Iron Sulfate

Iron Sulfate

Iron sulfate or ferrous sulfate is the catalyst to transform your oak galls into black ink. 

What you have: one rusty nail

What you need: a jar, water, vinegar

Process: put the rusty nail in a jar with a cup of water and a tablespoon of vinegar. 

Wait at least two weeks until the solution becomes dark. Keep covered as the reaction can bubble over and is somewhat corrosive.