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Comparative study of the formation process of oxides in bronze objects according to the microscopic studies
Parastou Naeimi Taraei, Shaiba Khadir,
Volume 1, Issue 1 (Special Issue 1.1 2017)
Abstract
Due to the complex corrosion mechanism of the bronze objects, explaining the structure of different layers of corrosion in these objects at microscopic levels is possible. Typically copper oxide(I) is the first corrosion layer on surface of bronze objects that are excavated of historical sites. However, depending on the environmental conditions، various forms of corrosion layer of tin or copper-rich oxide are formed that are effective in corrosion resistance of objects. Identification of tin oxides or copper-tin corrosion products is not simple by using of routine methods of instrumental analysis.However in this research the formation process of copper and tin oxides of some of historical bronze objects of Iran were studied by using the optical microscope with polarized light that show colored corrosion products and in some cases the method of scanning electron microscopy equipped with elemental analysis (SEM-EDX) was used to complete the identification process of oxide layers. According to the results, identify of evidence of differences in distribution of copper and tin in the microstructure that is result of macroscopic and microscopic segregation, formation of a solid solution of copper besides the copper-copper oxide eutectic mixture during the solidification process, the appearance of copper oxide inclusions in the microstructure of metal, moving The tin-rich layer of copper oxide layer to the outside, formation of copper oxide-tin oxide sandwiching layers, selective dissolution of tin in the outer layers, decuprification phenomenon in corrosion layers  and condensation of tin oxides in the center of sample and finally the usual formation or degradation of copper oxide layer under certain conditions have been studied with microscopic imagesof selected samples of bronze objects which confirmed the ability of microscopic techniques in the study of oxide layers of bronze objects.

A review of the erosion process resulting from chloride attacks in samples of copper and silver-based artifacts
Shaiba Khadir, Parastoo Naeimi Taraei,
Volume 1, Issue 2 (Spesial Issue 1.2 2017)
Abstract
Given the nature of the chloride ion and its tendency to penetrate the inner layers of the metal, paying attention to it in the field of protection of metal artifacts is of great importance. In this article, the effect of the attacking chloride ion on historical copper and silver-based metals has been discussed, and according to the results of a long-term research project on the pathology of metal artifacts in Iran, various examples of artifacts affected by chloride attacks have been briefly presented and compared. In conducting corrosion studies in the aforementioned project, X-ray imaging, optical microscopy, and scanning electron microscopy, and wet and instrumental analysis methods (EDX, XRD, PIXE) were used to analyze the corrosion process. According to the studies conducted, severe pitting corrosion with progressive conditions was observed in the works of the Rasht Museum, as well as corrosion of the tin-rich phase and its simultaneous release as oxide compounds in many of the mirrors in this museum, which in many cases had a starting point under surface sediments when local conditions were provided. This process in the works in museums in southern Iran with high humidity conditions and with chlorides concentrated in the corrosion products has caused the loss of the metal core in many of the works obtained from Hormuz. The concentration and crystallization of chloride in the corrosion layers and the attacks caused by it in the works of the dry regions of Iran, despite periodic humidity or uncontrolled storage conditions after excavation, is the cause of the loss of the metal core of many of the works obtained from Sites such as Sarm, Qoli Darvish, and Sialk have been affected by chloride attacks through different mechanisms, from chloride penetration into the oxide layer to the dissolution and removal of copper from the outer layers. Silver artifacts obtained from different sites have also been affected by chloride attacks, due to the presence of horn silver chloride compounds (Sialk), severe local corrosion (Hormoz), and intermittent copper deposition and the deposition of its chloride salts (Teppeh-e-Hisar).

Technological and Corrosion Studies of BronzeObjects Excavatedin Bam World Heritage Site
Narges Doosti Sani, Mahshid Ilkhani, Shaiba Khadir, Afshin Ebrahimi,
Volume 2, Issue 1 (ویژه نامه 2019)
Abstract
The study of metal works of Bam citadel (Arg-e-Bam) is underway to study the pathology of metalworks in Iran.The aim of this project is to study and investigate the corrosion mechanisms of metal objects. Various metallic works including iron, silver and copper alloys have been gained from the area of Arg-e-Bam. The research is focused on a number of bronze works of this historical site.The studies have been done using Microscopic and Macroscopic methods including metallography, wet chemistry, X-ray diffraction spectroscopy (XRD), scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX). According to dendritic structure of these objects, the results show that most of them have been made in casting method and corrosion products are including Cuprite (Cu2O), Azurite (Cu3(CO3)2(OH)2), Brochantite (Cu4(OH)6SO4), Cassiterite (SnO) and the chloride compounds like Atacamite (Cu2Cl(OH)3), Paratacamite (Cu2Cl(OH)3, Nantokite (CuCl) and Melanothallite (Cu2OCl2). The noticeable point is that there are inclusions containing iron and sulfur in all specimens that represent the using of sulfide ore in copper extraction process.
 
