Abstract
Stucco art in Islamic period, in terms of technique and decorative motifs, pattern is taken from decorative art of Sassanids period. Motifs of stuccoes Sassanids period with inspiration from nature, does communicate (communication doesn’t exactly, but close to it), and can be easily identified similar samples it. This shows that unrealistic patterns less used in these motifs, and artist has shown less tendency to this direction. But these elements under the influence Islamic wisdom, have changed their form and meaning. One of the important findings and indicator in Aveh site were decorations stucc, that during the excavation in Imamzadeh Fazl Ibn Soleyman, obtained in the third chapter excavations this historic site in 2009. According to the date mentioned on one of the luster tiles found from this building (684  A.H.), this decoration is belongs to Ilkhanids period. The authors seeking to prove such dating, have done shape and technique used in this motifs and compare them to other historic sites stucco decorations from Ilkhanids period. This research has done to study this question related with Imamzadeh Fazl Ibn Soleyman building that, basically, this building based on stucco decorations, related with which period? And, stuccoes related to which style? In this regard, the present study seeks to prove these assumptions in execution of decoration motifs of stuccoes this building, has been used two styles stucco decorations with high bulge and decoration motifs caved. The decoration motifs are contains foliate, geometric, and inscribed. These motifs and their styles have been modeled from Ilkhanids styles. The method of doing this research is descriptive – analytical – comparative. Data in this study are taken from Library resources and field work. Field works in this study are contains extensive excavations in Aveh plain and in Imamzadeh Fazl Ibn Soleyman. Furthermore, cultural material obtained from excavation, have been drawn.
Keywords: Ilkhanids, Stucco decorations, Decorative motifs, Imamzadeh Fazl Ibn Soleyman of Aveh.

Introduction
The decoration of buildings Islamic period of Iran, usually have been used from brick, plaster, and tile. From of stucco, from early Islamic period to Timurids period as there has been template element in the decoration, and it has been most used in prayer niches and inscriptions of buildings (Pope, 1987: 166). Stucco at first has been more used for cover the rugged surfaces and decorate them; but, in the fifth century  A.H., stucco has been transformed from a simple decorative mode to unique coating of decorative. Traditionally, stucco art has been among of decorative art dependent on architectural of Iran, that after from flourishing in the Sassanid period in middle centuries of Islamic and in Ilkhanids period has reached the peak of flourishing.  In fact, Ilkhanid period is golden age of stucco in Islamic period Iran. This art in Ilkhanid period in vast areas as a decorative element in architecture of this period has used. From this period are remained traces very beautiful and unique. 24 km from Saveh County to Salafchegan is separate road to Qom; this is road of Jafarabad – Qom. The village of Aveh is located about a 6 km from this road. (Hashemi, 2007: 125). Imamzadeh Fazl Ibn Soleyman in Aveh plain, based on obtained indications from field works of authors (discover the luster tile in this building with date 684  A.H.), is one of the architecture monuments in Ilkhanid period with decorations of tile-making and stucco. Stucco decorations this building, although a small number is obtained, but they are represents the pinnacle of stucco art Ilkhanid in middle centuries of Islamic. The main purpose of authors in this study, in first place, have been presented available sample from stucco art Ilkhanids from Aveh area; In second place, have been analysis of their decorative motifs (technique), and type of motifs used (foliate, geometric, and inscription), and comparison them with other similar samples in other historical places.

Stuccoes of Imamzadeh Fazl Ibn Soleyman Aveh
After reviews on these stuccoes, their technique was studied in two groups: stucco decorations with high bulge, and decoration motifs caved. Techniques of shaping stucco decorations are with high bulge to form of in situ, mold, or combined from both techniques. In technique decoration motifs caved, has used from both techniques in situ, and mold. Furthermore, decoration motifs of stuccoes this building has been studied in tree group foliate, geometric, and inscribed. The foliate motifs of stuccoes is to form of arabesque and cinquefoil motifs (high and stretched), and Rosette flower. The most of foliate samples obtained in decorations of stuccoes Imamzadeh Fazl Ibn Soleyman Aveh, are from of type of foliate motifs six and eight of fimbria, flowers and leaves (several of fimbria) with buds, and arabesque motifs.The geometric motifs used in stuccoes of Imamzadeh Fazl Ibn Soleyman building are most to form of the honeycomb motifs. 
In stuccoes of Imamzadeh Fazl Ibn Soleyman building has been seen inscribed. Unfortunately, inscriptions used in decorations this building, aren’t in good position for recognize the type of script and decorative style. Authors have been results based on speculation and also based on lines used in decoration of tiles luster painted this building (that from of types of Sols and Naskh script).

