Although black inks have been used extensively across time and space to record information, the material investigation of their composition has often remained restricted to specific periods and geographical areas. However, in recent decades scholars in the humanities have shown an increasing interest in the materiality of inks as an inherent part of a physical manuscript. In response to this interest, in their modern editions of ancient texts, papyrologists have often included comments on the writing media used in the original codices, papyri and ostraca (fragments of pottery or limestone used to write on), relying only on visual observation to describe the colour, texture and state of preservation of the ink, along with codicological and bibliological aspects of the manuscripts (e.g. [1, 2]).
Over the last few decades, the Federal Institute for material research (BAM, Berlin), together with the Centre for the Study of Manuscript Cultures (CSMC, University of Hamburg), has embarked on a systematic archaeometric investigation aimed at collecting information on the material composition of black writing media produced before the Late Middle Age (ca. fourteenth/fifteenth century CE). This research has aimed to extend and complement findings from a handful of other material studies, which focused mostly on the composition of black Egyptian inks produced between Pharaonic times and the first centuries of the Common Era [3,4,5,6,7,8,9,10,11,12,13]. One focus of this systematic investigation has been the analysis of inks from Egyptian Coptic manuscripts produced between Late Antiquity and the Middle Ages (ca. fourth–eleventh centuries CE), which started in 2017 as a cooperation with the PAThs Project, based at La Sapienza University of Rome. Other publications resulting from this collaboration can be found in the list of references [14,15,16,17,18]. In parallel to this research, the BAM and CSMC developed further studies on Egyptian inks produced during the Hellenistic and Roman periods (e.g. [19, 20]). The present contribution is a direct output of the research on Coptic manuscripts, and focuses on the material analysis of writing media used towards the end of Late Antiquity (ca. seventh/eighth century CE) in the Monastery of Apa Apollo at Bawit, one of the largest monastic complexes ever to have existed in Egypt.
The monastery of Apa Apollo at Bawit: archaeological and historical contexts
The Monastery of Apa Apollo at Bawit is considered the most important monastery in Egypt in Late Antiquity (sixth–eighth centuries CE). It is located on the left bank of the Nile next to the modern village of Bawit—from which the site takes its name—25 km south of el-Ashmunein, in Middle Egypt, in the ancient nome of the Hermopolites [21, 22, p. 105 n. 1]. Scholars share the opinion that the monastery was founded by a monk named Apollo, who lived in the fourth century CE (Historia Monachorum in Aegypto 8) [2, p. 31–33, 36–41, 23, 24, p. 10–12]. However, so far the oldest archaeological levels excavated have been dated to the late sixth century CE [2, p. 46, 23, 25]. This date is confirmed by the oldest texts from the site [26, p. 133–175]. The monastery remained active into the Islamic Period (tenth–eleventh centuries CE): more recent texts (P.Mich. Copt. 21; P.Bawit Inv. 2003/1-EGN) and some architectural structures [25, p. 185] date from this time.
The archaeological site was discovered in 1900 and excavated first by the French Egyptologist Jean Clédat (1901–1905)  and later by Jean Maspero (1913). After that, the systematic excavation ceased and was restarted only in 2002 [28, 29]. The archaeological works brought to light a large monastic complex with three churches [30, p. 364–365, 31] and buildings from a male and a female community including monastic cells, urban architecture, industrial areas and two necropolises [2, p. 47–54, 25, p. 183–187]. These structures suggest that in Bawit there was a monastic village of considerable size [2, p. 45]. It is estimated that the monastery could have occupied some 40 ha of land . If so, this would be one of the largest monastic sites in Egypt in Late Antiquity and the Early Islamic Period (sixth–eighth centuries CE) [2, p. 55 n. 139, 32]. Literary and documentary texts seem to indicate that it may have hosted some 1000 inhabitants at some time between the seventh and eighth centuries [2, p. 54 n. 136].
The monastery of Apa Apollo seems to have been characterised by a system of self-efficiency. Its economy was very productive, consisting mainly of agriculture, farming and manufacturing activities [2, p. 74–108]. Goods for daily consumption and clothes were produced inside the village, therefore it is likely that writing materials (papyrus paper and/or ink) were also produced locally. Moreover, the monastery and monks also had currency [2, p. 241–259, 33, p. 23–27], meaning that anything the monastery was lacking could have been bought outside.
The papyrological texts from Bawit and those investigated at the Palau-Ribes and Roca-Puig collections
An enormous corpus of manuscripts has emerged from this monastic site. There are more than 700 published papyrological texts [26, p. 133–175], and the digital database Trismegistos has incorporated 1342 documents—including epigraphic texts—from the monastery . The texts are written mostly on papyri and ostraca—pieces of pottery or limestone—in Greek, Coptic and Arabic, since the monastery was active from Byzantine times into the Islamic period. However, most of the manuscripts discovered so far are written in Coptic and can be dated to the seventh/eighth centuries CE.
Most of the known manuscripts from Bawit are documentary texts. The information they provide makes it possible to reconstruct the internal organisation and daily life of the monastery between the late Byzantine and early Islamic period (seventh/eighth centuries CE), when the site probably reached its peak. We have evidence of different types of documents, such as orders to supply goods, payments of salaries, accounts and lists, or even legal texts comprising loans, leases, sales and guarantees. These types of documents often show the use of well-established formulae, and reveal a structured and articulated internal administration [35, p. 104–105], which consisted probably of households hierarchically coordinated by a central institution [2, p. 65–74]. Finally, private relationships and networks are attested by letters. This rich production of documents indicates that the internal organisation system sought to record all the economic activities and business concerning the monastery. Therefore, it is likely that there existed a place, functioning as an archive, where these documents were stored [2, p. 70]. However, some types of documents such as invoices, receipts, accounts, lists or letters may have been kept only for as long as these activities were in effect. This would explain why the verso of existing documents was often reused; papyrus was very commonly recycled in Bawit [2, p. 76, 126, 165–166, 36, p. 10].
