Journal of Research on Archaeometry
Year:2016 | Volume:1 | Issue:2 |Papers Count:6

Investigation of gypsum-based historical materials has two main problems: philological problems and technical issues. Technical issues, the main topic of this article, are normally consequences of physicochemical complexity of gypsum crystals in different conditions and variety of additives or mixed materials. Neglecting this technical problem, leads researchers to misunderstand or misinterpret these materials. Moreover, exclusively use of one analytical method, such as scanning electron microscope or X-ray fluorescence, provides an incomplete picture of samples that regularly produces further misunderstanding of specimen or its history. The methodology of this study is a multianalytical approach via XRD, SEM and using image analysis software on electron photomicrographs to estimate amount of free spaces in microstructure of samples. A group of three experimental samples were made from traditional recipes of craftsmen in Iran, in order to make a connection between philological problems came from tradition, and technical problems came from mineralogical property of gypsum. Gach-e Tiz, or quick setting mortar shows a very dense microstructure in SEM micrographs. Variety sizes of monoclinic crystals of gypsum are present in it, and moreover some shapeless and bulky regions are also visible. Gach-e Kam-Mayeh, or low setting mortar reveals a much more open microstructure than the former one, filled with needle like crystals and a lot of micro porosity between crystals. There is no evidence of bulky forms area in Gach-e Kam-Mayeh. Gach-e Koshteh, or mechanical low-setting mortar which is a traditional Iranian recipe, shows a parallel layers of laminar gypsum crystals setting upon each other. This form also demonstrates no evidence of bulky regions. Historical samples were collected from a stucco decoration belong to Kuh-e Khwaja ofSistan; a gypsum mortar fragment from Shadyakh, Neyshabur and a piece of gypsum mortar from Alamut castle of Qazvin. The results of XRD show that both layers of Kuh-e Khwaja stucco contain anhydrite as the major phase and the sample of Shadiyakh mostly composed of Gypsum. Organic materials extractions represent no evidence of organic additive to this historical materials. Therefore the images of their microstructure are comparable with experimental samples that made without any additive. Lower layer of Kuh-e Khwaja’s stucco shows a lot of tiny crystals that are not very look like gypsum, but precipitated on the surface of bigger and deformed crystals. The microstructure of it is very open and include big amount of micro porosity in compare with other samples. Upper layer of this stucco shows not any form of gypsum crystals but very disturbed flaked shapes, supposedly gypsum crystals transformed to anhydrate. The micrographs of Shadiyakh’s mortar also reveal not any clear form of gypsum crystals but base on XRD result it still as gypsum materials. This sample contains mostly from that bulky and dense structure which shows the usage of low amount of water for its paste. The results of image analysis on electron micrographs at magnification of ×250 and ×500 provide a good and comparable estimation for free space evaluation in the micro structure of gypsum based materials. The combination of these techniques and methods lead to better understanding of gypsum based historical materials.

Organic materials, due to their vulnerable structure, are considered as rare archeological materials.Therefore, the number of research and literature about these materials is limited. In this project, four leather artifacts found in Chehrabad Salt Mine of Zanjan belonging to Achaemenid period have been studied in three sections: first, identifying the type of animal whose skin has been used in producing these artifacts; second, identifying the tanning materials; and third, identifying the materials used in fat liquor processing. For identifying the animal species, cross section of leather samples were studied using optical microscopy method. Results showed that sample no.1 is of cow skin, sample no.2 of goat, and sample no.3 and 4 are of sheep skin. These results can prove the hypotheses related to animal species. For identifying tanning material, presence of plant tanning agents was studied using ferric chemical test. The results revealed the absence of any tanning agents and this disproves the hypotheses related to tanning material. For studying the existence of mineral tanning material, SEMEDS elemental analysis technique was used and the results showed the absence of those mineral material; concluding that no tanning material used in the samples. For identifying the materials used in lubricating process, GC-MS technique was used. Separating organic compounds in samples, this technique also proved the absence of vegetable tanning materials in the process of manufacturing these artifacts and this confirmed the results of ferric chemical test. Comparing the compounds identified by GC with MS library, some fatty acids were recognized. Linoleic acid and stearic acid were identified in sample 1 which shows the presence of sunflower oil. Oleic acid and capric acid (decanoic acid) were identified in sample 2, but no material could be found with these two fatty acids. Probably two materials have been used in lubricating process of this sample. In sample no.3, only oleic acid was found. For sample 4, no fatty acid could be found, proving the absence of oil and fat in this artifact. Finally for ensuring the results of GC-MS, FT-IR technique was used. In this regard, two important absorbance bands of fatty acids i.e. O-H and C=O bonds were considered. All samples, except sample no.4, showed absorption in mentioned areas. Thus FT-IR confirmed the result of GCMS analysis. These results support the hypotheses given about the materials used in lubricating process of the samples.

The enamel painting has a long history in Iran. However, this is a lost art and few glass artists are interested in enameling. The oldest traces of Zarrin Faam performed on glass containers were found in Egypt in the second century AH. Since then, this technique was used on glazed pottery at the Islamic era. Zarrin Faam, a thin layer of copper and silver nanoparticles, is an enamel in which luster glaze is used in painting and decorating on the glaze which is heated in reduced kiln as the third step. There are two historical literature about technology and composition of luster glazes: “Araes al-jawher wa nafaes al-ata eb ” (by Abul Ghasem Kashani), and “ Jawaher-nama-ye Nezami ”. But the only book that explains art of enameling on glass is the second one by “Mohammad Ibn al Barakat Neishabouri” written in 595 AH. The author has indicated the formulas for crystal enameling. In this research, two formulas of this book has been explained and, it was tried to adopt an experimental approach to introduce and recognize the art of lusterware enamel. Afterwards, technique of glass Meenakari or enameling was practiced. The chemical composition of this layer was investigated using scanning optical microscope, and the results suggested that vitreous Zarrin Faam enamel can be made in accordance with the formulas mentioned in the book, and under reduction conditions. It was found that type of glass, Mina compound or formula, and reduction condition are among the factors influencing the formation of lusterware layers. It is noteworthy that reduction firing includes several variables such as firing time, temperature, and fumigation intensity.It could be concluded that making lusterware at the proper way can be achieved by choosing the appropriate factors mentioned.