Conclusion
As was mentioned, decorative motifs of stuccoes in Imamzadeh Fazl Ibn Soleyman building are divided to foliate, geometric, and inscribed, and they have been created to two styles: stucco decorations with high bulge, and decoration motifs caved. With comparison decorative motifs this building with decorations other traces in Ilkhanids period Iran, could be seen significantly specifications of decorative style of Ilkhanids in this building. So, decoration motifs Imamzadeh Fazl Ibn Soleyman building are related to Ilkhanids period. Therefore, date mentioned on the tiles this building and decoration motifs of stuccoes have been contemporaneous. On the other hand, comparison of shaping stuccoes Imamzadeh Fazl Ibn Soleyman with contemporaneous buildings, power of architects Islamic in Ilkhanids period is show.

 Abstract
During the Safavid period, innovations were created in Stucco decorations. the Koshtehbori Stucco decoration is one of the most attractive and unique architectural decorations of the Safavid period, which was implemented with various motifs in some of the buildings of that period and has a special creativity and innovation that is different from the implementation of other types of Stucco decorations. Knowing the methods and implementation steps of Stucco decorations in restoration projects and studying them is considered as one of the essential elements and an inseparable part of the protection of historical Stucco decorations. The purpose of this research is to identify the similarities and differences, the variety of methods and the stages of implementation of Koshtehbori Stucco decoration with other Stucco decorations in the architecture of the Safavid period. The questions of this research are: What are the similarities and differences of Koshtehbori Stucco decoration with other Stucco decorations in Safavid period architecture in terms of the method and stages of construction and execution? What is the appropriate classification for technical types of Stucco decorations in Safavid architecture? The research method is descriptive-analytical and comparative, and the collection of findings is in the form of library studies and field observations. The results of the studies showed that, unlike other Stucco decorations of the Safavid period, in the execution of the Koshtehbori Stucco decoration, Finishing, polishing, Convex or concavity was not done on the surface of the motifs, and only the background of the design or some carving motifs. In terms of the method, stages and sequence of execution, the Koshtehbori Stucco decoration, is the most similar to the Stucco decoration with carved colored layers. These similarities are in terms of the thickness of each layer of one millimeter and the method of cutting at an angle of 90 degrees to the surface of the motifs and polishing and smoothing the carved parts. Is. Also, in terms of the method, steps and sequence of execution, the Koshtehbori Stucco decoration, is the most different from the carved decoration filled with colored gypsum.
Keywords: Koshtehbori, The Technique of Implementing Stucco Decorations, Classification of Stucco Decorations, Safavid Period Architecture.

Introduction
Stucco decorations in Iran’s architecture have been implemented with different techniques and methods, one of which is the Koshtehbori Stucco decoration. The method and technique of execution of the Koshtehbori Stucco decoration in the Safavid period architecture is different from the Stucco decorations before it and required less time and economic cost per unit area than the relief Stucco decorations of the previous periods. This ornament has a special beauty, it has a variety of colors or different motifs. Previous research by experts in Iranian architecture and art history has focused mostly on Stucco decoration motifs and less on stucco types, comparative analysis of construction methods and techniques. A special classification and understanding of the execution method of Safavid period Stucco decorations can draw more attention to documentation and practical aspects in their basic maintenance and restoration. This research aims to identify the similarities and differences, variety of methods and stages, and execution order of the Koshtehbori Stucco decoration in comparison with other Stucco decorations of the Safavid period, as well as classify the Stucco decorations of this period.
The research questions are: What is the appropriate classification for technical implementation types of Stucco decorations of Safavid period architecture? What are the similarities and differences between the Koshtehbori Stucco decoration and other Stucco decorations of the Safavid period in terms of construction methods and stages? Research method: This research used a descriptive-analytical method to investigate some architectural Stucco decorations in Iran through library studies and field observations. The statistical population of this research includes 6 types of common Stucco decorations in Safavid architecture. The common features and differences between the Koshtehbori decoration and other Stucco decorations of the Safavid period were presented in a descriptive-analytical and adaptive-comparative method in terms of execution methods and stages. For this purpose, common Stucco decorations were examined in terms of the order of executive layers, such as support, scratch coat(arriccio) and fine coat (intonaco) layers, type of background, design drawing and stabilization, plastered layer, and finishing steps. The findings of this research were collected through written and documented sources, as well as field investigations by the authors, including pictures of examples of common Stucco decorations of the Safavid period architecture. In addition to proposing a new classification and naming of some decorations, the research analyzed different types of Stucco decorations by comparing samples to identify similarities and differences between Safavid period Stucco decorations.
 
