lamp black, iron gall, and cuttlefish
One of the most common of the early inks was lampblack, which combines the ash from burning a fatty candle with gum, or glue and water. The ink has little colour when first applied to the surface but, as it dries, it oxidises on contact with air and darkens to a deep, purple-y, black.
Carbon is chemically inert and does not fade in sunlight making the ink almost permanent.
Another ink of old was iron-gall ink, which is made from gallic acid mixed with iron salts and tannin in water and was probably the most permanent in its time.
A similar effect can be produced by putting an iron nail in a glass of water with a wasp-gall or oak-apple (the round hard growth found on oak trees – picture left) and leaving it to stand for some time on a windowsill. The liquid you are left with can be used as ink. It is the oak apple that supplies the gallic acid and the nail supplies the iron salts.
Sepia, the reddish-brown fluid probably most well known for its use in photography, is obtained from the cuttlefish and is still in use today. It provides a natural, free-flowing ink.
Modern inks are made from chemically produced gels and oils, which flow more slowly than water, and are designed to be non-clogging and permanent.