Brought to your gracious attention
illustrations for Table Talk 1882 project
(Based on B. Akunin’s book of the same name)

“Black pigment in iron gall ink is a complex of ferric iron ions and polyphenol compounds of natural tanning agents. In Europe ferric iron was mainly derived from iron vitriol (green vitriol, sugar of iron) which is ferrous sulfate that in solution or on paper oxidizes to ferric iron. In Russia they first used iron metal, then a mixture of iron metal and green vitriol and it was not till the end of the 17th century that they preferred iron vitriol. The main source of tanning agents in both Russia and Europe were oak apples (nutgalls). These are bulbous growths formed on the leaves of some oaks in response to attack by parasites. Aleppo (Turkish) galls with the greatest concentration of tannin (60%) were used most often. In Russia where galls collected from native trees contained little tannin (and import was expensive) they also used bark of different trees (alder, oak, fir, larch, ash, etc.) Alder bark was used more frequently as it contained much tanning (up to 16%) and staining agents. To extract gallotannate galls were powdered or crushed and then mixed with soft water (rain, sping and sometimes river water), white wine, strong beer or vinegar. The mixture was either left to ferment for several days or boiled for several hours. Bark required to be boiled for several hours to release the tannins.

Iron metal reacted with tannin water solution to form a low disperse pigment that produced a stroke of deep opaque black similar to that of carbon black ink. This pigment could not yet soak into the fibers and could be easily washed off. It was kept suspended in the liquid by adding gum. To be more durable the ink had to have a high disperse pigment that would sink deep into and bind to the paper fibers. Sometimes, the galls extract was subjected to enzymic hydrolysis which is fermentation with mold in order to release gallotannic acid. A compound of this acid solution with iron metal made indelible ink. Most of the time fermentation was done in presence of organic acids contained in wine, vinegar, sour honey. This was true for both ink derived from iron metal and iron vitriol. One of the European recipes says that “the wine-based ink serves wonderfully the purpose of copying science books, because the letters written in it do not fade and cannot be scrapped off or removed from parchment or paper. But with water-based ink, it is different: the writing can be easily removed, and it can well happen that the letters written in such ink will quickly fade.”

These liquids appear so beneficial for the ink because they contain organic acids such as polyphenols that cause iron ions to form complexes which slows down the processes of formation and aggregation of pigment molecules. As a result, the pigment dispersity rises. A similar effect is produces by other agents contained in bloodwood chips, privet berries, pomegranate peel, Circassian walnut green skin and other extracts that are also added to ink.
It was rather often that copper compounds were used. Copper sulfate was believed to “better bind ink to paper.” These compounds can too form polyphenol complexes which increased the pigment dispersity.

W. Lewis, a British chemist who lived and worked in the 18th century, made an experiment and concluded that the best ink is composed of 1 part of copper sulfate, 3 parts of crushed galls and 1 part of bloodwood chips. In the presence of a large excess of copper sulfate (he took equal parts of sulfate and galls) the ink faded from exposure to light within several days. The ink made in the presence of an excess of galls (6 times the quantity of sulfate) was paler, but more durable.”