Chuck said:

Greg,

I know you don't know me from a hole in the wall, but FWIW to you, I
think I would go along with the spalting crowd. There's a reason for
that, though. The "bullseye" effect in some of the larger "colonies"
look just like mold growing in a petri dish and the fact that the
smaller discolorations seem to very closely follow the curve of the
grain.

It could very well be, especially since this is a veneer, that the
blade used to cut it originally, transferred spores to the surface of
the piece you have here. Perhaps the chlorine in the water you used
to experiment was enough to inhibit the growth of the spores, and the
moisture in the glue, coupled with the sealing with plastic wrap,
provided the optimum climate for awakening the dormant spores.

Pretty good theory. Although in person the spots look more like black
ink that mold stains. Mold is something we have all too much of here
in the humid south, and I've seen a lot of it. The pattern of spots
does look like mold, but I'm not entirely sold.

It turns out that there are some odd salts in/on the makore, crystals
of it are visible in the grain. I am becoming more convinced that it
is a chemical reaction, rather than mold. I have some test setups
going, as time permits, to determine exactly what this is - for
certain. It seems that clamping pressure after gluing is the major
contributing factor as to whether the discoloration appears or not.

I tried de-chlorinated aquarium water and could not provoke the growth
of mold. I also tried glue by itself, and also could not provoke the
growth of mold. But if I clamp with a lot of glue, and the glue
squeezes through the makore veneer into the maple veneer, I get spots
within 30 minutes - awfully quick for mold - especially in winter.

I hate to throw out 20 sq ft of makore veneer due to this phenomenon.

For me, the jury is still out on this one...

Thanks for the input,

Greg G.