Is old wood really "weaker" ???

[Richard Brekne]

Really the wrong question Thumpy... or rather not a complete enough 
one.  Lots happens to wood as it gets older.  It gets stiffer 
perpendicular to the grain particularly... according at least to a 
couple studies I've read... and in the bargain it gets brittle.  It 
looses some of its mass which you mentioned a few posts back, and its 
mass to stiffness ratio changes somewhat... again particularly of 
interest here is what happens across the grain.  Its shear strength is 
less in all axials I believe, and its compression strength is lessened. 
So is its ability to react to humidity as newer wood does... in a sense 
it becomes less reactive to taking on and giving off humidity.

None of this keeps one from reusing the panel in an RC & S assembly... 
as Del went on to say in the post you took the quotes from below.  
Indeed...  He mentioned that doing so was amoung other things not such a 
bad idea with regard to depleting stocks of good soundboard wood.

Cheers
RicB



    O.K. Here's the part I'm not convinced of :
    ( From an old post of Del's, I believe, that Ric
    kindly resurrected. )

     >     Across-grain, though, we have a problem. There
     > has been a lot fiber
     >     compression due to compression set and the old
     > wood is now much
     >     weaker across-grain than it was when it started
     > out.

       Has this been proven ? From what I've observed
    ( ever tried to drive a  nail into an old board ? )
    and Dale's comments about sparks at the sawmill, when
    cutting old boards, old wood GAINS some strength.
    So why would it be weaker ??? Indeed: If wood is
    compressed, it's also more dense, and denser
    ( usually ) means stronger. Yes, I understand some
    fibers may be crushed, but wouldn't that be offset
    ( somewhat, or entirely ) by the rigidity wood gains
    with age ??? ( Again, by oxidation of the resins
    within the cells: which eventually turns to amber,
    which is classified as a  "mineral" and "gemstone". )



    It is also
     >     considerably less resilient so we can't just dry
     > it out and
     >     compression-crown the whole thing all over
     > again.


    This I understand, 100%. If you tried to CC old wood,
    it'd probably crack, pronto !

    Thump