Regardless of the information they contain, manuscripts, which are books, papers, and documents, are tangible cultural heritage objects and reflect their era [1, 2]. The most important problem in the conservation and transfer to future generations of cultural heritage materials such as the book, paper, and leather in which the manuscripts are found, is that they are deteriorated and damaged from the moment they are produced [3]. The paper, which is mostly used as a support material in manuscripts, has a cellulosic structure that is easily found in nature and has been a long-term carrier and keeper of information. It undergoes degradation by chemical, physical and mechanical effects [4]. Deterioration is any chemical and/or physical change in the state of an object. Physical and chemical degradation are interrelated and often occur simultaneously [5, 6]. There are many reasons for damage to manuscripts. These are production methods and techniques, materials such as ink, pigment, and dye [3, 7], storage and exhibition conditions, environmental factors, people, misgovernment, etc. [8]. Mismanagement, misuse, and carelessness are obstacles to the long-term preservation of cultural heritage collections [9]. Unfavorable environmental conditions are the leading factors that cause deterioration: temperature and relative humidity [3, 8, 10], light [5–10], air pollutants and biological pests such as microorganisms, insects, molds, and fungi [10]. In cases where the relative humidity is high, acid hydrolysis reactions occur and the pH value decreases accordingly. This causes the paper to become brittle. In addition, in paper or parchment manuscripts with iron-gall inks, iron ions can move to areas where there is no ink, creating additional areas for oxidation. High-temperature fluctuations and humidity cause both ink and paper to deteriorate. In addition, it causes deterioration of the vellum by causing the ink layer to flake and disappear [11]. The main reason for the deterioration of materials such as paper and books is the breakdown of the cellulosic structure due to chemical attacks due to acidic hydrolysis, oxidative agents, light, and air pollution, the biological attack caused by the presence of microorganisms such as bacteria and fungi [3, 12, 13]. The reactions between inks and carrier materials (paper, vellum, etc.) are strongly influenced by environmental factors, especially temperature, and relative humidity, and by size and inorganic fillers [12].
One of the materials used in manuscripts is ink, and the oldest inks are carbon-based. These materials are easily obtained soot/smoke, brand, coal obtained from other plant sources, and graphite obtained from nature [14]. The calligraphers in the Ottoman Empire, mostly used lamp-black or burnt linseed oil, resin, or tar-based ink pigments to prepare carbon-based black ink [15]. Later, black inks obtained from ivory and bone were used. In addition to these inks used, iron-gall inks used by the Late Roman Empire in the west until the 19th century and even the 20th century were the primary choices for the creation of many manuscripts [14, 16–20]. It is known that the expression gallotannate, which indicates iron-gall ink, was used in Pliny's book in the 1st century AD [14, 16, 21].
In the period between the 3rd century BC and the 5th century AD, there are various writing inks in black colored, which can be grouped into different types. These are pure soot or charcoal-based inks, copper or lead-added soot inks, soot and iron-gall inks or mixed inks containing tannins, and additionally pure iron-gall inks [19]. Iron-gall inks have been used throughout history as the standard writing and drawing ink, as they are more difficult to remove from the applied surface and easier to produce than carbon-based inks [20]. It has been described in the use of official records and personal letters, in diaries, map drawings [11], some paintings by artists such as Rembrandt, Guercino, and Lorrain [22], and in musical notes (J. S. Bach and Victor Hugo) [14, 16, 22–25]. These ink components contain corrosive transition metal ions and acids that have been shown to cause severe damage to the paper carrier. The use of iron-gall ink gradually declined in the 19th century due to the development of various synthetic inks [4, 18, 26, 27].
Another material seen in manuscripts is pigment, and the palette used in early manuscripts, Egyptian papyri, was limited. The ockr pigments, mostly obtained from iron-based soil, colored the manuscripts. After iron-based soil pigments, pigments such as Egyptian blue, Egyptian green, and cobalt blue were used in manuscripts [14]. Aceto et al. studied two Byzantine (VIth century) manuscripts in the Austrian National Library in Vienna and achieved some results. According to analyses results, they dedected that ultramarine, azurite, red lead, orpiment, red and yellow ochers, and blue and yellow colorants known as vergaut were used to give green tones [28].
