[alberg30] Oak

[Robert Kirk]

At 08:44 PM 24-05-00 -0400, finnus505 at aol.com wrote:
>[...]
>White oak is more resistant to rot than red oak, primarily because the xylem
>and phloem, or internal passages that moisture and sap traverse in the living
>wood, of the white oak are interupted, while those of the red oak are
>continuous through the wood, and so are a better passage for fungi in the cut
>wood
>however, many other hardwoods, such as ash or hickory, are more rot resistant
>than oak. [...]


My old  Marks Mechanical engineering Handbook agrees that amongst the 
domestic woods, white oak is pretty rot resistant.  Cedar, cypress, 
redwood, black locust, & black walnut are better. But they're not exactly 
construction woods. Douglas fir, white pine, yellow pine, & red gum are 
comparable, while the rest are relatively more rot prone, including red 
oak. Kent's agrees that ash & hickory are in this lower group along 
with  red oak. The real losers are aspen, cottenwood, commercial white fir, 
& willow.

The important thing to remember is that you must have heartwood to be rot 
resistant. Sap wood is useless.

Wood rots best at ~ 25% moisture. Dry wood and saturated wood won't rot, 
but the cellulose will eventually dissolve out of saturated wood, but at a 
longer time scale than our boat lives.

Speaking of yellow pine, that's a remarkably rot resistant wood. I've seen 
hundred year old houses when I lived in Louisiana which were supported on 
their original native yellow pine posts with no trace of rot. Heartwood. of 
course. Wonder why they didn't make boats of it? Probably because cypress 
was so handy along the bayous.

Bob Kirk
Isobar #181
  

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