K, thanks. The reason I asked about the vitamin C is that the tablets have fillers in them like ascorbic acid and other stuff I can't recall. I was afraid they might alter the tincture negatively in some way.
I asked about the yellows ones because I found a few that were in good shape with no blackening of the hull. I managed to get a good amount of green ones although I left the ones that had some sort of damage to the hull that wasn't just blackening (like some sort of insects had ate away parts of it).
I'll have to wait til next season to get fresher ones, I hadn't heard of Black-Walnut tincture til just recently so have to make due with what I can get now. :P