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Old 09-14-2021, 12:44 PM
redir redir is offline
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Join Date: Aug 2011
Location: Mountains of Virginia
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Originally Posted by Alan Carruth View Post
Lotsa variables.

I don't have any test data on Torrefied spruce, and only limited data on 'old' wood. Hemicellulose degradation is said to reduce both the density and Young's modulus of wood, with the density falling a bit faster, so that overall the Young's modulus/density ratio goes up a bit. If Torrefaction works the same way that would tend to produce a top that is lighter at a given stiffness, all else equal, but the top itself would need to be a bit thicker than an un-treated one. It's similar to swapping in a low density piece of wood, such as WRC, instead of an average piece of, say, Red spruce.

The question I don't think we can answer yet is whether the Torrefied top will see greater long-term creep, or less, as compared with a non-Torrefied top of the same species if both are worked to the same thickness and braced the same. It should be possible to do some experiments over a period of a year or two that might be able to address that if you have access to a lot of cut offs of tops. You could make a bunch of go-bars of the same size, spring them in into a deck of some sort, and leave them. Take them out after six months or a year and see how much of a 'set' they've taken, and whether they relax back to straight over time.
So if one does deflection testing and say for example they found that for any average piece of spruce on an OM build that a deflection of .25in gives them the sound they want, would they want to make the T-top deflect less (hence generally speaking thicker) to achieve the same desired tonal palate? Given that all the tops are around average and not unusually stiff or unusually floppy.
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