osage delaminate

[Renacs]

 I dont think delaminate is a word, but you probably understand. Anyway I've started on my trade bow and I was kicking butt. Then I notice some cracks running with the grain throughout the stave. I've worked through most of them "which left the stave as a bend through the handle bow". But I'm Concerned that there might be some hidden stresses inside.
  My question is what do you think would cause these? Maybe moisture and temperature change? I have also split another and noticed the same thing. These are from two different trees harvest three to four years ago. And one has been split since then...
  I'm trying to post a pic but my phone is stupid.

[Renacs]

Oh yea, it's osage

[Hrothgar]

One possibility is fire caused. I cut and dried some osage that had been in a 'forest fire' several years ago. It too had cracks running top to bottom with the grain, but it made an ok bow. Parts of the tree looked like it had gotten hot enough to explode/crack open.

[Josh B]

Delamination is what it is usually called.  Also known as wind checks.  Its pretty common in Osage from hedgerows that take the full brunt of wind storms.  If it's in the nonbending handle area, you can warm the wood up and saturate the crack with thin superglue.  The crack will still show, but it won't hurt anything.  If the delamination is in the working part of the limb, that's a problem.  I've never had one hold together if it was in the working limb.  I've heard others say they've pulled it off, but I certainly have not.  Here's my daughter's new bow showing a few wind checks through the arrow pass that I doped with superglue.  Kind of an eyesore but structurally sound.  Josh

[Renacs]

 It's not fire, since it came from my woods, I've found several pieces like that in my stash. My theory is extreme cold, since last year was pretty extreme here in Ohio. But I don't know if that really makes sense.

[SLIMBOB]

Pictures would help a lot.  If they are wind shakes (delam along the hardwood rings) that's one thing.  If they are simply drying checks (on the back or belly) nuther thing entirely.

[Eric Garza]

It would be useful to differentiate between delaminations and checks. When I use the term delamination, I refer to a crack that spreads through usually the early wood of a growth ring, essentially separating one growth ring from the one below or above it. When I use the term check, or wind check as some call them, I'm referring to a crack that opens on a bow's back or belly that doesn't necessarily follow a ring.

It's been my experience that wood that is very dense (like osage) can hold onto moisture for surprisingly long periods of time. When you split a log or large stave that's been sitting around, or if you move a split stave that's been in a humid environment for a long time into a very dry environment, then the rush of moisture leaving the wood exposed to the air causes it to contract and split around deeper wood that's still holding onto its moisture and maintaining constant volume. If the split happens to follow through the early wood of a growth ring, you get delamination. Otherwise you get a check.

If I can't get rid of delaminations in the bending portions of limbs by removing wood, I usually put the stave in the burn pile. I invest way too much time in my bows to risk having one explode because of something like this.

[Renacs]

 It is wind checks. And it's going in the burn pile. I never want one of my bows to hurt anyone. But it's strange that two different staves from two different trees had the same problem. But I guess if you work with enough wood you'll see strange things.

[Josh B]

I stand corrected.  Slim and Eric are correct, the proper term is wind shakes.  It's not uncommon for a lot of the trees in the same area to have wind shakes.  They are usually caused by strong winds twisting the trees, so the same storm probably damaged both trees.  As disappointing as it is, it's probably best to discard them or preferably use them for another purpose.  Josh

[Eric Garza]

Actually, I think Gun Doc is referring to something else besides what I was talking about. I've seen larger logs with cracks deep in the heartwood caused by flexing of the tree due to wind or other sources of physical stress or strain. Sometimes these cracks can reach near-enough to the outside of a log that they'll show up on the bellies of staves, and the bellies of bow limbs. If this is what GD is talking about, then I don't think I'd call that a check or a delamination, I'd call that a stress crack. But since they can be caused by wind, maybe wind check would work too?

I've always used the terms 'wind check' and 'check' interchangeably to refer to cracks caused by differential drying of a piece of wood. I suppose the word 'check' could be reserved for cracks caused by differential drying, and 'wind check' reserved for stress cracks caused by the force that wind exerts on a standing log.

Terminology...

[Josh B]

You mean like these?   What I was referring to is laminar separations between the growth rings.  What I believe your talking about is the same checks that this pic shows.  Same bow as above by the way.  Lol!  Josh

[SLIMBOB]

I'm with you on that.  These terms are what we bowmakers make of them for the most part.  I am certainly no expert in the use of any of these terms at all.  Suffice to say, I believe Gun Doc is ultimately right in his assessment of the problem.  If in fact the problem is a delam separating the latewood rings, it's bad news.  I finished one last year with this problem and it has held up fine to date.  I did however take 10 pounds of draw weight off it and gave it to my wife.  So 35ish pounds or so.  But it was really solid except for the very edge.

[Renacs]

Yes Eric like that last pick. Make me wonder if it's worth investing time in there sister staves. I might explore with the band saw.

[SLIMBOB]

With this one, it had spent about 9 years laying in the dirt exposed to the elements. There were multiple delams at first that I was able to cut away. This one I could not get past, but I was very near solid early wood. I had seen a delam before this but had never had to deal with one. It has held, and I feel fairly sure it will continue to hold up, but it was a crap shoot really. As I said in the previous post, it was originally at 45lbs or so. My wife kidnapped it and wanted it for 3D shoots. I took it down in weight and feel better about its long term survival. The sister stave to this one is fine btw. Every problem is searching for a solution, this one worked but most probably won't hold up in my opinion.