THE RARE BOOKS CURATOR places a small volume on a cradle. I’ve come looking for landscapes in the library. This thirteenth-century book contains an entire ecosystem. The tissue-thin parchment, made from either sheep or goatskin, is pocked with irregular holes: the traces of medieval insect bites. The book’s wooden boards are covered in calf. There are minerals in its miniature illustrations and plants on its pages. The brown ink of the handwritten script was forged from iron mixed with oak galls, those woody baubles produced by a tree in response to a parasitic insect’s injection of eggs. Rather than discourage the intruders, though, the hard-shelled galls provide a protective home for larvae growing inside. These tannic spheres were used around the globe for tanning leather, making medicines, and making ink.

The book is metamorphosing too. Over the past six hundred years, the ink has eaten away at the letters, leaving more holes and halos. Today it looks as if the heart of each letter has gone up in flame and these are its charred remains. When it was first developed, iron gall ink was preferred for its permanence. Its ancient precursor, carbon ink, sat on top of a sheet and could be rubbed or washed away. But as the book conservator Kimberly Kwan tells me over lunch one day, iron gall ink “bites” into its support. In a perfect recipe, the ink can be very stable, but any imbalance releases free iron ions, which do more than bite. They devour. Researchers have been aware of the threat to documents written in iron gall ink since at least 1765. But the iconic brown ink remained popular well into the twentieth century. Writers loved it for its color, its easy availability, and for those who didn’t yet know otherwise, its longevity.

Want to keep reading?

Subscribe and help keep Orion independent, nonprofit, and ad-free.

Subscribe Now

Already a digital subscriber? Sign in here.