Black Walnut Ink
Walnut ink is an ink made from the green husk surrounding the nut of walnuts. It can be made yourself or is widely available online. The black walnut Juglans Nigra is commonly used. The ink, dye or pigment may be liquid or made of crystals that are mixed with water before use. It can be used to produce for all forms of dyeing and for the creation of a very dark natural ink.
Here featured with a black walnut ink made by artists de Onkruidenier during their residency at the Jan van Eyck Academie.
De Onkruidenier (Article)