What the Ink Becomes

Iron, Oak, and Fourteen Hundred Years

Oak gall

I was doing trail maintenance at Gold Creek Nature Preserve — land maintained by the Los Angeles Community College District for faculty, staff, and student research — when I found them. Dried. Still on the branch. Each one about the size of a ping pong ball, hard on the outside and powdery within, each one with a clean exit hole where something had left. I knew what they were. I put ten of them in my pocket and kept working.

Oak galls. The exit wound of a wasp larva that had spent its entire early life inside a growth the tree made around it — a structure the tree built to contain something it couldn’t expel. The wasp is gone. The gall remains. Inside the dried tissue: tannic acid, iron compounds, and a chemistry that the Western world used to write down everything it believed was worth keeping for roughly fourteen hundred years.

The powder inside those galls is partly crystalline — gallic acid breaking down from the gallotannins, forming colorless needles as the structure collapses after the wasp leaves. I had crystals in my pocket on that hillside without knowing it. The ink begins before the ink begins.

I am a mineralogist. I also practice calligraphy, and I have spent years studying how letterforms change — how a mark made in the first century becomes something subtly different by the fifth, unrecognizable by the fifteenth, and then transforms again in the hands of someone working today who has decided the letter doesn’t have to look like anything that came before. My friend Jason Logan at the Toronto Ink Company had been in the back of my mind for months. Jason forages all over the world — walnut husks, rusty nails, goldenrod, whatever a city offers up — and his book Make Ink had made me want to find my own source material. The galls were golf ball sized, hard on the outside and powdery within, each one with a clean exit hole where the wasp had left. I put ten of them in my pocket and kept working. If you want to try this yourself, start with Jason’s book.

For one thousand four hundred years, the Western world wrote itself down in iron.

Every document that shaped how we understand law, science, faith, and music was made from the same recipe: tannic acid from a wasp’s nursery, melanterite — a hydrated iron sulfate mineral pulled from the ground and dissolved into solution — gum arabic to control viscosity and bind the ink to the page, and water. The Lindisfarne Gospels, copied by a monk named Eadfrith on a tidal island off the Northumberland coast around 715 CE. The Magna Carta. Leonardo’s notebooks. Bach’s cantatas, written in his own hand before the music was ever performed. Galileo’s notes on motion — scientists have since used the iron concentration in different ink batches to sequence the order he wrote them. And Isaac Newton, who mixed his own iron gall ink from oak galls, gum arabic, copperas, and beer, wrote the recipe in his laboratory journal and added a note at the bottom: With this Ink new made I wrote this.

Manuscripts with iron gall ink on display at the Getty. Photos by me.

Sumi and other carbon-based inks are pigments — fine particles of carbon physically trapped between the collagen fibers of parchment. They don’t react with the skin of vellum. A pumice stone could dislodge them, lifting the carbon free, leaving the vellum surface intact and ready for new text. This is how palimpsests were made — the same skin written on, erased, and written on again. The Archimedes Palimpsest. The Sinai Palimpsest. Centuries of reused vellum, the old text ghosting beneath the new.

Iron gall ink chemically bonded with the collagen fibers of the animal skin. Pumice couldn’t touch it. Repeated scraping damaged the vellum. Acidic washes were tried and rarely worked completely — the ghost of the mark remained in the skin long after the surface was gone. The monks chose this ink precisely because it could not be undone.

Modern Chinese calligraphy with Sumi ink. As on display at the Huntington Library. Photo by me.

There was something else. Fresh iron gall ink is a pale grey solution that looks like weak tea. Within minutes of hitting the page, as the ferrous tannate complex oxidizes in air and converts to ferric tannate, it darkens. Purple-grey first, then deep black. The scribe watched the words arrive. Carbon ink gave you exactly what you put down. Iron gall gave you a mark that developed, that committed, that declared itself permanent by becoming darker as it dried.

What the monks did not know — what nobody knew until conservation scientists began examining degraded manuscripts in the twentieth century — is that the same chemistry making the ink permanent was also, slowly and inevitably, destroying the substrate it had bonded with. The document and its destruction are the same reaction on different timescales. The monks writing the Gospels were simultaneously preserving and consuming them. They just wouldn’t live long enough to see it.

The destruction was the cost of that permanence. For centuries it was a cost nobody knew they were paying.

Nobody handed the medieval scriptoria a user manual.