Another material used as a colorant in manuscripts is dyes. Unlike pigments, dyes are organic and derived from plants, insects, fungi, etc. are obtained from structures in nature. The use of natural dyes has been documented in ancient times, and many natural substances have been used as dyestuffs for centuries in various parts of the world [29]. The natural dyes and colorants are an important part of cultural heritage, the colors used have been common to all civilizations [30]. Organic natural dyes used in illumination and other manuscript decorations were applied in an aqueous solution for dyeing paper either directly or due to the use of mordant dyes. While the first semi-synthetic dyestuffs have been on the market since the last quarter of the 18th century [31], fully synthetic dyestuffs were introduced to the market in the second half of the 19th century. Until this date, dye sources of vegetable or animal origin have been used for dyeing [30, 31]. When looking at synthetic dyes, basic, acidic, or direct dyes are preferred for dyeing cellulosic paper [31]. Archival materials such as paper and books are a multi-component system containing cellulose, fillers, size, and colorants. Since the natural color of the paper, dirty white, was not liked much in Islamic geography, the manuscripts were primarily applied on colored papers [4]. The dyes can generally be characterized if a sample can be obtained for chromatographic analysis [32]. While this is usually done for textile objects containing loose threads, in principle this can be extended to manuscripts [14]. Although there are not many studies on the analysis of dyes in manuscripts, one of the studies conducted in this area revealed that the weld plant was used to color the last papers in a 15th century manuscript in Egypt [33]. In another study, the dyes in Moroccan manuscripts were examined. According to the analysis results, safflower dye was detected on orange-colored papers, while Safranine T, a basic dyestuff, a mixture of mono azo dyes (Ponceau RR, Fast Red AV, Crocein Orange, and Orange II) or a combination of both were determined in fuchsia-colored papers [31]. Aceto et al., on the other hand, identified indigo, madder, and Tyrian purple in dyes in two manuscripts in the Austrian National Library in Vienna [28]. Melo et al. identified Brazilwood pigment lakes and orcein purple colors in three illuminated parchment manuscripts dated to the 13th, 15th, and 16th centuries [34]. Hidalgo et al. investigated the iron-gall ink in medieval Iberian manuscripts using high-performance liquid chromatography-electrospray ionization-mass spectroscopy (HPLC-ESI-MS). Researchers have determined that the concentration of gallic acid in the writing ink varies depending on the extraction method and the ink recipe [26].
The most commonly used leathers for bookbinding are obtained from calf, sheep, and goat skins [6]. Most of the leathers used in bookbinding have been tanned leather of vegetable origin since prehistoric times [35]. Tannins obtained from plants have been used for centuries in tanning peltry and leather, making the material less perishable and more waterproof [36]. At the same time, vegetable-tanned leather has been used in the production of a wide variety of objects such as book bindings, shoes, garments, saddlery, furniture upholstery, liquid containers and ornaments, as well as a support material for decorative and artistic products [37]. The main sources of chemical degradation of leather material are UV light and air pollutants mainly SOx and NOx. Özellikle karbon ve nitrojen arasındaki kovalent bağların kırılması ile derinin kollajen yapısında oksidasyon oluşabilmektedir [38].
Iron-gall inks are composed of four main components: tannin, vitriol (iron or copper sulfate), water, and gum arabic [11, 17, 18, 22, 26, 39]. Of these materials, vitriol is referred to as copperas, sal martis, vitriolum commune, vitriolum romanorum and vitriolum cyprinum in some recipe books. Vitriol was called chalcantum (blood of copper) by the Greeks in ancient times, and attramentum ("black" or "making black") by the Romans. The word attramentum was used both for its salt property and for the color it produces when combined with tannin. Vitriol has been obtained from various mines by different techniques. Therefore, ferrous sulfate can be found in the ink solution with varying proportions of many other metals such as copper, aluminum, zinc, and manganese that do not contribute to color formation [22]. The purpose of using gum arabic is to act as a binder in the dispersion of the ink in water [40].
Iron-gall inks show the infrared signature of gallotannins. This indicates that Fe3+ polygalloyl ester complexes of glucose are formed [26].
Throughout history, the quality of iron-gall inks has varied greatly depending on the quality and proportions of the ingredients. At the same time, different additives also played a large role in these changes. Examples are the use of acids to slow settling, humectants such as glycerine to slow drying, and materials such as alcohol to inhibit mold growth and prevent freezing [11].
