Re: Unpainted wood.

Anthony Thompson <thompson@...>

In an interesting post, Denny Anspach wrote:
Rot will not occur in the ideal environs of wood of 30-35% moisture
content. It will not occur, or be arrested in the wettest of environs,
or if the wood moisture content is <20% . It will not occur in
environs >105º nor <40º. It will not occur, or be severely inhibited
in low oxygen conditions.
The last of these conditions is crucially important. Low oxygen
or anaerobic conditions will allow wood to survive indefinitely, as the
rotting process requires available oxygen. This is not, of course, the
condition underneath freight car floors or running boards, but it is
important if we consider wood in other environments.

. . . 1000-1200 year old intact Viking ships have been found
completely intact buried deep in the wettest of mud at Gokstad in
Norway and Roskilde in Denmark.
Again, what is important here is that these are
organically-rich muds, in which the surplus organic matter consumes all
the oxygen (which is not then replenished), permitting the wood to
last. But the time scale noted is not as impressive as the small twig
which I have before me as I write: it was found in a mud core from a
small tarn above Echo Lake in the Sierra, resting atop the orange ash
layer from the Mount Mazama (now Crater Lake) explosion of 6600 BC. It
is a bit shrunken but in no way rotted.
It ain't all about creosote.

Anthony Thompson
Dept. of Materials Science & Engineering
University of California, Berkeley

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