The recipes that survive — and many do, collected in dedicated treatises and recipe books copied across centuries — are not instructions so much as field notes. The first known reference to iron gall ink appears in Martianus Capella’s encyclopedic work on the seven liberal arts, written in Carthage around 420 CE — a passing mention of a mixture of galls and gum, enough to know the ink existed, not enough to make it. The full recipes come later. Theophilus, a twelfth century monk, dedicated an entire treatise — De diversis artibus — to the arts of painting, glassmaking, and metalwork, including detailed ink recipes. The Compositiones ad tingenda, an eighth century compilation, is the earliest known recipe collection in the Western tradition. By the Middle Ages the recipes are everywhere, each one a report from someone who found a ratio that worked and wrote it down before they died.

The proportions vary from monastery to monastery, century to century, one scribe’s hand to the next. Some monks used wine instead of water. Some used beer, as Newton did six centuries later. Some added vinegar to accelerate the iron reaction. Some steeped the galls for days, some for weeks.

Every variation was an experiment. None of them called it that.

What they were tracking — without instruments, without chemistry, without any framework beyond observation and result — was the same set of variables a conservation scientist tracks today. Iron concentration. Acidity. Viscosity. The ratio of tannin to iron that produces a stable, dark, permanent mark without accelerating degradation so fast the document fails within a generation. They were optimizing a chemical system by hand, recording their results in the system itself, and passing the knowledge forward through apprenticeship rather than publication.

Homemade iron gall and J. Herbin 1670 Rouge hematite on hot-pressed watercolor paper, calligraphy by me.

When you write with iron gall, you put the mark down pale. Grey, like weak tea dragged across the page. Then you watch it happen. Within seconds — not minutes, seconds — it darkens. The ferrous tannate oxidizing in air, converting to ferric tannate, the iron committing to its new state. By the time your eye travels back to the beginning of the line you just wrote, the beginning has already changed. The mark is declaring itself while you’re still making it.

No other medieval ink does it. No other ink makes the commitment visible in real time quite like it.

I have studied ancient handwriting from the first century forward — how a letterform shifts across decades, how a hand trained in one tradition carries its habits into another, how the same letter looks different cut in stone, brushed with carbon, pressed in type, or drawn with a nib on vellum. What I keep returning to is this: the calligrapher working in iron gall is never working with a finished material. The ink is in process. The letter is in process. The hand adjusting viscosity for humidity, testing flow on scrap before committing to the page, watching the mark arrive rather than simply appear — that hand is doing what every empiricist does. Observing a system. Adjusting variables. Waiting to see what the material decides.

The historical calligrapher mastering a dead script and the contemporary lettering artist pushing a letter until it stops being legible are doing the same thing — testing what a mark can carry before it breaks. The monks were doing it too. The instrument changes. The question doesn’t.

Calligraphy is not static. It never was. The letter itself is not static. The ink least of all.

The ink never stops reacting.

This is the part nobody told the monks. When the pen leaves the page the chemistry doesn’t stop. The iron tannate complex that makes the mark permanent continues to interact with the vellum, with the oxygen in the air, with the moisture in the environment, with the trace metals in the ink itself. The manuscript sitting in a library archive is not a static object. It is a slow chemical system. It has been running the same reactions for centuries. It is still running them now.

The degradation happens through two mechanisms working simultaneously. Iron gall ink is highly acidic — pH between 1 and 3 — and that acidity attacks whatever substrate it contacts. On parchment it degrades the collagen structure of the skin. On paper, which became the dominant substrate as iron gall ink spread beyond the scriptoria into secular use, it hydrolyzes cellulose chains, making the paper progressively more brittle until whole sections along the written lines simply fall away. The second mechanism is more aggressive. The iron ions in the ink drive a Fenton reaction — a free radical process that generates hydroxyl radicals, among the most reactive oxidizing agents in chemistry. These don’t corrode the surface. They break molecular chains at the microscopic level, shredding the cellulose from the inside.

Iron gall ink that I made. Note dendritic crystals forming around the edges. The brown color change spots were from me trying to change the pH while the ink was on the paper.

Rusting is the closest common analogy. But rust sits on the surface and slows itself down as it builds up. Iron gall ink degradation doesn’t slow down. The Fe²⁺ ions that drive the Fenton reaction are continuously regenerated in the cycle — the reaction feeds itself. And as cellulose breaks down, it produces acidic compounds that further accelerate hydrolysis. The two mechanisms reinforce each other. The manuscript becomes more vulnerable as it degrades, not less.

And there is one more thing the monks couldn’t have known. The villain isn’t primarily the iron. It’s the copper — trace impurities in the green vitriol, present in every historical batch of iron sulfate, invisible to any instrument available before the twentieth century. Copper is a more powerful Fenton catalyst than iron. The purity of the raw materials the scribe used to make his ink determined the fate of the manuscript he wrote. A batch of green vitriol from one mine versus another. The difference between a manuscript that survives eight centuries and one that eats itself within two.