Note: the Challenges of Preserving and Restoring Historical Coins in Private Collections
Shiba Khadir,
Volume 3, Issue 4 (3-2021)
Abstract
Historical coins, as invaluable material documents, not only hold financial significance but also serve as vivid evidence of the history, culture, art, and economy of past civilizations. In Iran, with a rich heritage spanning over 2,500 years, coins play a pivotal role in reconstructing national and cultural identity. However, the preservation and restoration of these historical treasures, particularly in private collections, face numerous challenges. Addressing these challenges requires collaboration and a sense of responsibility among collectors, conservators, and governmental institutions. Raising awareness and providing education on scientific methods of preservation and restoration, along with fostering trust between
conservators and collectors, are essential strategies for safeguarding this valuable heritage. The Ministry of Cultural Heritage, Tourism and Handicrafts (MCTH) and the Research Centre for Conservation- Restoration of Cultural Relics (RCCCR) can play a significant role by offering specialized training and necessary support. Ultimately, historical coins, as an integral part of national and cultural identity, require meticulous and responsible preservation, maintenance, and study to endure as a lasting legacy for future generations.

The Importance of Laboratory Studies in the Process of Research and Cleaning of Historical Coins
Shaiba Khadir,
Volume 6, Issue 1 (6-2023)
Abstract
Identifying the material and the main substrate of a cultural artifact, as well as the surface sediments in the process of conservation and restoration plays a significant role in determining the appropriate methods and ensuring the longevity of the artifact. To achieve this, the use of laboratory-based, instrumental, and microscopic techniques is indispensable. While some experts might be able to recognize the nature of the coin at a glance, this is not always possible, especially when it covered with substantial deposits or when its authenticity is in question.  Therefore, in addition to experimental knowledge and comparative studies, precise laboratory methods are necessary. In the research has been carried out in the workshop of conservation and restoration of metal works of the Research Center for Conservation of Cultural Relies, we encountered instances familiar to many dealing with coin collections. For example, coins with a silver appearance that have become darkened and tarnished due to deposits caused by the surrounding environment and wear and tear, might initially seem to be silver.  However, further investigation often reveals that they are of different alloy or have a Silver coating, or they have been silver-copper coins buried in soil, where deposits and extensive copper corrosion products sometimes make the identification more challenging. Various methods are employed in the study of coins to clarify the economic, social, and political conditions at the time of their minting. Techniques such as PIXE (Particle-Induced X-ray Emission) and XRF (X-ray fluorescence) have attracted more attention from researchers for reasons such as accuracy and non-destructiveness nature. However, it should be considered that in order to obtain a clear and accurate results, the surface of the coin needs to be clean and free of any kind of contamination before conducting these analyses. This underscores the importance of adhering to proper restoration processes for these historical artifacts. Before commencing cleaning, the conservator must consider factors such as the identification of the coin, its surrounding environment or burial and storage conditions, structural aspects, precision in coin minting, and its pathology. Assessment of these factors, not only helps numismatic studies and determining the authenticity of coin, but also assists in selecting the optimal method of cleaning. It should be kept in mind that the inappropriate selection of chemicals or the use of unsuitable mechanical tools can cause serious damage to the artifact's surface and disturb subsequent studies. this research introduces various methods used in the field of study of coins, both hammered and machine-struck, tend highlights the role and importance of laboratory studies in this context.

Conservation and Restoration Operations of the Metal Clogs of the Iran Carpet Museum
Shaiba Khadir, Fathollah Niyazi, Kouorsh Kouhestani,
Volume 6, Issue 4 (3-2024)
Abstract
The "Clogs of the Kaaba" at the Iran Carpet Museum is a pair of metal/ copper alloy shoes by Parviz Tanavoli for an outdoor installation. The work is part of a memorial chapel designed minimalist style within the museum’s grounds. The clogs are crafted to a life-size scale, with their surfaces textured with fine and delicate grooves to enhance their aesthetic and visual appeal. The artist has also applied a dark artistic patina to the surface of the clogs. The interior of the clogs has accumulated dust, soot, and debris from the surrounding greenery. Additionally, prolonged exposure to environmental conditions such as annual rainfall, seasonal temperature variations, and urban pollutants such as acid rain has affected their condition on the ground. The surface of the clogs shows green corrosion products and carbonate deposits. the aim of this operation is to stabilize the clogs and prevent further exposure to harmful urban environmental factors. In order to evaluate and document the current condition, digital photography was conducted on both a macroscopic and microscopic scales. Surface sediment removal was carried out using manual mechanical methods with a scalpel and ultrasonic device. The poultice method was applied in a controlled and limited manner to remove thick sediments using Rachel's salt solution and%2 hydrochloric acid. To protect the surface, a %3 BTA (benzotiazol: C6H5N3) solution was used, followed by a coating of epoxy polyamide solution.

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