Iron gall ink contains three ingredients, plus water: oak galls, ferrous sulphate, and gum arabic. I used a 1770 recipe that calls for two ounces of crushed oak galls soaked overnight in one pint of water, then strained into one ounce of ferrous sulphate. One-half ounce of gum arabic is added, and the mixture stirred until it is dissolved.
You can also read an article I wrote discussing my process for copying Luca Cambiaso 1570 drawing using iron gall ink.
Written by Andrew Raftery (RISD faculty, Printmaking)
Step 1: Harvesting and Drying Oak Gall
Step 2: Crushing Oak Gall
Step 3: Soaking Oak Gall
Step 4: Adding Ferrous Sulphate
Measure one ounce of ferrous sulphate on scale. Add ferrous sulphate to oak gall solution.