Compression fractures on the back when drying a sapling stave

[Tommy D]

 I have roughed out what I guess would be termed a “sapling” - it’s about 3 inches in diameter. It is from a tree that is a “known bow wood” here in East Africa … I believe the Latin name is Thespesia danis and it is one of the preferred woods of the Liangulu/ Wata elephant hunters.

I am trying a flat bow version and roughed the wet stave to close to floor tiller and then bent a little reflex (2-3 inches) into it to dry on a form.

I have now taken the outer (backside) bark off and have noticed some horizontal lines like little veins crossing the back of the bow.

As I have not used this wood before I can’t tell if they are just “there” or whether I induced some compression fractures on the bows back when I reflexed it.

My questions are 1) Do frets / compression fractures on a bows back matter?

2) If so could de-crowning get rid of them?

[Pat B]

Cracks across the back are deadly to wood bows because in tension it pulls the cracks open. You may try removing that back ring or even decrown the stave.

[bradsmith2010]

i dont know, has the bow been strung,, is that the sap wood layer,, is there heart wood,,under it

[mmattockx]

My questions are

1) Do frets / compression fractures on a bows back matter?

2) If so could de-crowning get rid of them?

1) Yes, that would likely blow the first time you bend it any significant amount
2) Maybe

All you can do is remove wood off the back until you get to a clean ring or clean surface if decrowning. If there is enough wood left after that to make a bow, then it should be good to go.


Mark

[Tommy D]

Are those definitely frets/ compression fractures?

[Tommy D]

i dont know, has the bow been strung,, is that the sap wood layer,, is there heart wood,,under it

It’s the layer right under the bark… no distinction that I can see between heart and sapwood.

[George Tsoukalas]

Tommy, compression fractures happen on the belly not the back.
It almost looks like you strained the stave too much too quickly.
I've never seen that amount of cracks on the back of a stave but then again I am not familiar with that wood most likely.
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Jawge

[Hamish]

Trees can get compression fractures whilst still alive. Hurricanes, big animals(maybe an elephant or rhino), or being bulldozed, could be causes. The wood is okay to use for static purposes,  like furniture, but I wouldn't be using it for a bow.

If you clean up the edge of the stave where a fracture comes out you will see how deep it runs. It will most likely be deep, removing a ring is unlikely to remedy the problem.

[superdav95]

Ya it looks suspect.  I’d be worried about how deep those cracks or fractures run.  If your still intent on making this a bow I guess you could back it with bamboo or sinew back it even.  It may not be worth it and get yourself a better piece of wood.  Best of luck. 

[Eric Krewson]

I got these on the back of a well-used osage bow, I never seen this before, the bow is a bamboo backed osage bow now.



 

[Tommy D]

I did a bit more scraping and I think that those horizontal lines are only in the bark …. Here are a few pics where I have removed the bark.

Also a picture through the section I have narrowed for the handle.

I will leave it to dry some more and see what happens. It’s a very fibrous wood.

[Pat B]

That's the cambium layer on the back. no wonder it fretted

[Tommy D]

That's the cambium layer on the back. no wonder it fretted

So you reckon we are good to proceed…

[Pat B]

Well, it depends on how deep the frets went. Sometimes cracks in the lesser layers go into the good wood. Get a good, solid back ring exposed and see it they did. If so you will have to go down another ring.

[bradsmith2010]

Im guessing there is a bow in there,,,scrape off  bark as Pat suggested and see how it looks,