iron gall ink—a witch’s brew
—Shakespeare and da Vinci both used it
—You don’t want to know all the ingredients of this brew
Before pens and pencils, and typewriters and computers, a quill dipped in iron gall ink was the writing instrument and ink of choice. For some 1,000 years kings, monks, artists, poets, and everyday citizens wrote with this ink. Leonardo da Vinci penned his notes using iron-gall ink. Bach and Beethovan composed with it, Rembrandt and Van Gogh drew with it, and Shakespeare wrote his plays with the ink. The Constitution of the United States was drafted with iron gall ink.
what the heck is iron gall ink

Iron gall nuts with escape holes
Courtesy of the “Traveling Scriptorium” Yale University Library
Iron gall ink is made from gall nuts which are growths on the tree that are triggered when insects puncture tree branches where they deposit their eggs. The larvae hatch, feeding on the tree and secreting an irritant which stimulates the tree to create a growth, the gall, around the larva. The gall provides food and protection for the larva. After the larva has developed into an insect, often a wasp, it chews its way out of the gall.
Gall nuts were the source of tannin in the ink. Then a witch’s brew of other ingredients were added (or not) in varying proportions. Iron, water, urine, gum Arabic and wine or beer also supplemented the formula. Sometimes other ingredients, such as dye or pigments, salt or vinegar and sugar or honey were also added.
Obviously, since there was huge variation in the ingredients and recipes; there was no such thing as quality control. Temperatures and environment affected the oak trees, which in turn affected the gall nuts. The gall nuts were harvested at different times during their growth—affecting the color of the ink. The differences in water (its purity and whatever minerals might be present), wine and beer were also factors, as was the nature of the urine: Did the piss come from humans, goats, sheep, or cows? (Alas, I have not been able to find that out!)
i’ll give you my recipe

Recipe for making iron gall ink
From: Commonplace Book, late 17th century
Courtesy of the Beinecke Rare & Manuscript Lbrary
But golly the ink was cheap to make, and everyone was exchanging and hand-copying down the various recipes (also room for error). I can only imagine Pierre, a monk in a French monastery, sending his favorite iron gall ink recipe to Pedro in a Spanish monastery, which travelled by horseback over the Pyrenees to Spain in a leather pouch.
But no one seemed to be able to come up with anything better than iron gall ink—until the 19th century, when pencils and fountain pens began to take over, soon followed by the typewriter. Interestingly, Henry David Thoreau’s father manufactured some of the best pencils in the United States which were known for their superior quality and praised by artists and artisans. Thoreau himself worked in the father’s factory and made some technological improvements in the pencil.
what can go wrong will go wrong
Iron gall ink, however, is not kind to paper. There’s iron in the ink and humidity causes iron to rust. And a heavier ink application means more iron corrosion Possible impurities in various iron gall ink ingredients also affect paper. The ink releases sulfuric acid which travels through the paper like a Ninja warrior attacking the cellulose fibers in the paper and causing it to become brittle. When that happens, black ink turns brown. Because of iron gall ink, paper can tear, becomes brittle, or disintegrate; the ink can change color, or bleed and migrate through the paper causing more damage.
But this witch’s brew, this hodge-podge of ingredients, gave us Shakespeare’s