Discussion
- Presenting a suitable classification of Stucco decoration of Safavid period architecture
This research proposes a new classification system for Stucco decorations in Safavid period architecture based on seven specific criteria. These criteria include the method of shaping, the kind of materials used in the background, the appearance of the surfaces on the motifs, the size and amount of relief, finishing works, in terms of the background and shape of the motifs. Each criterion has a different category, which allows for a more precise identification and recognition of different Stucco decorations. This classification system is crucial for the conservation and restoration of these decorations, as it helps to avoid unprincipled interferences in restoration interventions.
 
- A comparative study of the Stucco decoration of Koshtehbori with other Stucco decorations in Safavid period architecture
In this regard, six different Stucco decorations that were commonly used and innovative during the Safavid period were selected and compared with the Stucco decoration of Koshtehbori in terms of execution method and order. These are:
A: Stucco decoration of Koshtehbori: This decoration, with different techniques and motifs, has been implemented in some buildings of the Safavid period. These decoration are often prepared, designed and implemented with various geometrical, Khataei and Slimy motifs on a background of plaster mortar, which is different from other plaster ornament methods.
B: Stucco decoration with carved colored layers: Among other Stucco decorations in the architecture of the Safavid period, this decoration is the most similar to the Stucco decoration of Koshtehbori.
C: Stucco decoration on Simgel: This decoration is different from the Stucco decoration of Koshtehbori in terms of grouting with mud in the background (empty space between the motifs), the curvature around the motifs, the relief of the motifs, and the shape of the motifs.
D: Stucco decoration on a flat mirror: In this Stucco decoration, flat mirrors are used as a Stucco substrate. In terms of the mirror background between the patterns, the curvature around the patterns, the relief of the patterns, and the shape of the patterns, this Stucco is different from the Stucco decoration of Koshtehbori.
E: Stucco decoration on the Koj mirror (Kopbori): This Stucco decoration is made using the combination of Koj mirror and Stucco parts. This decoration, in an additional stage of initial drawing and transfer of the design, adhesive plaster mortar behind the mirror, in terms of the mirror background of Koj between the motifs, the curvature around the motifs, the relief of the motifs and in the shape of the motifs with the Stucco decoration of Koshtehbori is different.
F: The Naghri Stucco decoration filled with colored gypsum mortar: the Koshtehbori Stucco decoration is the most different from the carved Stucco decoration filled with colored gypsum mortar compared to other Stucco decorations in Safavid period architecture
In the end, the six Stucco decorations of the Safavid period are compared with their sub-groups in the seven classifications in the architecture of the Safavid period. Based on this comparison, we can observe their similarities and differences in the subgroups. For example, the shaping technique of the six types is done in situ, and the type of material used in the background of the Koshtehbori Stucco decoration, the Stucco decoration with carved colored layers, and the Naghri decoration filled with colored plaster is gypsum. However, in the other three decorations with different materials, it is Simgel, flat mirror, and koj mirror.

Conclusion
Through the study and research conducted, a more comprehensive classification and suitable division for Stucco decorations in Iranian architecture has been presented. In this research, Safavid period gypsum decorations are classified based on a specific seven criterion, which includes shaping technique, material used in the background, surface appearance of patterns, size and amount of relief, and complementary works, in terms of both background and pattern shape. Each of these criteria has its own subgroups. 
Stucco decorations in Safavid architecture have similarities and differences in terms of their technical aspects and design. In the execution of the Koshtehbori Stucco decoration, unlike other Safavid Stucco decorations, carving, polishing, convex or concaving on the surface of patterns was not performed, and only the background or some parts of the pattern were carved and polished. In terms of the method, stages and sequence of execution, the Koshtehbori Stucco decoration, is the most similar to the Stucco decoration with carved colored layers. These similarities are in terms of the thickness of each layer of one millimeter and the method of cutting at an angle of 90 degrees to the surface of the motifs and polishing and smoothing the carved parts. Is. Also, in terms of the method, steps and sequence of execution, the Koshtehbori Stucco decoration, is the most different from the carved decoration filled with colored gypsum. Stucco decorations on Simgel, on flat mirrors, on Koj mirrors, in terms of the surface of the motifs, which may be Koj or a combination of Koj and Kav, and also, the type and appearance of the motifs, are different from the Koshtehbori Stucco decoration.

