Study of Pigments in Decorations of Exterior Porch Painting in Soltanieh Dome of Zanjan

There are many art works of the Mongol Ilkhans period in Iran that are unique in architecture and decor. Zanjan Soltanieh Dome is one of the most important monuments of this era that has various decorations. One of the most beautiful and unique examples of decorations in this building is the special art of painting, which is decorated with colored layers and in the thin layer on the brickwork on the outer porch of this dome and on the plain of Soltanieh. Although in the preceding Seljuk period, the use of gypsum as a lime was relatively common and customary, this type of arrangement reached to its perfection in the period of the Ilkhani. Hence, one of the most prominent features of the Ilkhani architecture was the superb skill in casting of gypsum and its manipulation in many different ways. With the spread of gypsum in the 8th century AH, this method has been used to cover the walls with decorative designs. In the period of the Ilkhani, white dressing usually came with tiny levels, so they kept these smooth surfaces rarely completely white and simple. In general, the use of color is more common in this period, as in all kinds of practices, staining of motifs and in flat surfaces, the use of illuminated paintings of the species was common with a wide range of colors. Soltaniyeh domes include various black, white, red, yellow and gray colors, which have not yet been studied in terms of color combinations to identify the pigments and substrates used in them. The questions are about their color combinations and certain features that have been remained untouched by environmental factors. Identifying this sample of colors has a significant impact on creating their proper protective conditions. Since this dome is in open-air environment, it has been affected by the environmental degradation factors. The purpose of this study was to identify the color combinations of these decorations, which were used for the identification of elemental and combination of color ingredients using FT-IR and XRF analysis techniques. Today, the use of various laboratory techniques for the recognition of compounds in the field of restoration and protection of historical works is routinely practiced. A remarkable contribution to better understanding and better studies has been made. Using the instrumental techniques is an appropriate step to improve the selection of therapeutic effects. Based on the results obtained, the pigment compounds were red, yellow, black bone and calcium carbonate, which have been used on the plaster bed. These pigments have a mineral structure and therefore, have a longer shelf life than organic pigments against environmental degradation factors. This has led to their long-term survival in the external environment. It is also noteworthy that there is no protective layer on them. Nevertheless, their resistant structure is the main reason of surviving these works.