A common aspect of tannin dyes is that color fastness, light and washing fastness are very good, that is, color fading is not too much. This is a disadvantage in most cases. This disadvantage is that some gray and black colors obtained with iron mordant deteriorate over time and the color turns brown and gradually erodes the fibers to which it is attached by being fixed. Therefore, most scientists study the aging caused by iron-gall inks and dyes to preserve historical fabrics and written documents [36]. The degradation mechanism caused by the combination of a tannin substance and an iron compound was compared with the degradation caused by iron-gall ink on paper. the degradation is caused by hydrolysis from oxygen in the air catalyzed by acidic compounds and free iron ions [18, 19, 22, 40, 41]. In ink production, a complex is formed by combining tannic acid and ferrous sulfate compound (FeSO4) before it is applied to the paper, and then the resulting black ink is applied to the paper or parchment [11, 19, 22, 41]. After the ink dries on one of these supports, it slowly oxidizes to form a complex water-insoluble pigment that darkens from purple-gray to black [11, 22]. Iron tannate and sulfuric acid (H2SO4) are formed from the combination of ferrous sulfate compound and tannic acid. Also, an excess of free tannic acid and ferrous sulfate is released [41]. This is called ink corrosion [11]. Although all these obtained components are effective in the deterioration of the paper, the main reason is the released H2SO4. Iron tannate can decompose into tannic acid and iron ions during degradation, which can cause hydrolysis and oxidation. The biggest reason for the deterioration of iron tannate is due to unfavorable storage conditions [41]. Iron-gall inks have a low pH due to the acidity formed by the main components iron(II) sulfate and tannic/gallic acid [18, 24, 27]. Acid-catalyzed hydrolysis, which causes low pH, causes the bonds in cellulosic paper to break (decrease in the degree of polymerization) and thus the loss of fiber strength [4, 42, 43]. Components such as vinegar and urine added to change some of the ink's properties can also affect the pH of the ink. For example, the pH of a paper containing iron-gall ink can vary significantly from 2.9 to 7.1. A low pH value causes the degradation of cellulose, which is the main structural component of paper [18, 27].
Ink corrosion causes undesirable effects on paper or parchment. These include a gradual change of ink color from black to brown, discoloration, and loss of strength in paper or parchment, embrittlement, cracking or loss of fragments in ink-filled areas, and deterioration of other adjacent/close materials over time [11, 22]. In general, the accepted paper protection approach for the conservation of iron-gall ink corrosion is the so-called "calcium-phytate treatment method". In this method, paper artifacts with iron-gall ink are immersed in an aqueous suspension containing antioxidant phytate and calcium hydrogen carbonate solution [18, 44, 45].
The work of scientists and the analytical methods and techniques they use in the preservation of cultural heritage is extremely important in the decision-making process regarding the conservation approach [15]. Numerous analytical methods and techniques have been developed over several decades. Thanks to these methods and techniques, material characterization of paper, leather, ink, pigment, and dyes, production methods and techniques, and deterioration products can be detected [3, 15]. It has been possible to obtain additional information about its social, economic, technological, and cultural context through material characterization and determination of production methods and techniques [25]. At the same time, the analytical methods used are extremely important and necessary in terms of identifying materials and determining the causes of deterioration, as well as elucidating interactions between different materials, and providing dating and/or authentication [15]. The best studied example for dating is the work of Goler et al. [46].
Espina et al. studied to determine the characterization of iron-gall inks in certain manuscripts using various spectroscopic techniques such as Raman, Fourier-transformed infrared (FTIR), UV-Vis absorption, and fluorescence spectroscopy [17]. Haskovic and Ibragic used XRF and FTIR techniques for the detection of inks and pigments in manuscripts [15]. Darzi et al., on the other hand, used SEM-EDX and µ-Raman techniques to investigate the widespread use of colorants, raw materials, and color production technology in the Qur'an manuscripts of the Qaajar period (1789–1925 AD), Iran. As a result of their study, they determined inorganic origin carbon black, Prussian blue, ultramarine, vermilion, and red lead pigments as colorants. In the organic structure, they determined the anthraquinone structure in a red-colored sample. In the yellow color of another sample, they determined compounds containing saffron and lead, which are thought to be used as an agent and/or chemical drier. They also detected brass, pure gold, and gold-silver alloy as gilding ink/dye [1]. Melo et al., on the other hand, used micro spectrofluorimetry and surface-enhanced Raman spectroscopy (SERS) techniques to detect organic colorants in medieval manuscripts [47].
A wide variety of analytical methods and techniques are used to identify the elemental compositions of iron-gall inks, and the X-ray fluorescence (XRF) technique has become the preferred analysis. Specifically, the development and use of the fingerprint model based on the quantitative and semi-quantitative determination of inorganic components such as iron, as the main component of iron-gall inks, is another element that allows their reliable classification. Iron-gall ink is not homogeneous when examined with a microscope, although it has a dark crystalline structure. It gradually loses its opacity in the near-infrared region. When examined by Raman spectroscopy, they show a characteristic spectrum at 1400 nm. In the paper, the iron-gall ink penetrates the substrate but shows preferential penetration around the parchment [19].
