The red-stained flint crescent from Gesher: new insights into PPNA hafting technology

A red-stained flint crescent found in the Pre-Pottery Neolithic A (ca. 9000 BC) site of Gesher, Israel, provides us with a unique opportunity to study the hafting technology of a particular tool type in the Levant. We present here a reconstruction, based on chemical and mineralogical analyses, of the hafting technologies and materials employed in the process. Use will also be made of relevant studies of the archaeological record. Local material was used for the production of an elastic adhesive paste, mud plaster, which was then hardened to hold the crescent securely in the haft. The study contributes insight into the hafting technology that was most probably implemented in the production and maintenance of composite tools during the Early Neolithic period.     

Multi‐analytical Studies of Archaeological Chinese Earthen Plasters: The Inner Wall of the Longhu Hall (Yuzhen Palace,Ancient Building Complex,Wudang Mountains,China)

The Yuzhen Palace is one of the nine palaces in the Ancient Building Complex built by order of the Yongle Emperor during the Ming dynasty. The buildings were built with dressed black bricks. As a result of the planned national South–North Water Diversion project, the water level in the Danjiangkou Reservoir that surrounds the Yuzhen Palace was expected to rise by approximately 15 m. To avoid submersion of the site, three gates were elevated by 15 m in 2013 and other buildings dismantled, for later reconstruction. The characterization of the construction materials has therefore become of primary importance. Here, we present results on the plasters of the Longhu Hall. The analysis of materials involved a multi‐analytical approach combining optical and electron microscopy with X‐ray and vibrational spectromicroscopies and thermogravimetry. The results indicated the use of two earthen plaster layers and a whitewash finish coating applied over a thin preparatory intermediate layer to improve the adherence of the finish coating to the earthen plaster. Ramie and straw fibres identified in the earthen plasters were added to reduce shrinkage and cracking during drying. The raw materials used and the application technique pointed to a well‐established construction industry using traditional earthen building materials together with lime technology.     

Iron Age hydraulic plaster from Tell es-Safi/Gath,Israel

Hydraulic plasters or mortars prior to the Roman period are rare. Here, we report the identification and characterization of 3000 year old (Iron Age) hydraulic plaster surfaces from the site of Tell es-Safi/Gath. This site, located in central Israel, was occupied almost continuously from prehistoric through modern times, and is identified as the Canaanite and Philistine city of Gath. A survey using an on-site Fourier transform infrared spectrometer (FTIR) identified the presence of amorphous silicates, in addition to calcite, in each of two superimposed plaster layers. This suite of minerals is characteristic of hydraulic plaster. An in-depth characterization of the plasters using FTIR, acid dissolution, X-ray fluorescence (XRF), X-ray powder diffractometry (pXRD), heating experiments and scanning electron microscopy (SEM) coupled with energy dispersive spectroscopy (SEM–EDS), shows that special silicate-containing minerals were brought from some distance to the site in order to produce these plaster surfaces. We therefore conclude that the plasters were deliberately produced, and were not the result of a fortuitous addition of local silicate minerals. A layer of around 150 μm thick enriched in carbonate hydroxylapatite was found in both plaster surfaces, and the same mineral was identified by infrared spectrometry in the surrounding sediments. This suggests that organic materials were used on these surfaces. These surfaces are among the oldest hydraulic plasters known.     

Characterization of archaeological lime mortars in a Ming dynasty tomb: A multi-analytical approach

Lime mortars have played an important role in constructing ancient Chinese masonry structures, including city walls, buildings, and tombs. A tomb built with lime mortars and stones belonging a Ming high-ranking official, Xu Jie, was discovered in Huzhou City of China. Eight different samples from Xu Jie’s tomb, representing four types of lime-mortar-based materials: joint mortar between stone bricks, bedding mortar, grouting mortar, and plaster mortars were collected for analysis and comparison. The characterization of the construction materials has therefore become of primary importance. The function of each mortar was reported and studies into the micro-textural features and mineralogical compositions of those mortars were performed via a multi-analytical approach. The joint mortars were all found to be aerial lime mortars with predominately lime. The bedding mortar was found to consist of lime, soil and sand, typical of a tabia mortar. The grouting mortar was found to consist of lime and ground contact metamorphosed limestone. Analysis of plaster sample taken from the roof of the main tomb identified the presence of calcium stearate/palmitate, indicating the usage of plant-based tung oil as an additive. The analytical results will promote our understanding of Ming architectural technology and craftsmanship, and provide critical information for the conservation of Xu Jie’s tomb.     