Abstract
Zahhak Castle in Hashtrood, one of the prominent archaeological sites in northwestern Iran (East Azerbaijan Province), houses valuable stucco decorations. A portion of the artifacts recovered from excavations is preserved at the Zahhak Castle site museum, another portion in the storage of the Azerbaijan Museum in Tabriz, and a limited number in the museum’s main gallery. These artifacts include animal, human, floral, and geometric motifs. The present study aimed to evaluate the crystalline structure, mineralogical composition, and the extent of structural degradation of the excavated stucco decorations, employing laboratory techniques including X-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM), ion chromatography (IC), proximity, and monitoring of environmental conditions (temperature and humidity). To compare structural damage, samples from both the site museum and storage artifacts were selected and analyzed. Phase analysis results indicate that the main phases of the stucco decorations are gypsum (CaSO₄·2H₂O) and quartz (SiO₂), with minor amounts of calcite (CaCO₃), albite (NaAlSi₃O₈), anorthoclase (O₈(Si₃Al)(Na,K)), and anorthite (CaAl₂Si₂O₈) also identified. According to IC results, the presence of harmful chloride and nitrate ions was detected at low and non-destructive levels. Crystallographic data suggest that structural alterations mainly occurred prior to excavation and during artifact burial. However, the high humidity conditions at the site museum and the lack of adequate conservation standards may accelerate deterioration processes. For optimal preservation, it is recommended that environmental temperature and humidity be continuously monitored and that standard display cases, along with periodic monitoring, be employed as effective conservation measures.
Keywords: Qaleh Zahhak Hashtrud, Stucco Decorations, XRD, Fe-SEM, Heritage Conservation.

Introduction
Excavations at the Zahhak Castle site in Hashtrood were conducted on a limited scale by Ghandgar and Rahmatpour between 2000 and 2007. During the excavations in the hall of the site (which is now the Zahhak Castle site-museum), a number of stucco decorations with various motifs—including plant, human, animal, and geometric designs, as well as pieces related to half-columns—were discovered. The stucco decorations obtained from the Zahhak Castle excavations are currently preserved in two collections: The Azerbaijan Museum in Tabriz and the Hashtrood Museum. These decorations include 47 pieces housed in the Azerbaijan Museum and a considerable number of stucco fragments of various sizes that remain at the site-museum. Of the 47 stucco pieces in the Azerbaijan Museum, five are displayed in the main galleries, while the remaining pieces are kept in the museum storage under relatively stable temperature and humidity conditions. The stucco works at the Zahhak Castle site are currently placed on the ground on a plastic sheet covered with excavation soil, and some pieces are kept in glass display cases and niches within the site-museum.
Considering the thermodynamic properties and crystal solubility of gypsum, along with the specific temperature and humidity conditions at Zahhak Castle during different seasons, it is not unexpected that these conditions may lead to particular changes in the structure of the excavated stucco decorations. This study aims to investigate these changes by comparing the microstructure of the stucco decorations at the Zahhak Castle site with those housed in the Azerbaijan Museum. The research examines these changes by analyzing the environmental parameters to which the pieces have been exposed, as well as considering the chemical composition of the gypsum used in the decorations and the ions present in the site environment. The processes that have caused—or may cause—the deterioration of these works will be evaluated. Ultimately, the study seeks to propose appropriate environmental conditions that would lead to the more sustainable preservation of these artifacts.
Therefore, the research questions are as follows: What types of damage have affected the stucco decorations at Zahhak Castle, and what are the causes of this damage? Additionally, what temperature and humidity conditions are most suitable for the proper preservation of the stucco decorations at the site?

