Pour an ounce of charcoal ash into a disposable bowl. Perform this step outside in case of spillage. You can use ash from a charcoal grill or the black ash from a wood fire.
Pour an ounce of distilled water on the ash. Pour the water slowly so that you do not splash the ash on your clothing. The resulting mixture should look like clumpy, black mud.
Mix the water and ash with a small artist's brush. Stir the mixture until all of the lumps are completely out of the ash and the bowl only contains black liquid that looks like ink.
Add one drop of vinegar to the black liquid. Stir the vinegar into the ink. This will help stabilize the ink and make it more permanent once it has dried. After you have finished stirring, the ink is complete.
Pour the India ink into an air-tight ink bottle and screw the cap down tightly. This ink dries quickly once it's exposed to air.