Timber fractures?

[benldwyer]

Hi All,
I bought some PNG rosewood recently and when I received it I found cracks/fractures running across the grain, just wanted to know if the timber is now fire wood... and what the correct term for these faults?
Thanks
Ben

[Trevor Gore]

Those are typically called brash fractures and are typically caused by the wood failing in compression, usually on the compression side of a bend, so they sometimes get called compression cracks. Clearly, it weakens the wood considerably, leading to early failure when the the compression crack sees tension (i.e. when the bending force is reversed). So whilst compression cracks can occur in a standing tree (for example due to wind loads), it is unusual for the tree (or branch) to remain standing as the bending reverses as the tree sways. So likely the most frequent cause in processed lumber is due to impact when the tree is felled.

In high stress components compression cracks can appear in use and look much the same as brash cracks (because they are, basically, the same). When I was building (and using) wooden masts on sailboats, typically made of spruce, eventually cracks wood appear on the aft side of the mast, because that side was usually in compression when the sheet loading was high, when sailing to windward. If the aft side then saw tension loads, it was goodbye mast.

I'd be reluctant to use that wood on high stress components (most of an acoustic guitar) but you could likely get away with it as part of the body on a solid body electric.

[kiwigeo]

If this wood was sold as tonewood I'd definitely send it back to supplier. If sold by a general timber merchant you can probably still argue its not fit for purpose for structural purposes

[benldwyer]

Thank you Trevor and Martin, very detailed. I had found some info about compression fractures but had not heard of brash. I had purchased for acoustic necks so will either repurpose somehow or return.
Thank you again!