charisstoma

Oak apple or oak gall is the common name for a large, round, vaguely apple-like gall commonly found on many species of oak. Oak apples range in size from 2 to 4 centimetres (1 to 2 in) in diameter and are caused by chemicals injected by the larva of certain kinds of gall wasp in the family Cynipidae.[1] The adult female wasp lays single eggs in developing leaf buds. The wasp larvae feed on the gall tissue resulting from their secretions, which modify the oak bud into the gall, a structure that protects the developing larvae until they undergo metamorphosis into adults.

Oak galls have been used in the production of ink since at least the time of the Roman Empire. From the Middle Ages to the early twentieth century, iron gall ink was the main medium used for writing in the Western world.

Gall nuts are a source of tannin in the production of iron gall ink. Tannins belong to a group of molecules known as polyphenols and can be taken from different parts of plants such as leaves, pods, fruits, and gall nuts.

Along with gall nuts, other important ingredients in the production of iron gall ink include iron sulfate and gum arabic. The reaction between the tannins from the gall nut and the iron produces a complex that gives the iron gall its color. The gum arabic makes the ink more viscous and helps bind the ink to the writing surface.

How to make Ink

There are different ways of making ink from galls but this method is quite straight forward.

Firstly take some steel wool and place in a small container and cover with some vinegar (cheap malt vinegar is fine) or lemon juice and allow to sit for a few days to allow the iron to dissolve.
oak apple ink 1

Take a couple of good handfuls of oak galls and break up into small pieces.
oak apple 2

Place in a pan and cover with water. Bring to the boil and simmer for 20-30 minutes until you get a nice dark brown solution as all the tannins are released.
oak apple 3