ferric gallate

Ingredients

tannic acid, oak galls, Aleppo gall, marble gall, apple gall, iron sulfate, vitriol, copperas, rainwater, wine, beer, vinegar, gum arabic

Preparation Steps

Original Recipe Text

The four fundamental components are a tannin source, iron source, solvent, and binder (p. 13). Tannic acid is a polyphenol derived from plant leaves (e.g., sumac) or woods (e.g., oak, mahogany) (p. 13). Oak galls, specifically Aleppo, marble, and apple galls, are used for their high tannin concentration (p. 15). Iron sulfate (vitriol/copperas) is the second essential ingredient (p. 16). Solvents such as rainwater, wine, beer, or vinegar suspend the solids (p. 18). Gum arabic, a sap from Africa, India, or Australia, is used as a thickening agent, added as a powder in the final steps (p. 19-20). The addition of gall and metal sulfate to the solution creates a fine black precipitate which is then stabilized by gum arabic to form a viable ink (p. 18-20).

Evidence

"Ink samples were made to simulate the ink on ancient manuscripts for UV-vis and fluorescence spectral analysis. ... Thermographic imaging was performed on the same ink on parchment samples."

Remarks

The study analyzed simulated inks to understand chemical properties. It notes that impurities in vitriol like copper, zinc, and aluminum can affect ink quality; copper sulfate specifically produces soluble brown ink (p. 17). Ink makers used iron strips to increase iron content and mask metal impurities (p. 17).