Tunnel engineering in the Iron Age: geoarchaeology of the Siloam Tunnel,Jerusalem

The Siloam Tunnel (ST) is the best-identified biblical structure that can be entered today. We use geological, structural, and chemical features of ST and its internal deposits to show that it is an authentic engineering project, without any pre-existing natural conduit that could have guided its excavators. Radiometrically and historically dated to ∼700 BCE, ST pinpoints the technological advance in leveling techniques that was essential for the construction of such a long tunnel without intermediate shafts. A combination of geological and archaeological evidence demonstrates that the circuitous route of ST and the final meeting of the two excavating teams are associated with continuous modifications of the plan to allow acoustic communication between hewers and the surface teams. Hydraulic plaster was applied throughout the tunnel in order to seal voids of dissolution and tectonic origin. Organic material accidentally entrapped in the plaster was carbon 14 dated, and speleothems were dated by U–Th, both corroborating the historic and epigraphic evidence ascribing the engineering advance in tunneling techniques to the Judahite King Hezekiah.     

Painted plaster from Bronze Age Thebes, Boeotia (Greece): a technological study

From the rather difficult excavations that have taken place in Thebes since the beginning of the last century, many fragmentary but often well-preserved paintings on plaster have been unearthed. These belong to several contexts and periods: House of Kadmos (Late Helladic IIIA), Treasury Room (Late Helladic IIIB1) and Oikopedon Spourli (Late Helladic III). Their iconography, style and technology fit well with other paintings from the Late Bronze Age sites found in the vicinity of Thebes (e.g. Gla and Orchomenos). This paper presents a technological study of the Bronze Age painted plaster from Thebes, Greece. The paintings were investigated by means of X-ray diffraction; stereo, reflected light and scanning electron microscopy; some by laser-induced breakdown spectrometry and by micro-Raman spectroscopy, in order to identify the pigments and the composition of the plaster layers, and to determine the painting technique(s) that the artisans may have employed. The plaster layer onto which the paint layer was applied was often the only layer and consisted mainly of calcite, while a clay plaster formed the backing between the lime plaster coat and the actual wall surface. The pigments identified were: yellow ochre, haematite (red), cuprorivaite (Egyptian blue), indigo and possibly riebeckite for blue, charcoal (black), calcite (white), and a combination of black and red for purple. A detailed macroscopic study of the painted surface revealed several features, which indicated that the technique of al fresco painting was employed extensively, a technique already in use since the start of the Late Minoan I phase on Crete. A generally lower level of quality in the appearance of the later paintings (Treasury Room and Oikopedon Spourli) was also noted, but this was not reflected in the materials used or in their overall manipulation.     

Unveiling the Use of Creta in Roman Plasters: Analysis of Clay Wall Paintings From Brixia (Italy)

The paper describes the analysis of a particular kind of plaster from the walls of the Roman Sanctuary (first half of the first century bce ) in the centre of Brixia (now Brescia, Italy), which is an outstanding example of Roman Republican architecture. The walls were plastered and painted with different patterns, imitating marble panels and curtains. Optical microscopy on thin sections, X‐ray diffraction and infrared spectroscopy were performed on several samples of the plaster in order to reveal the execution technique. The palette consisted of glauconite, celadonite, Egyptian blue, and red and yellow ochres. In some cases, an organic compound, possibly a lipidic compound, was present in the external paint layer, as a surface treatment. The plaster contains two superimposed coats: the render coat with lime binder and sandy aggregate; the finish coat with a clay fraction (illite, chlorite, kaolinite), together with calcite from slaked lime and grains of quartz, silicate and carbonate rocks. Although Vitrivius' De architectura reported the use of creta (clay) as daub smeared on reed vaults, the Sanctuary of Brixia represents the first documented use in Roman buildings in a painted plaster laid on a stone masonry wall.     

Petrography of ancient Indian lime plaster

Samples of ancient Indian lime plaster have not previously been analysed. Excavation of a seventh century AD baked brick structure provided the necessary samples for a detailed laboratory examination of plaster. The plaster samples were studied by chemical and petrographic methods. The probable sources of lime and sand were indicated by the mineralogy.     

Salt Effects in Plastered and Unplastered Outdoors Brick Masonry: Quantitative Laser Monitoring of Surface Decay Evolution

In masonry materials, the superficial decay is a widespread problem. Aggressive environmental agents such as moisture and salts trigger the damage by propagating through the material capillary pores. Although several studies have been carried out on salt crystallization and their damaging effects, additional research effort is required to better investigate this phenomenon on real cases and real weathering conditions. To this purpose, testing and monitoring tools capable of following degradation process since the early beginning are necessary. Repeated visual inspections are commonly used to monitor the superficial decay, but this technique is subjective and thus not capable of providing any quantitative information. In this work, an experimental campaign, carried out in Bologna, Italy, is presented. A two-header brick wall, one main face unplastered and one plastered, was stored outdoors and exposed to weathering over two summers. Before the start of the second aging season, moisture and salt capillary rise was simulated by low-concentrated sodium chloride solution (0.1% -wt). The aim was to favor solution evaporation and salt crystallization and to provoke material damage. The degradation process was monitored based on a contactless, rapid and accurate image diagnostic technique. In particular, high-resolution laser scanning by triangulation technique was adopted. Three-dimensional data acquisition was repeated at the end of both seasons. The proposed procedure successfully extracted quantitative information approximately areas of material spalling and detachment even in the initial phases of decay.