EJ, Just curious, what species is the "local" walnut in Chile? I have read that fiddleback is most prevalent in Black Walnut, and that no one knows for sure what causes it in a tree. But supposedly a tree that has it will exhibit that grain structure throughout the tree to the smallest branches. I see a lot of it in Claro and very little in English. Last summer I bought a full pick-up load of very nicely figured Pennsylvania Black Walnut slabs that I got to hand pick out of a large quantity. Only a couple pieces had any fiddleback.
