spalting question -- bubbling black pockets of white stuff

Subject:	spalting question -- bubbling black pockets of white stuff
Date:	Mon, 4 Jan 2010 23:00:46 +0000 (UTC)

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