So far, the archaeological excavations have uncovered no evidence of a library preserving literary texts or a scriptorium dedicated to their production. However, it is very unlikely that this vast monastic complex was not equipped with such spaces [37, 38], as monastic settlements generally invested a great deal of effort in producing, preserving and transmitting literary religious texts. For the time being, the archaeological excavation at Bawit has brought to light only a few rather small literary fragments. Such is the case of a group of literary fragments, forming part of the same codex, found in 2017 . It is plausible that some literary texts from Bawit were uncovered during illegal excavations and sold on the antiquities market, thus making it challenging to recognise their provenance. This seems to be the case of a miscellaneous codex (P.Cotsen-Princeton 1) whose place of discovery is unknown. Its linguistic features, together with an invocation to “Our Father Apa Apollo” written in the colophon, suggest that this codex may come from the monastery at Bawit [37, 39,40,41].
Historical inks: types and ingredients
Three primary types of ink are known to have been extensively used in historical manuscripts. Carbon ink is a suspension of soot or charcoal particles, derived from a variety of animal or vegetal precursors, in a water-soluble binder. Plant ink is a solution of vegetable extracts obtained after cooking bark, gall nuts or other vegetal matter, producing a mixture of polyphenols. Iron-gall ink has been historically prepared mixing three main ingredients: vitriol (a mixture of metallic sulphates in different proportions, containing mainly iron, copper and, in some cases, zinc ), gall nut extracts, and gum arabic . It is worth pointing out that in the last 20 years, the conservation community has been considering iron-gall ink as a suspension of iron-gallate pigment, obtained from the reaction of bivalent iron from vitriol with gallic acid from gall nuts [44,45,46]. However, a recent study showed that the composition of gall nut extracts is more complex than previously assumed. Depending on the extraction method used, gallic acid can be a minor compound compared to its derivatives (in the form of polygalloyl esters of glucose), suggesting that iron might bind with other polyphenols as well [47,48,49]. Ink mixtures deriving from different combinations of these three primary types of ink, or obtained by adding metallic salts to soot and charcoal, are also documented, and have recently received increasing scientific attention. The difficulties encountered in analytically identifying mixed inks are the subject of a recent article .
Material investigations of historical inks revealed the use of carbon-based inks as far back as the Pharaonic period [4, 7, 13, 51]. A recipe for this type of ink appears in a papyrus with the Book of the Dead (the Yuya papyrus: pKairo CG 51189) , and several recipes are found in the corpus of Papyri Grecae Magicae, dated from the Roman period onwards . Outside of Egypt, carbon ink is mentioned in Vitruvius and Pliny’s treatises [54, p. 290–293, 55, p. 33–34]. By contrast, the material investigation of Egyptian manuscripts has yet to yield any evidence of plant ink. A recipe mentioning this type of ink is recorded in a treatise by Martianus Capella, a Latin prose writer from the fifth century CE [56, p. 225], and other recipes are found in medieval Arabic treatises [57, p. 122–125]. At a certain point in time, iron-gall ink was introduced. To our best knowledge, the earliest recipe of this type of ink is probably reported in a papyrus from the third century CE [58, p. 83]. However, terminological issues regarding the ingredients mentioned hamper the unequivocal interpretation of this text. Material analysis of Egyptian inks has found evidence of iron-gall ink from the fourth century onwards [14, 16, 17]. Therefore, this type of ink was already in use in Egypt during the period of prosperity of the Monastery of Apa Apollo at Bawit, when the manuscripts presented in this study were written.
Mixed inks frequently appear in Arabic recipes. Interestingly, a mixed ink of the type carbon plus iron-gall is described under the name “Egyptian ink” in two copies of the treatise on the arts of the book, Umdat al-kuttāb, by ibn Bādīs (d. 454 AH/1062 CE) [57, n. 101, 59, formula 174]. The original treatise dates from the eighth century CE, being coeval with the manuscripts from Bawit, and is based on earlier sources. However, it was not uncommon for the compiler of a treatise’s copy to change the existing text or add new recipes, thus making it difficult to date them. Furthermore, an ink containing carbon and the copper-based compound chalkanthon (χάλκανθον, whose composition in Antiquity evades identification) is described in the treatise by Dioscorides [60: book 5, p. 114, 183]. Recent archaeometric analyses performed on different collections of Egyptian papyri have revealed inks containing carbon particles and metallic elements (Cu, Fe, Pb) [3,4,5,6, 10, 19, 20, 51]. For the most part, the origin of these metals remains an open question since the metal-containing compounds could not be identified, and their presence in inks could have resulted from several processes. However, synchrotron-based microanalysis recently suggested that lead-based compounds might have been intentionally added as a drying agent to the ink of a corpus of manuscripts from the Roman period . On the other hand, a similar investigation of some Greco-Roman papyrus fragments seems to indicate that copper was present as a by-product in the soot used to prepare the ink . In a different scenario, metallic tools and vessels used during manufacturing, storage and writing may have contaminated the ink. However, scarce information is available on tools explicitly used during these processes. Interestingly, the Morgan Library and Museum preserves a wooden box with a sliding cover and a shallow cavity for a removable metal inkwell dated to the Coptic period [61, p. 601].