Permanence is easy to claim and harder to show — so we show our work: what goes in, how it's made, and the gates a batch passes before it earns a label.
Our Oak Gall is a Theophilus-derivative — the 12th-century recipe of galla, vitriolum, gummi (oak gall, iron, gum) — with four modern concessions we'd rather name than hide, and one historical addition:
A botanical preservative — thyme (thymol) and clove (eugenol) — for shelf stability. Glycerin, a humectant, so the ink doesn't dry in the feed. A trace flow agent so the ink moves cleanly through a fountain-pen feed instead of dragging. pH-adjusted distilled water, so the chemistry starts where it should. And the historical one: an indigo sighting blue — indigo carmine, soluble indigo — so the line is legible the moment you write it, exactly as the nineteenth-century blue-black inks did it. The indigo shows you the line; the iron makes it permanent. Everything else, Theophilus would recognize.
Read on a calibrated meter at day two. Oak Gall must fall in 2.1–2.6: lower bites pens and paper, higher under-develops the color and the permanence. Out of band, it's corrected on a test sample or discarded.
Written on Tomoe River and watched over 24 hours. It should darken to a clean blue-black with no greenish cast and no drift toward red or brown.
Run on cheap copy paper, the hardest test for feathering. Dialed right, the line is smooth and wet with no feather bloom and no nib creep — or the flow agent gets adjusted next batch.
Every recipe is tested in a Pilot Metropolitan (feed-clogging-prone), a TWSBI Eco (modern piston), and a vintage Esterbrook (sensitive seals). Flushed after each. No feed clogging after 20 minutes idle.
No bottle ships until a 14-day quarantine clears: a daily check for mold, pH drift, sedimentation, and color shift. If anything's off, the batch doesn't ship — full stop.
Each batch gets a number and a logged record — pH, dates, observations, pen results. The specimen card in your box is written from that same batch, at the desk where it was mixed.
Oak Gall is iron gall — mildly acidic (around pH 2.4). It's safe in modern steel-nibbed fountain pens; flush after extended use. We don't recommend it for vintage gold-nibbed pens without acid-resistant feeds. Walnut is gentle and safe in any pen. Lampblack is pigmented — shake before filling, and flush after a couple of weeks idle. We say all of this on the label, too. If an ink can't pass these tests, we don't sell it as a fountain-pen ink.
As the first batches clear quarantine, the specimen cards and batch notes go up here and on Instagram. Leave an address to follow along — and to know the day the first bottle is ready.
Target ranges and methods live in our working formulary; we publish the results, not the trade secrets we don't keep.