I have never heard of, let alone seen spalted walnut..
That is until some boards stored incorrectly got wet and started to grow fungus…
The boards in this photo do not have spalting.
Or very little…then there are these..
This last pic is of a thicker board that was resawn on the bandsaw and bookmatched..
NB this is European Walnut..
-- Drink twice... and don't bother to cut... @ lazylarrywoodworks.com.au For lovers of all things timber...