IAM interested in the article ‘How galling’ (August 10), but would like another on galls as a source for ink. I was surprised it wasn’t mentioned. My understanding is that galls, especially oak, provided the main if not only source of ink for many centuries. Jeannette Harper, by email Ed—you’re quite right. Iron-gall ink, made from crushed oak galls soaked in water (or sometimes wine), ferrous sulphate and gum arabic, is one of the most frequently found inks in manuscripts from the Middle Ages to the 19th century.