The origins of black ink go back to at least the third millennium BC if we believe some sources. However, some scholars believe that its origin may be even older by a thousand years and that it was already in use in India during the fourth millennium BC. For sure, the Egyptians knew and used it around twenty five hundred BC and there are papyri from that time that still show an intense black color in spite of their old age. The main component of these primitive inks was soot or smoke black, and later, vegetable or animal substances carbonized and then ground. Maybe you have noticed that some black paint today is sold under the denomination of ivory black and maybe you have found it curious because, after all, ivory is almost white. The denomination actually goes many centuries back, and comes from the fact that carbonized ivory was very appreciated as a black pigment. Then, the black was mixed with some agglutinating agent that could be glycide-based such as honey, lipid-based such as oil, or protein-based such as egg white, yolk, or animal glue. But the most appreciated agglutinating agent was gum Arabic. This substance is extracted from the tree called acacia Senegal or acacia verek, but some fruit trees produce substances that could serve the same purpose. Different color hues or even a pleasant aroma could be conferred to the mixture by adding some other component. This type of ink is still used and sold under the name of Indian ink or carbon-based ink. During the middle ages, as now, it was found in tablets that were dissolved in water to produce the writing ink. Carbon ink has the advantage of being chemically inert and that means that it is not subject to either oxidation or reduction. And, therefore, the color won't degrade at all nor will the ink affect the support. Understanding that nothing in this world can be perfect, carbon inks have the inconvenience that they don't penetrate the fibers of the writing support and can very easily be washed off especially on the glossy flesh side of parchment and therefore, Western Europe preferred another sort of ink known as metalloacid ink, or rather ferrogallic ink, iron gall ink, ochoa ink, or just common ink. The main ingredients of this sort of ink are vegetal tannins contained in the so-called gull nut, some sort of metallic salt that is normally iron sulphate and an agglutinating agent. Let's study them one by one. The gull nut is a vegetal the trees of the oak family form on their bark as reaction to the bite of certain insects that deposit fertilized eggs at the bite site. There are many types of gull nuts and the most appreciated ones are naturally those with a higher tannin concentration, such as the Aleppo nuts. When gull nuts were not available, one could resort to other natural products with similar properties such as the marobalonus family, carobins, acorns or even the bark of certain trees and bushes. Once harvested, the gull nuts or substitutive products were crushed and let to soak in the water, beer, or wine to extract the tannins. The hydrolysis of it produces gallic acid, glycides, and phenol. The other main ingredient for the gull nut ink is iron sulphate also known as vitriol, chalchantum, atramentum, or shoemaker's black. Some recipes also mention copper sulphate, but we know that copper sulphate won't produce the desired reaction and if it worked, it was because they are impurities contained in the copper. During the middle ages, the best part of the European vitriol came from the mines of Goslar in Germany. There, the fluid that ran through the mine's wells was collected in iron pockets and left there to rest. Sometimes in order to increase their own contents, iron fillings was added. Vitriol was also obtained as a side product of the alum manufacture. When the gallic acid is mixed with the iron sulphate, a reaction happens and the result of it is a black precipitate that is a ferrogallic complex that acquires a blue hue when oxidized. One of the components of this black precipitate is sulfuric acid. As the amount of sulfuric acid increases, so increases the intensity of the black color. The problem is that as the amount of sulfuric acid increases, the ink becomes more corrosive. The presence of impurities in the iron sulphate will cause a change of hue in the ink in the direction of orange, blue, or green. The last ingredient for the iron gall is gum Arabic. It's high viscosity helps to homogenize the precipitate but increases the ink acidity. Under the most appreciated gum Arabic was extracted from the acacia senegal that grows in the areas of semi-desert sub-Saharan Africa as well as in Oman, Pakistan, and Northwest of India. In Europe some sort of substitutes could be found such as plumtree gum, egg whites, and even honey. Europe knew of iron gall ink from fairly early times around the third century AD but its use became widespread only from the 11th or 12th century. Iron gall ink has the advantage of easily penetrating the fibers of the parchment, but has the inconvenience of a high degree of acidity that makes it corrosive for the writing support. Especially when it is used on paper, it can even disintegrate it. As a matter of fact, then use of acid inks in combination with paper is the main enemy of the western written heritage. Together with two types of ink that we have just seen, the medieval world also knew the so-called mixed inks, which were essentially carbon inks with some tannic derivatives added, or maybe metallic salts, and the incomplete inks, which received that name because they lacked some of the useful ingredients. We also know about totalization of bizarre substances such as the sepia ink mentioned by Aulus Persius and Plinius in the first century AD. According to the French scholar, Monique de Pas, vegetal ink was predominantly used in Niger and the near east, while Europe made use of mostly iron gall ink. In the Middle East and Africa, we find a mixed type together with the other two main types.
