Commercial stains have been around for about 100 years, but woodworkers have stained wood for centuries using pigments and dyes made from plants and minerals. You can make fairly simple stains at home and use them to give wood a distinctive look.
When experimenting with homemade stains, measure and carefully record all of the ingredients used. This will allow you to duplicate the same color of stain later. Without a record of how you prepared the stain, it would be nearly impossible to create the same stain twice.
For a dark gray or ebony stain, soak iron nails in a jar of vinegar for several days. Once the vinegar has darkened, pour off some of the liquid, and brush it onto a test piece of wood. The results will not initially be dramatic, but as it dries, the wood will turn silvery gray or with additional stain, almost black.