Oak Gall Iron Ink
The ink of the Magna Carta and Bach's manuscripts.
Soak oak galls (little nut-shaped wasp homes on oak leaves) in water, then add iron — the liquid turns instant blue-black.
- ▸Oak galls are full of tannin, the same stuff in strong tea.
- ▸Tannin meets iron and a permanent black color appears in seconds.
- ▸This is the same recipe used for legal documents for over a thousand years.
Steps
- 01
Crush oak galls and soak in water for 1–2 weeks, stirring daily.
- 02
Strain the tannic liquid into a clean jar.
- 03
Dissolve gum arabic in a little warm water and add to the tannin.
- 04
Slowly stir in iron sulfate — the liquid will turn deep blue-black instantly.
- 05
Bottle and let mature for a few days before use.
Materials4
- — 20 g crushed oak galls (wasp galls from oak trees)
- — 10 g iron sulfate (or rusty nails soaked in vinegar)
- — 5 g gum arabic
- — 200 ml rainwater or distilled water
Safety
Involves caustics, acids, or open flame. Full PPE and trained supervision recommended.
- Acidic / corrosive etchant
- Airborne dust — respiratory irritant
- Dye mordant — skin and stain hazard
- ☐Wear goggles, apron, and acid-resistant gloves
- ☐Always pour acid into water, not the reverse
- ☐Neutralize and dispose per local hazardous-waste rules
- ☐Wear an N95 / FFP2 mask when handling dry powders
- ☐Mix in a tray to contain dust; wipe surfaces wet
- ☐Wear gloves and an apron — stains are permanent
- ☐Use dedicated pots, never cookware
- ☐Work in a ventilated area; keep food and drink out of the studio
- ☐Read each material's safety data sheet (SDS) before starting
- ☐Have water, soap, and a first-aid kit accessible
Heuristic guidance derived from listed materials. Always consult each material's safety data sheet (SDS) and a qualified instructor before attempting.
Notes
Highly permanent; the oxidation continues on paper, deepening over years.