Does anyone know what kind of dye is used to color the throat of a powder horn? Some horns have a naturally darker inner layer and by scraping, etc this can be revealed in the spout area. There are however a lot of horns that look like they are dyed dark brown in the spout area. I suppose India Ink would work but I was wondering if the dye would leach out in time or if it would seep into other areas of the horn.