This is a butternut salad bowl that we've used since 2014. Recently we noticed a black spot on the base of the bowl. I removed most of the black with sandpaper. It looks like it was a small knot that started to take on moisture and mold or something.
The finish is a mixture of walnut oil with a little bee's wax and carnuba mixed in.
Anxious to hear what your thoughts are regarding a fix. Thanks.