A technical study of comparative of Ghiasieh Khargerd school tiles with traditional contemporary tiles of Mashhad

The art of tiling in Mashhad has a long history. Religious buildings such as mosques and tombs are always decorated with the best tile decorations.
 Especially Goharshad Mosque and the holy shrine of the eighth Shiite Imam, which has a special decorative and religious status, are the manifestations of traditional tiling in this art-rich region. Tiling in Mashhad has its own style, both in terms of decoration and composition of materials and their construction method. Traditional tile makers in Mashhad use a type of tile that is known as stone tile today. The use of glass powder, silica powder and a type of bentonite instead of clay in the body of these tiles is the reason for this name. It seems that this method of production in Mashhad has a long history. A technical study of the remaining tiles in the buildings of this area (which belongs to the past) can help us prove the above hypothesis. Therefore, the tiles of Ghiasieh Khargerd School were studied, which is historically attributed to the architecture of Greater Khorasan and is a twin of Goharshad Mosque in Mashhad. Both are made by Qavam al-din Shirazi and are very similar in terms of decoration and craftsmanship. Unfortunately, Goharshad Mosque does not have tiles at the time of construction because this mosque has been restored many times. But Ghiasieh Khargerd School has tiles belonging to the time of its construction (ninth century AH) and can provide us with laboratory samples. The method of this research is laboratory based using technical study of works. In this research, samples are measured in terms of the type and composition of their constituents by laboratory techniques. First, the method of making contemporary tiles in Mashhad is described and their materials are introduced. Then, laboratory studies are performed on old samples taken from the Ghiasieh Khargerd School building.The identification of body tissue and glaze was conducted through the use of an Olympus PM G3 optical microscope, while the alkaline melting method and point analysis with the SEM-EDX device were employed for chemical analysis.
 The results show that the body of the mosaic tiles for Ghiasieh Khargerd School is similar to the contemporary stone tiles of Mashhad in terms of chemical composition and texture. In terms of glazing method and tile sintering method, according to histological studies by optical and electron microscopes, similarities are not fully confirmed. In this respect, Moaqqali tiles, Hamil tiles and seven-color tiles are more similar to clay tiles that Mashhad tile makers are currently using to make seven-color tiles. The composition of glazes, the type of glaze colors and how they are used and produced do not fully confirm the methods currently used by Mashhad tile makers. In general, studies show that the methods and techniques of the past (with a slight changes in terms of the composition of materials and methods used in their construction) have been continued over the past years by contemporary tile makers in Mashhad.