4 Material und Umwelt
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- 4 Material und Umwelt (440)
- 4.4 Thermochemische Reststoffbehandlung und Wertstoffrückgewinnung (93)
- 4.1 Biologische Materialschädigung und Referenzorganismen (91)
- 4.3 Schadstofftransfer und Umwelttechnologien (81)
- 4.2 Material-Mikrobiom Wechselwirkungen (77)
- 4.5 Kunst- und Kulturgutanalyse (66)
- 4.0 Abteilungsleitung und andere (46)
- 6 Materialchemie (30)
- 1 Analytische Chemie; Referenzmaterialien (27)
- 6.1 Oberflächen- und Dünnschichtanalyse (16)
An existing pyrometallurgical process for tantalum and niobium recovery, mainly from low grade pyrometallurgical residues, was investigated. Series of melting experiments were carried out in a pilot-scale electric arc furnace to study how the amount, the grain size and the way of feeding affect the activity of carbon as a reducing agent. During the pyrometallurgical treatment refractory metals such as tantalum and niobium are reduced to their carbide form and enriched in the molten iron-based metal phase. The cooled down slag and metal phase were analysed to investigate thermodynamic and kinetic conditions of the carbide formation. FACT Sage simulations were also used to investigate the material system in state of thermodynamic equilibrium. Results show that mass transfer and kinetics may play an important role if compared to equilibrium analyses using FACT Sage.
The use of secondary building materials can meet the requirements of sustainability in several ways: the extended time availability of primary raw materials and, thereby, the protection of natural ressources as well as the conservation of landfill sites. Regarding the predicted decrease of gypsum supply in Germany, particularly the recycling of gypsum (calcium sulfate) is of growing importance. Currently, the gypsum demand is fulfilled (at least 60%) by gypsum as side product from coal-fired power plants (FGD Gypsum). Germany’s natural gypsum deposits fulfil the remaining gypsum demand. Due to national climate protection goals the gypsum supply from coal power plants will decrease significantly in the future.
In addition, the content of sulfates in other secondary building materials, in particular in recycled concrete aggregates, should be minimized for quality reasons. Separated gypsum can be used in gypsum production if the high quality requirements for recycled gypsum are met. Accordingly, there have been significant advancements in the processing of gypsum residues in the last years. Since almost all processing steps in the recycling process are associated with environmental impacts, an evironmental evaluation of the use of recycled gypsum as a substitute in gypsum production has to be carefully conducted.
The presentation focusses on the techniques for generating recycled gypsum from gypsum plaster boards, the related quality requirements and a comprehensive environmental evaluation of the complete process.
The lecture traces the origins of paper, the manufacture and the spread from China to the Middle East and Europe.
Though technological progress considerably affected each step of the manufacture of paper, the essence of the invention remains unchanged until today. The process of manufacturing handmade paper can be divided into a number of steps:
- choosing the raw material (e.g. cellulose from wood, cotton, rags)
- beating and grinding the fibres into small pieces
- producing a liquid pulp of the desired texture
- treating the pulp with various additives
- filling the pulp suspension into a paper mould
- draining the water
- pressing and drying to get the actual sheet
- various post-production treatments
We will see how the manufacturing process is reflected in the properties of the paper and its degradation. A special attention will be paid to the instrumental analysis for identification of the paper types. Also watermark play an important role in the studies of the manuscripts. A short overview will be offered at the ends of the lecture.
Inks and pigments
(2019)
The writing materials used in various cultures and epochs can be divided into two groups. The first comprises materials that write themselves, producing script by rubbing their own material off onto the writing surface. It includes charcoal, graphite, chalk, raddle, and metal styluses. Depending on the material and consistency, these are cut or pressed to make styluses and then used for writing.
The second group comprises all coloring liquids that are applied to the writing surface with a quill, pen, or printing block. It includes inks made from dye solutions (for example, tannin inks) and those made from pigment dispersions (for example, sepia, soot, and bister inks). The latter are sometimes also rubbed as pastes into letters incised into the writing surface, where they increase visual contrast.
Due to the variety of recipes and the natural origin of raw materials, there is a wide range of different components and impurities in writing materials.
Soluble inks (Tinten)
Soluble inks are based mainly on dyes forming a water solution. Colored inks were manufactured with different plant or insect dyes (e.g. Brazil wood, kermes). To stabilize the volatile material, the dyes were mixed with a mordant (e.g., alum).
Brown plant inks – best-known as blackthorn or Theophilus’ inks – are usually produced from the blackthorn bark and wine. In the early European Middle Ages, inks of this kind were widely used in the production of manuscripts in monasteries. Usually, they are light brown, so sometimes small amounts of iron sulfate were added, which led to what was called an “imperfect” iron gall ink. The difference between “classic” iron gall ink and such imperfect ink is therefore not clear: the distinction is not possible, especially with the naked eye.
Dispersion inks (Tuschen)
According to its generic recipe, one of the oldest black writing materials is produced by mixing soot with a binder dissolved in a small amount of water. Thus, along with soot, binders such as gum arabic (ancient Egypt) or animal glue (China) are among the main components of soot inks. From Pliny’s detailed account of the manufacture of various soot-based inks, we learn that, despite its seeming simplicity, producing pure soot of high quality was not an easy task in Antiquity. Therefore, we expect to find various detectable additives that might be indicative of the time and place of production. One such carbon ink requires the addition of copper sulfate . The experimental discovery of this ink in 1990 led to a misleading expression “metal ink” that is sometimes found in the literature.
