iron gall ink

Ingredients

lab-grade tannic acid, ferrous sulfate heptahydrate, distilled water, gum arabic, copper (II) sulfate pentahydrate, zinc (II) sulfate heptahydrate, aluminum sulfate hexadecahydrate, chromium (III) potassium sulfate dodecahydrate

Preparation Steps

Original Recipe Text

Iron gall ink was prepared by mixing 0.787 g of gum arabic in 9.2 mL of distilled water. The solution was made five times. Lab-grade tannic acid (1.23 g) was dissolved in 25 mL of distilled water. A ratio of 5.5 moles of iron to 1 mole of tannin was chosen. A mole fraction of 0.7 moles of metal salt to 1 mole of iron was used. Each of the five metal salts and gum arabic solutions were slowly added to each tannic acid solution while the water was stirred constantly to avoid clumping (p. 65). The inks were then stored in screw-capped vials in a dark room (p. 66).

Evidence

"Five laboratory iron gall inks were created, each made from of a different metal sulfate. Each of the five inks consisted of the following ingredients: lab grade tannic acid, ferrous sulfate heptahydrate, water, and gum arabic."

Remarks

The experiment compared lab-grade tannic acid inks to those made from Aleppo galls. Aleppo gall-based inks were found to be superior in fluidity and legibility, exhibiting a purple-black color and desired uniformity (p. 60). Lab-grade tannic acid inks showed lack of fluidity and precipitates (p. 60). The study concluded that as ink ages, the tanno-gallate iron complex separates and precipitates out of solution, decreasing legibility (p. 61).