A Brief History of Writing Instuments - Ink and Letters: "The Romans created a reed-pen perfect for parchment and ink, from the hollow tubular-stems of marsh grasses, especially from the jointed bamboo plant. They converted bamboo stems into a primitive form of fountain pen. They cut one end into the form of a pen nib or point. A writing fluid or ink filled the stem, squeezing the reed forced fluid to the nib.
By 400 A.D. a stable form of ink developed, a composite of iron-salts, nutgalls and gum, the basic formula, which was to remain in use for centuries. Its color when first applied to paper was a bluish-black, rapidly turning into a darker black and then over the years fading to the familiar dull brown color commonly seen in old documents."
I was also surprised to learn that the iron stylus Romans used with wax tablets was called a graphium.
“The stylus was also termed graphium (Ovid. Amor. i.11.23; Suet. Jul. 82), and the case in which it was kept graphiarium (Martial, xiv.21) or graphiaria theca (Suet. Claud. 35).
I wonder if this influenced our name for pencil lead – graphite?