I see a lot of people recreating iron gall inks lately. There are many sellers on Etsy. It seems unwise to resurrect a corrosive ink that has eaten away so many manuscripts.

Walnut husk ink is a gorgeous and easy alternative. I get mine at S.F. Herbs by the pound, soak for at least a day or ferment in distilled water, and boil down until it's as dark as I like. Some borax or sodium benzoate can keep the surface from molding.