This process is similar to making iron gall ink, but in this method, the tannins from acorns supply the pigment, as opposed to a traditional oak gall. Oak gall ink has a storied historical presence and was the most utilized ink for approximately 1,400 year. The acidity of this ink has proved to be problematic, in an archival sense, but it's significance absolutely fascinating and I very much enjoyed creating my own ink.
I harvested acorns from an oak tree my uncle planted in the early 1970's in my hometown to work with in the ink making endeavor!
I submerged the acorns under rainwater in a small crockpot and then I proceeded to essentially cook them for 3 days.
After the third day, I removed the organic matter from the water (which was now beautifully pigmented with tannins) and reduced the liquid by 1/3.
Meanwhile, as the liquid was reducing, I grew the other necessary ingredient for this ink; an iron oxide culture, i.e; rust.
To create this culture, I submerged part of a broken manhole cover I found in Amarillo, TX in a solution of apple cider vinegar and sea salt and allowed this to brew for 48 hours.
To the right is the acorn extraction in the picture above, and to the left is the iron oxide, the middle is the combination of the two solutions. The iron oxide is the catalyst for a chemical reaction within the acorn tannin solution that produces a permanent, non-water soluble purple-black ink.