Mike, when you do the porosity test on different woods, be sure to test
red alder.  It looks like a more porous wood than most but when it's
sealed correctly it seems to be almost 100% airtight.

I think the key is sealing the wood effectively with a method that will
last for a long time.  I've used different sealers, but so far I'm a
fan of paraffin wax.

It would be nice to hear more discussion about long term effectiveness
of wood sealers.

Brian Smith