The evolution of strength,elasticity and rupture behaviour of birch tar made with ‘double-pot’ techniques during tar cooking

Birch tar was the first adhesive produced by humans. Its study has consequences for our understanding of human evolution and the development of specialised craftsmanship. One of the better-documented birch tar making methods is the ‘double-pot’ technique, where two containers are used, one containing bark, the other collecting the tar. Birch tar made with double-pots has low viscosity and bad adhesive properties. To obtain a usable adhesive, it must be reduced in volume by cooking. We investigate the evolution of tar’s mechanical properties during cooking. We use lap-shear tests to investigate strength, stiffness and failure behaviour. We found that tar must be cooked for 90 min to acquire adhesive properties. When cooked for longer, strength and stiffness increase over a 30 min lasting time span. Cooking for even longer, beyond this 30 min window, produced a substance that could no longer be used as an adhesive. The implications are that tar cooking requires a high level of skill because specific signs indicating the desired properties must be recognised during the process. Tar cooking constitutes a supplementary investment in time and resources and appears to be associated with a certain degree of risk.     

Mortars in context: An integrated study of mortars and plasters from the so-called Ginnasio in Solunto (Sicily,Italy)

This paper presents a multipronged scientific study of mortars and plasters of the so-called Ginnasio in the Hellenistic–Roman city of Solunto (Sicily, Italy). A selection of 16 well-contextualized samples was collected to represent different functions and building phases of this private house. The results show that a variety of locally available raw materials was used as aggregates and to produce binders. The diversity of raw materials’ sources and production techniques identified in this study reveals the advanced technological knowledge of the builders of Solunto, indicating a complex relationship between the settlement's cityscape and its surrounding landscape.     

The reconciliation trap: disputing genocide and the land issue in postwar Guatemala

ABSTRACT

Guatemala’s reconciliation debate is as much about the present and the future as it is about history. In order to highlight its political dimension, I propose to read this controversy through the lens of hegemony theory. It is precisely because of the entwinement of specific political economic interests, centuries-old ethnic conflict and structural racism in Guatemala that charging genocide constitutes a key moment in a fight over power—a fight in which controversies about the politics of history are also expressions of struggle over economic resources and political hegemony. In this light, reconciliation does not appear to be a solution but a trap, set by those who defend their interests against the changes that the Peace Accords and the recommendations of the Historical Clarification Commission demanded. In the first section, I show that one crucial motive for these elites to deny the Guatemalan genocide, besides obvious reasons of historical shame and responsibility, is economic issues, among them the century-old land question. In the following sections I present two seemingly contrary arguments from the political and academic left. One takes apart, from a poststructural perspective, simplifying binary logics of class and ethnic conflict and thus delegitimizes the indigenous and peasant struggle for economic reform in the process. The other proposes a form of universal guilt that also ends up depoliticizing the history of the civil war.     

Ceremonial objects or household items? Non‐destructive μ‐XRD2 and μ‐XRF studies on three Neolithic hematite axes from Qatar

Three small stone axes were collected by the joint Qatari‐German South Qatar Survey Project (SQSP) at two places close to the eastern and western coast of Qatar in autumn 2012. Associated with settlement remains, flint artefacts and pieces of ?Ubaid pottery, the implements have been dated to the fifth millennium BCE. Non‐destructive μ‐XRD² and μ‐XRF analyses could, for the first time, prove the use of hematite as the raw material for the manufacture of these tools in Arabia. The absence of major hematite sources in the region and the special characteristics of hematite — a unique metallic shine of polished pieces and the blood‐red colour that appears during the manufacturing process — suggest the highly symbolic character of these objects.     

A multi-analytical approach to characterize an Early Bronze Age cosmetic material from Müslümantepe,Southeastern Anatolia

The present paper reports the chemical and mineralogical composition of a black pigment material contained in a Syrian Bottle-shaped vessel excavated on an Early Bronze Age grave in Müslümantepe, a site located at the right bank of the Tigris River in Southeastern Anatolia. A combination of different analytical tools like state-of-the-art non-destructive μ-XRD², μ-XRF and μ-Raman spectroscopy compared to classical powder XRD was used to characterize the content of the bottle. The results attest the presence of a manganese mineral (pyrolusite) most probably used for cosmetic purposes. This is the first evidence, which is scientifically tested, of the earliest use of cosmetics in the Upper Tigris of Southeastern Anatolia during the Early Bronze Age period, c. 2700–2550 bc.