In the Middle Ages, black ink was either make of lampblack [carbon soot from a flame] or from oak galls of oak trees. Carbon ink is easier to make than the gall ink, but also inferior to gall ink. Carbon ink is grittier and not as permanent as gall ink. Getting soot to use for carbon ink can be done by placing a flat metal surface directly over a flame and leaving for around 10 minutes [do sit the metal on something to hold it, rather than using hands]. Soot should build up on surface and can be scraped off with a blade. The soot should become powdery and should be mixed with gum arabic [dried sap from the acacia tree]. Gum arabic can be found at a local craft store. If the ink is too thick, one might add water, but do this after adding the gum arabic. The soot does not mix well with water alone.