It is extremely important to use non-invasive, non-destructive methods and techniques to provide material characterization and other information without sampling from manuscripts [48]. Sometimes samples are separated from the main structure due to the natural aging and/or deterioration of such artifacts, and this is often referred to as self-sampling [14, 49]. Sometimes this object may owe itself to minimal sampling due to its existing bad state. Sometimes a deliberate choice may be made to take a small sample to obtain valuable information that would otherwise be inaccessible [50].
Turkish Manuscripts And Their Characteristics
The process initiated by the Turks within the framework of conservation dates back to the 15th century before the first museums were established. Some cultural heritage objects, which were considered movable and valuable in the Ottoman period, were kept in a more suitable place to protect and coexist. During the reign of Mehmed the Conqueror (1451–1481), valuable materials such as weapons and caftans were conserved in this way. Some of these weapons, which have been conserved from the past to the present, constitute some of the collections of the Istanbul Military Museum, and textile objects constitute the large textile collection of the Topkapı Palace Museum [51].
Although it is not known when the first manuscripts appeared, according to the available data, it is known that the oldest manuscript dates from the 4th dynasty in Egypt, about 4600 years ago [14]. There is information that the use of iron-gall ink was used in the Middle East in the 5th century AD [19]. Martianus Capella, who lived in Carthage in the 5th century, describes iron-gall ink in the "Seven Free Arts Encyclopedias" [22].
Since printing activities started to be used widely in the 19th century in the Ottoman Empire, paper and books were produced by making individual manuscripts before this date [51]. The earliest examples of Islamic binding art date from the Tulinid period, 865–905 AD, and have been found in Egypt and Tunisia. The oldest known Turkish manuscript belongs to the Uighurs, the last of the pre-Islamic Turkish civilizations, and is dated to the 7th century AD. The oldest volume, in which the original features of the Ottoman bindings can be seen, belongs to the middle of the 15th century, and the most striking examples were produced in the 15th and 16th centuries. It is known that the Ottoman manuscript and bookbinding style developed in the cities of Edirne, Istanbul, Diyarbakir, and Bursa [52]. In addition to calligraphers, Ottoman sultans contributed significantly to the production of manuscripts during the Ottoman Period. In addition to writing poems and texts, they attached great importance to the development of manuscript collections by illustrating books with miniatures [53].
The papers used for manuscripts in the Ottoman Period have different properties. These may vary in physical properties such as thickness, hardness, and color, as well as being domestic or foreign [51]. The first paper to Anatolia corresponds to the date of the establishment of the Turkish states in 1071, and the paper was imported first from the east and then from the west. Doğu'dan ithal edilen kağıtlar Şam, Semerkant, Tebriz (İran), Bağdat, Türkistan, Hindistan ve Çin'den; batıdan ithal edilen kağıtlar İtalya (Venedik), İngiltere, Fransa, Almanya ve Hollanda'dan geliyordu [52]. İthal edilen kağıtların en popüleri Semerkand'dan (bugünkü Özbekistan) gelen kağıtlardır ve bu kağıtlara "Semerkandî" adı verilmektedir. Paper mills were established in the Kagithane district of Istanbul in the 15th century, in Yalova in the 18th century, and in the Hamidiye district of Istanbul in the 19th century during the Ottoman period, and domestic paper production was carried out [51].
The preservation of the papers and books that make up the manuscripts in the Ottoman Empire began in the care of voluntary copyists and later collectors. Sometimes these objects were collected together to form the libraries of various foundations. There are many libraries established like this in Istanbul, Turkey. These libraries transferred the administration of their collections to the larger institutions that were created later. The collections transferred in this way were donated to the Süleymaniye Library at the beginning of the 20th century, and these works are still saved and conserved today [51, 54]. As of the beginning of 2023, all the objects in the Süleymaniye Library were moved to the "Rami Library", which was previously used as a barracks and was later restored. The objects are preserved, restoration and conservation processes are carried out and some artifacts are exhibited in the Rami Library at the moment. There are manuscripts in many categories such as history, geography, literature, medicine, astronomy, logic, music, and Islamic sciences in the collection, which was previously in the Süleymaniye Library and later moved to the Rami Library [55]. Apart from the manuscript collection in the Rami Library, there are 17 more main libraries in Turkey where manuscripts belonging to the Ottoman Period are preserved and restoration and conservation works are carried out [56].
Historical Background
Held at the Manuscripts Library of the Rami Library in Istanbul, the Animal Encyclopedia is the first book about animals written in the Ottoman Empire. The 62 volumes collection was written from 1487 until the death of the author in 1501. Handwritten, the books are leather bound and decorated with colorful illustrations, and are regarded as a very valuable manuscript collection.