Discussion
Site-museums encompass historical sites that have been excavated during various archaeological seasons. The primary purpose of creating such spaces is to present important archaeological findings and data derived from excavations. During excavations, some artifacts are preserved in situ by providing necessary conditions and facilities, and are made accessible to the public so that visitors can establish a direct connection with the context of the artifacts’ creation and formation.
In site-museums, visitors can simultaneously observe both the artifacts and the historical site, while also witnessing ongoing archaeological activities as well as conservation and restoration operations (Hassanzadeh, 2012: 378). The quality of the museum’s interior space is enhanced through the arrangement, organization, and structuring of its elements and forms, and it is designed with the aim of creating an attractive environment for tourists (Azarbouye Dinki et al., 2018).
Accordingly, the display cases at the Zahhak Castle site-museum (Fig. 1) are not suitable for the proper preservation of the stucco artifacts under study. These display cases should not only ensure protective security but also enable better exhibition of the artifacts. Currently, the artifacts are kept in glass display cases that allow visitors to access the items by sliding the glass and, in some instances, even remove them from the cases.
The overall arrangement of visual elements is designed to prepare the viewer’s mind to receive information. The artifacts inside the display cases are arranged in two rows, and visitors must sit to view the items on the lower level, which sometimes discourages them from observing these pieces. Additionally, the artifacts are presented without any information regarding their condition, year of discovery, or function, which generally renders them meaningless and of little cognitive value to visitors.
For designing an appropriate enclosure for the Zahhak Castle artifacts, it is recommended to consider the display case and communication spaces, the visual requirements of the environment, climatic conditions, lighting, materials and construction techniques, and security and protective systems (Fig. 2). In this regard, it is suggested that stucco artifacts of similar types be grouped in the same enclosure, accompanied by explanations regarding the excavation period, historical era, and probable function of each piece. Furthermore, the pieces should be categorized according to their design and motif and displayed in separate enclosures.
The primary factors for physical and chemical preservation in museums include the monitoring of temperature, relative humidity (RH), and fine particulate pollutants, and careful supervision of environmental conditions is of high importance (Mansourzadeh & Hatami, 2017: 289–302; Rahmani-Garmi, 2011: 62). To control the environmental conditions at the site where excavated artifacts are housed, monitoring tools such as thermometers and hygrometers should be used. Additionally, the implementation of air conditioning, protective measures, and museum security systems is essential.
In the case of the Zahhak Castle site-museum, comprehensive preservation of the artifacts is particularly important because these items are part of a valuable historical heritage, and proper care and maintenance are necessary.
The main factors in the preservation of artifacts in museums include both physical preservation and protection against chemical agents (Mansourzadeh & Hatami, 2017: 289–302). Careful monitoring of environmental conditions, including temperature, relative humidity (RH), and fine particulate pollutants, is one of the most important measures for safeguarding collections (Rahmani-Garmi, 2011: 62). To control the environmental conditions were excavated artifacts are housed, the use of monitoring tools for temperature and relative humidity, such as hygrometers and thermometers, is essential.
Furthermore, the implementation of ventilation systems and comprehensive protective and security measures in the museum, especially at the Zahhak Castle site-museum, must be thoroughly considered, as the excavated artifacts are part of a valuable historical heritage and their preservation is essential.
Regarding the Zahhak Castle site-museum, since the site’s temperature rarely reaches 40 °C—which typically does not cause phase transformations in gypsum—there is likely no significant concern about the deterioration of the stucco artifacts due to heat. Similarly, considering the low concentrations of chloride and nitrate ions in the stucco samples, the likelihood of phase transformations in the artifacts is also reduced. However, it is still recommended to maintain the temperature and relative humidity at approximately 20–25 °C and 40–50%, respectively, to prevent potential damage to these works.
To improve the storage conditions of the stucco artifacts in the Azerbaijan Museum’s repository, it is necessary to use an automatic air ventilation system that operates several times a day at predetermined intervals to remove excess humidity from the storage environment. Therefore, to monitor the temperature and humidity in the repository, the use of temperature and humidity data loggers is essential for recording and surveying environmental conditions, allowing precise control over storage parameters. Seasonal analysis of the data collected from the temperature and humidity data loggers, as well as air treatment systems, can help prevent damage to the stucco artifacts and minimize structural deterioration of the pieces.

Conclusion
This study demonstrates that the degradation processes have not significantly altered the structure of the stucco decorations at Zahhak Castle within the site-museum. Examination of the crystalline structure of these artifacts, both at the site-museum and at the East Azerbaijan Archaeology Museum, indicates that structural changes in the stucco were likely limited to the pre-excavation period, during the burial of the artifacts in soil, and that no substantial changes have occurred from the time of excavation (2003) to the present (2024).
Harmful anions, such as chloride and nitrate, are present only in minor amounts in the Zahhak Castle stucco, which slows down the processes of dissolution and recrystallization of the gypsum artifacts. Despite the anticipated lack of significant changes in the artifacts at the site-museum, it is recommended that these pieces be placed in standard display enclosures and maintained under stable temperature and humidity conditions to prolong their lifespan.
It is noteworthy that the stucco decorations at the site-museum generally lack distinctive designs or motifs, and most intact samples have been transferred to the repository of the East Azerbaijan Archaeology Museum. The primary reason for this transfer was the absence of a secure storage environment at the site-museum. It is expected that the installation of temperature and humidity data loggers, security equipment, and the use of standard display cases will improve the protective conditions of the site-museum.
Furthermore, the absence of specialized staff at the site-museum leads to confusion among visitors and the loss of opportunities to convey valuable information about the artifacts. Access to Zahhak Castle is only possible via challenging routes, which, combined with the lack of expert personnel, may reduce visitor motivation. It is therefore recommended that the artifacts be preserved near their original locations, with suitable conditions for display and protection. Similar artifacts should be kept in designated, separate enclosures from other types and displayed on shelves accompanied by complete information regarding their condition at the time of excavation and their probable function.