doing a bit more ressearch and found this:
Paul Hogue offered this method for staining arrow shafts with walnut in Primitive Archer Magazine:
"Cut an opening halfway into a green walnut, and if it is ready, the inside will be black and juicy. The nut in the center is about the size of a quarter to a half-dollar. You can pluck the nut out if it’s in your way or leave it. You'll want to put on some thin, rubber gloves, because, like I said, it’s real stain. Next, just wrap the whole walnut around your arrow shaft (or whatever you want to stain) and run it up and down. Then with a clean rag, wipe off the excess juice and particles from the wood. If you decide you want the stain darker, just do it again in a few minutes."