Black Walnut Hull Ink
The classic brown ink of medieval scribes — made from fallen walnut husks.
Boil the green husks of walnuts in water until you have a deep brown liquid, then thicken it.
- ▸The husks are loaded with natural brown stain — same stuff that ruins your hands at harvest.
- ▸Salt and vinegar keep it from going moldy.
- ▸A pinch of gum arabic makes it flow nicely from a pen.
Steps
- 01
Collect fallen walnuts and peel the soft outer hulls (wear gloves — it stains everything).
- 02
Cover hulls with water in a pot and simmer 2–4 hours until liquid is deep black-brown.
- 03
Strain through a coffee filter or cloth into a clean jar.
- 04
Reduce the liquid further on low heat to concentrate the color.
- 05
Stir in salt and vinegar; add a pinch of gum arabic if you want a glossier line.
Materials5
- — A handful of black walnut hulls (the green/black outer husk)
- — Water (enough to cover)
- — 1 tsp salt (preservative)
- — 1 tsp white vinegar (mordant)
- — Optional: gum arabic for body
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
Lightfast and historically used by Da Vinci and Rembrandt for sketching.