On Mon, 4 Jan 2010 17:00:46 -0600, Andrew Barss wrote
(in message ):



I was reorganizing a shed yesterday, and came across a large piece of
spalted bigleaf maple I bought three or so years ago from a guy in
Washington State (I live in Arizona). One side, and two endgrain ends, of
the block (it's big, 22x22x7) had a strange appearance. When I looked at
them more closely, the areas of black spalting (in this piece, as well as
a couple others, there are contiguous patches of black, rather than the
nice spidery lines we all love) had "bubbled" -- there were blisters
sticking up off the surface 1/8" to 1/4" high, anywhere from 1/4" to 1"
across. They're hard, and when I cut through them with a knife (it
appeared to be a thin shell of wood forming the bubble), what appeared
inside was white, and although it was hard, it crumbled easily.

What is this? Is there any concern about this being a nasty form of
spalting I should avoid, or is it safe to turn?

Thanks,

Andy Barss


Spalting is the name given to the staining or marking caused by the earlier
stages of rot. Like a mushroom, rot is the work of fungal growth. Like a
mushroom, the conk or other fungus growth you see on the outside of the tree
is the "flowering" or "fruiting" body of the fungus, and it produces the
spores which are analogous to seeds from a flower. The fungus grows from
spores, just as a flower grows from seeds. It is the spores that you do not
want to get into your lungs - same precautions you take in not stirring up
the moldy guck in a damp basement or fungus-laden insides of badly vented
walls... you don't want to inhale the spores. That said, the fine dusts that
we generate as turners can be an irritant to some people. Some people will be
sensitized to these dusts, and get allergic reactions. Some kinds of wood
have a more pronounced effect than others. There are, in fact, lots of
websites out there addressing this specific issue, sensitivity to various
wood dusts, by species. Some can be very toxic, in fact. I cannot say which,
right now. In my own case, I work with what I get locally, pine, birch, and
aspen. Pine and aspen will dry nicely with the bark on. Birch will not. Birch
bark is waterproof and will hold the moisture inside, only allowing the wood
to dry from the ends, so it rots easily and quickly. On the other hand, it
can be turned with the bark on and the inside of the turned objet then
permits drying of the wood that may still have a patch of birch bark on it.
There is nothing wrong with wearing a decent dust mask. If you want, you
could actually vigorously wash the block of wood in question, to remove any
loose material that you are uncertain about. I am not a doctor, nor do I play
one on TV. These remarks are my own observations and are based on my own
reading on the subject. There are no guarantees. In my own case, I'd wash the
wood, and get to work.
I tied into a piece of birch that was a bit too far gone for my skill level,
too many places of soft punky rot in the block, and so it will go into the
fireplace.
tom koehler

--
I will find a way or make one.