As the ink ages, it mineralizes.

The iron sulfate migrates through the paper fibers and crystallizes. Conservation scientists examining manuscripts from the fourteenth through seventeenth centuries using XRD and Raman spectroscopy have identified the mineral assemblage forming inside them: melanterite, rozenite, copiapite, amarantite, jarosite, iron oxalates. Named mineral species. The same minerals that form in acid mine drainage. The same minerals that form on the walls of abandoned mine shafts. The same minerals that NASA’s instruments have identified on the surface of Mars as evidence of ancient acidic water.

The gum arabic contributes its own minerals. Over centuries it breaks down through glycine degradation, producing oxalic acid that reacts with whatever cations are available — calcium from the paper filler, iron from the ink, copper from the trace impurities — crystallizing as calcium oxalate, iron oxalate, copper oxalate. The ingredient added to make the ink flow and adhere to the page becomes, over time, a second wave of mineral crystallization inside the document. The binder unmakes what it helped make.

A mineralogist reading the assemblage in a degraded manuscript can determine its degradation state the same way a physician reads a blood panel. Calcium and iron oxalates in low concentration, pH above five — early stage, recoverable. Magnesium and ferric oxalates — severe degradation, the document in the late stages of its conversion from record to mineral deposit.

I have the instrument to read this. Raman spectroscopy can identify every one of these phases non-destructively, without touching the document. I have iron gall ink made from galls I found on a Los Angeles hillside. I have not yet run it aged through the instrument. That is the next step.

What I already know is this: the manuscript the monks wrote to last forever is becoming something else. Not decaying — transforming. The words are still there. The minerals are forming around them. The document is doing what minerals do — responding to its environment, recording its own history in its crystal structure, becoming a different kind of record than the one the scribe intended.

The Lindisfarne Gospels are mineralizing. Bach’s cantatas are mineralizing. Newton’s laboratory notebooks, written in ink he mixed himself from oak galls and beer, are mineralizing.

The words are becoming stone.

I make the same ink. From galls I found on a hillside in Los Angeles, the same chemistry the monks used, the same minerals forming in the jar on my desk. I write with it. I sign my name with it. I named this publication with it.

Look at the name of this publication.

The Ρ is the Greek letter Rho — the second letter of Christos. It has always been there. And next to it, the letter most people read as an X.

Not an X. The Greek letter Chi — the first letter of Christos, the Greek word for Christ. Together they are ΧΡ — Chi Rho — the oldest sacred monogram in the Western world, the abbreviation early Christian scribes used for the name they considered too holy to write in full. When you see it in Pocketful of Χtals you are looking at that monogram, reversed. When you see it in Χmas you are not seeing Christ crossed out. You are seeing Christ written the way a sixth century monk would have written him — in the oldest shorthand for his name that exists in the written record.

The monks who copied the Gospels in iron gall ink did not begin their manuscripts with the first word of scripture. They began with the Chi. A single mark, written before the text each day. The start of a prayer compressed into a letter. The acknowledgment that what followed was not their work but something they were vessels for. The Chi came first. Everything else came after.

This is the nomen sacrum — the sacred name. Early Christian scribes developed a system of abbreviations for the names they considered too holy to write out in full. Christos became ΧΡ — Chi Rho — or simply Χ. The practice spread from the earliest Greek manuscripts through the Latin scriptoria of medieval Europe. Constantine put it on his battle standard. It appeared on the walls of Roman catacombs. It is on the Lindisfarne Gospels, on the Book of Kells, on every manuscript Eadfrith ever touched. It is the first mark the scribe made. And it could not be erased. Carbon ink could be scraped from vellum with a knife — the text recovered, rewritten, repurposed. Iron gall ink bit into the skin of the animal and became it. The Chi written in iron gall was permanent by the same chemistry that made it sacred. The monks chose this ink because the permanence of the material matched the permanence of the name. The knife that could erase everything else could not touch it.

The letter was never lost. It was just waiting for someone to look at it.

I named this publication pocketful of χtals knowing what that letter was. Chi — the scientific shorthand for crystal, and the oldest sacred abbreviation for Christ in the Western written tradition. The monks who wrote it in iron gall ink before beginning their manuscripts knew it as the second.

Iron gall inked glass wing butterfly with J. Herbin 1670 Emerald of Chivor with real gold particles on hot-pressed water color. Made by me.

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I am the Curator of Mineral Sciences at the Natural History Museum of Los Angeles County, adjunct professor at USC, and former affiliate research scientist at NASA-JPL. I have studied ancient handwriting and manuscript traditions at Berkley. I make my own inks, including iron gall. I’ve enjoyed doing many forms of calligraphy from ancient uncials to modern letter forms.