank, and the resawn face is inside the body? I tend to think the fracture would show on both pieces- or else- I would think it more pronounced on the inside of the plate that is now cracked.
Sorry I know of no fix. But I do tend to beleive HHG is generally less visible.
Author:  jfmckenna [ Fri Oct 11, 2013 7:13 am ]
Post subject:  Re: Curly Redwood Fracture?
mcgr40 wrote:
I have seen that in a lot of very high figure woods- I really think it is caused by that spot being having such a high percentage of end grain- so it dries much faster and it is just like a microcheck in the end grain of a plank. I suspect the crack was always present in the set, just too difficult to see. I do wonder if the somehow the pieces became flipped, since one piece shows the check and the other does not. Is it possible the cracked piece was the very outside of the plank, and the resawn face is inside the body? I tend to think the fracture would show on both pieces- or else- I would think it more pronounced on the inside of the plate that is now cracked.
Sorry I know of no fix. But I do tend to beleive HHG is generally less visible.

Yeah I think so too. I built one guitar with a curly Redwood top and it's been out in the wild now for ten years so far so good. But I went to build another guitar from the same plank I cut the top from on the first one and I saw these very same cracks the OP posted. Chalk me up as one of the 'never will use curly top wood again' crowd. Unless it's used for a double top. It's too bad too because that top is so nice looking.
Author:  SteveT [ Fri Oct 11, 2013 6:08 pm ]
Post subject:  Re: Curly Redwood Fracture?
Before you start over, flood the top with CA & scape back. If the color becomes relatively uniform, you might have saved the top. Weight added likely to be less than 20 g.
Author:  Clay S. [ Fri Oct 11, 2013 7:46 pm ]
Post subject:  Re: Curly Redwood Fracture?
Paint a hula girl scene over it. What's old is new.
Author:  Kevin Mason [ Sat Oct 12, 2013 6:26 pm ]
Post subject:  Re: Curly Redwood Fracture?
After mulling all of this over, and discussing it with the client, I took the top off the body and will be replacing it with a Lutz spruce top. It was painful removing because it was such a beautiful piece of wood. At least I was able to salvage the rosette.
Author:  jfmckenna [ Sat Oct 12, 2013 7:39 pm ]
Post subject:  Re: Curly Redwood Fracture?
kmason wrote:
After mulling all of this over, and discussing it with the client, I took the top off the body and will be replacing it with a Lutz spruce top. It was painful removing because it was such a beautiful piece of wood. At least I was able to salvage the rosette.


Yeah that did look beautiful. Keep it for future rosette's or something like that. That rosette was really nice looking too so it's good you managed to salvage that!
Author:  Alan Carruth [ Mon Oct 14, 2013 8:27 am ]
Post subject:  Re: Curly Redwood Fracture?
That does look like a compression fracture to me, too.

It's well known that it's possible for a large tree to build up sufficient compression stress near the core low down in the trunk that it can actually exceed the strength of the wood. When that happens you can get microfracturing; the cell walls get crushed. Wood like that will 'brash fracture' in bending: break off more or less cleanly across the grain. This is similar to the 'wind checking'' that you sometimes see, particularly in mahogany, when the tree is improperly felled onto something, such as another tree or a rock, which causes local compression fractures. The difference here is that you normally can see wind checks, while compression fractures from load may be invisible. Also, I'd think that 'wind checks' would be more common toward the outside of the tree, whereas this sort of compression fracture is in toward the center, due to the normal sort of built-in stress levels.

I've often wondered about the figure in curly redwood. It doesn't really look like the sort of curl that you see in maple, nor is it particularly like some of the other things, like blister or quilt figure. To me it's always looked more like the wood was squashed down after it grew. I've worked some redwood that had the beginnings of that sort of figure, and it's never been very good: it seems to me that I've always had trouble wiht stability and cracking with it. Anyway, as sexy as the curly redwood has looked, I've avoided it in the past for that reason. Seeing your photo, I'm going to continue to do so.
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