In this paper the bituminous water proof mortar, which has been used between the bricks in the Achaemenes monument of Tall-e-Ajori in Persepolis, has been analyzed by different instrumental chemical analysis methods, such as Fourier transform infrared spectroscopy (FTIR), X ray diffraction (XRD and X ray florescence spectroscopies (XRF). Moreover, due to identifying the chemical structure and explanation the degradation processes during thousand years of remaining in burial environment, the classical extraction by organic solvents and optical microscopy studies were also done. According to classical extraction test results, the physical state of the bituminous water proof mortar is a duple mixture that include organic and inorganic parts, where the characteristic of the material is actually a natural asphalt. The organic part of this bituminous mixture was analyzed by FT-IR method for identifying the main organic functional groups such as alkanes and aromatic molecules, XRD analysis determined the presence of inorganic phases such as Calcite, Anhydrite, Feldespar (Ca), Quartz and Dolomite, and the result of XRF analysis determined weight percent of CaO, SO3, SiO2, Al2O3, Fe2O3 and MgO. The degradation processes during thousands of years in the burial environment have developed the age-hardening reactions which decrease the saturated molecules concentration such as oils and resins in bituminous mixture, and caused the enhanced fragility and brittleness in the structure of the material. So, the results obtained clarifies the importance of conservation programming and climate controlling for optimum preserving of the bituminous mixture mortars in the Achaemenes monument remains of Tall-e-Ajori in persepolis.

This paper is based on a research on the problems of salt attack and rising damp in heritage masonry buildings. Amongst common building defects occurrences in heritage buildings, salt attack and rising damp are considered as the most challenging, particularly in building conservation. Rising damp and salt attack, a worldwide phenomenon, are major causes of decay to masonry materials.Moisture and salts in masonry walls can result in damage. The presence of water-soluble salts in porous building materials is one of the principal problems of conservation. Salt attack and rising damp together pose a serious threat to buildings especially with regard to load-bearing walls constructed of brick, stone and mortar. The problem of salt attack is closely associated with rising damp. On its own, rising damp can make buildings unsightly and unpleasant to occupy. The situation is made much worse if there are appreciable quantities of soluble salts present, because the rising damp will carry salts up into the masonry to where the damp evaporates. Moisture from the rising damp makes the salts existing in the building material soluble, or the ground water which contains salts finds its ways through the building wall. Salt damp is caused when moisture from the ground is carried up into the wall of a building. This process involves the movement of water from a high concentration, being the ground, to a low concentration, being the porous wall, which is called capillary action. Rising damp occurs as a result of capillary suction of moisture from the ground into porous masonry building materials such as stone, brick, earth and mortar. They may cause unsightly deterioration of building exteriors and interiors as well as possible building structure failures if left untreated. Their crystallization is in fact the cause of those phenomena of deterioration that so often appear on surfaces: lack of cohesion, scaling, flaking and bulging. When the water transporting the salts through porous materials evaporates, due, for example, to changing climatic conditions, the solution becomes more concentrated. As soon as it becomes supersaturated, the salts crystallize giving rise to both efflorescences on the surface and/or sub-efflorescence’s below the surface layer. The impact of salt damp is often worse on external wall surfaces, especially those exposed to direct sunlight, where evaporation is higher. This moisture then evaporates on or just below the wall surface leaving the salt residues behind. There the salts are left behind and can often be seen as a white efflorescence on the wall surface. When these salts grow as crystals within the pores of the masonry they can disrupt even the strongest material, leading to fretting and crumbling of the surface. These formations gradually contribute to building dilapidation and reduce the building aesthetic values. The telltale signs of salt attack in a wall are: fretting mortar or stone or brick, bubbling paint, crumbling plaster, and the presence of moisture on the surface of the wall. It is very important to know the salt content of deteriorated surfaces both to understand the causes of decay and plan conservation strategies. The nature of the salt provides us with informationabout its origin and therefore, indicates the possible conservation treatment to adopt. Sources of salts can be the building materials themselves (sand, bricks, mortar), or external sources (soil, materials used for conservation treatment, pollutants in the atmosphere, sea spray, de-icing salts scattered on roads in winter, and products generated by the metabolism of micro- organisms). The results of this research showed that almost all masonry contains soluble salts, principally sulphates, nitrates, chlorides and carbonates of sodium, potassium, calcium, magnesium and ammonium and so, all liquid water present in walls is more or less a diluted salt solution. Sources of these salts may be natural or human induced. But, not all salts generate decay. This depends on their solubility, hygroscopicity, mobility and the hydration level of their crystalline form.

In the last decade, increasing and develop of the scientific discipline such as science, engineering and medicine was considerable. With respect to this point of view, nowadays, comparative and interdisciplinary disciplines are also collaborated to each other. Archaeological investigations followed by related scientific methods would try to get answer to the problems which were mentioned by archaeologists due to the know-how in antiquity. Archaeometry means, the use of new instrumental, statistical methods for interpreting the technology based on collected archaeological data. In another word, archaeometry is a methodology for data management which has been collected via different expertise of each scientific discipline. Archaeometrical studies focus mostly on generate and development of common language for linking human science with another discipline such as science, engineering and medicine.