Colored dispersion inks based on pigments such as orpiment, cinnabar, or azurite have been known since Antiquity. Natural or artificially produced minerals are finely ground and dispersed in a binding medium. As in soot inks, water-soluble binders such as gum arabic or egg white were used.
Iron gall ink (Eisengallustinten)
Iron gall inks are a borderline case between these two groups. They are produced from four basic ingredients: galls, vitriol as the main source of iron, gum arabic as a binding media, and an aqueous medium such as wine, beer, or vinegar. By mixing gallic acid with iron sulfate, a water-soluble ferrous gallate complex is formed; this product belongs to the type “soluble inks”. Due to its solubility, the ink penetrates the writing support’s surface, making it difficult to erase. Exposure to oxygen leads to the formation of insoluble black ferric gallate pigment, i.e., “dispersion ink”.
Natural vitriol consists of a varying mixture of metal sulfates. Since for ink making it was obtained from different mines and by various techniques, inks contain many other metals, like copper, aluminum, zinc, and manganese, in addition to the iron sulfate. These metals do not contribute to color formation in the ink solution, but possibly change the chemical properties of the inks.
Parchment
(2019)
This lecture will present history of parchment based on written sources and chemical examination of antique, medieval and modern parchment.
Our studies of the Dead Sea Scrolls writing surfaces show that they can be divided roughly into three groups: leather, parchments of a light tint, and those of various shades of brown. The latter ones are invariably tanned, whereas the middle group is characterized by the presence of various inorganic salts. Some of the pale parchments, among them the Temple Scroll (11Q19), are remarkably similar to medieval European parchment. Therefore we have formulated the working theory that in the Judaea of the Hellenistic period two different parchment-making traditions existed side by side: an ‘eastern’ one (represented by the tanned parchments of Qumran, closely resembling Aramaic documents from the fifth century BC, and a ‘western’ one (represented by the untanned/lightly tanned ones similar to early Christian Greek parchments).
This division has found support during our studies of the Geniza fragments, in which Babylonian and Palestinian traditions seem to follow the “eastern” and “western” technologies, respectively.
Natural sciences play auxiliary role in the studies of manuscripts. The success of their contribution depends strongly on the formulation of the question and the choice of the methods to obtain the requested answer. Therefore, one should try to go beyond the understanding of the basic principles of the scientific analysis.
We will start with a glance at the basic principles of the techniques used in the material science for determination of the elemental composition (X-ray emission) and molecular composition (FTIR & Raman). We will move then to the bench and mobile equipment commonly used in the field of cultural heritage. At the end we will choose a question to be answered and design an ideal experiment that will be modified according to the limitations dictated by on-site conditions.
In the ateliers in the afternoon we will
a) compare two XRF devices that differ in their spatial resolution;
b) use a high resolution microscope (Keyence) to obtain a close look at writing surfaces and materials;
c) we will learn to determine the type of the inks with the help of another microscope (DinoLite AD413T-12V), a usb microscope with visible, UV and NIR illumination;
d) we will learn to use FTIR-ATR device for determination of the type of the writing surface;
e) We will use mobile Raman device for identification of pigments.
The evolution and socio-geographic distribution of writing inks from Late Antiquity to the Middle Ages are one of the foci of our investigative work at the Bundesanstalt für Materialforschung und -prüfung (BAM) in Berlin and the Centre for the Study of Manuscript Cultures, Hamburg University.
This presentation will examine the inks used by Jews in the in different geographical zones try to correlate the results of the material analysis with written records and existing traditions. We will compare the inks proposed by Maimonides, who lived in 12th-century Egypt, with the considerations of Rashi, who lived in 11th-century northern France, and see that they both advocated use of the inks commonly known and produced in their respective regions. It is Maimonides who proposes to add tannins to the soot inks, but rejects the metallic salt, both of which were practices that were well attested in contemporary Arabic recipes for making ink. In contrast, Rashi was favourable to employing the plant inks in use in contemporary Northern Europe.
While studying the socio-geographic history of inks, division 4.5 of the Bundesanstalt für Materialforschung und Prüfung (BAM) together with the Centre for the Study of Manuscript Cultures (CSMC) in Hamburg has developed a non-invasive protocol for ink analysis. It consists of a primary reflectographic screening to determine the type of the ink (soot, tannin or iron-gall) and a subsequent in-depth analysis using several spectroscopic techniques: X-ray fluorescence (XRF), Infrared and Raman spectroscopies. The first of them, XRF elemental analysis aims at establishing the unique fingerprints of inks containing metals or trace elements in carbon inks. In addition, we use Raman analysis to identify so-called mixed inks, an ink category that received little attention so far. Finally, with the help of IR spectroscopy we obtain information about the ink binders.
Our research aims primarily at recreating a socio-geographic history of inks, parchment, and papyrus and includes the comparative analysis of the writing materials of the Dead Sea Scrolls, ink and papyrus in Ancient and Hellenistic Egypt, and inks in documents from various contemporary medieval communities in Fustat (first nucleus of Cairo) as well as other medieval Jewish and Armenian communities.
The presentation shows the panorama of historic inks and our attempt to follow up the transition of the inks from those based on soot to the iron-gall inks commonly used in the Middle Age.