The Technology of Making Roman Head-Flasks by Studying on Preserved samples in the Glassware and Ceramic Museum of Iran

Abstract
Roman glass art in the first centuries AD is very valuable and can be studied in terms of manufacturing and decoration techniques and technologies related to glass art. Flasks in the shape of human head are part of the Roman glass collection with mold-blown technique in the 1st and 2nd centuries AD, which six examples of these works are kept in the glassware and ceramic Museum in Tehran. This article, with the aim of identifying and studying the methods of making Roman head-flasks in glassware and ceramic Museum of Iran, tries to answer this question that what kind of technology was used in making Roman head-flasks? Therefore, this research in terms of purpose is applied research in terms of the assence and method is descriptive-analytical research. The method of collecting its data was library type and recording the observations and experiences of the Authors. In the results of this research, it was found that the art of Roman glass in the first century AD was influenced by the familiarity of the Romans with the methods of sculpting, molding and benefiting from them in making and decorating glass works. The mold of the Roman head-flasks of Iran’s glassware and ceramic Museum was made using advanced modeling and molding methods, and then it was made by glass blowing. There are three different manufacturing methods based on the main body of these works, in the first method, two-piece molds are used to make the overall form. In the second method, their base was added as an additional part to the work, and in the third method, additional decorative strips were used to make the base and opening of the head-flasks. All the samples in the glassware and ceramic Museum of Iran were made by the first way and in one piece with the benefit of two or three piece molds.
Keywords: Construction Technology, Head Flask, Iran Glass and Pottery Museum.
Introduction
Research question and hypothesis: The Roman head flasks in the glassware and ceramic Museum were made exactly in the first years after the invention of the blowpipe, they have valuable dimensions for study. It seems that the method of making these works is the type of blowing in complex multi-piece molds, which is considered the main hypothesis of this research. The main question of the research is what kind of technology was used in making Roman head-flasks? Therefore, the Authors were eager to recreate a sample of Roman head-flasks for research in the technology of making these works.
One of the main components of the transformation and development of Roman glass art in the early centuries AD was the expansion of the use of molds in the creation of works. In the first century AD, they used the capabilities of glass blowing in combination with the capabilities of glass casting and pottery molding in this process. Glass molds were made based on the remaining samples from materials such as clay, stone, wood and metal. The molds were often several pieces, and after blowing the glass in it, they were separated from each other and the final product came out.
Identified Traces 
The process of making blown glass works was influenced by the molding methods used in pottery. The use of a mold to make glass works was noticed by Roman glass makers immediately after the invention of the blowpipe. Fruit, animal and human head shapes are used in the design of blown containers. In the design of these works, the creators have often reused patterns found in ceramic and metal containers or copied shapes that were used for centuries, which were often animals and human heads.
Paying attention to the shape of the human head in the design of molded dishes is a characteristic of the development of Roman sculpting and molding methods in the early centuries AD.
There are three types of head-flasks in terms of appearance; One-face construction, two identical faces on both sides of the bottle and three identical faces in the same sizes can be seen. The third mode is very rare and valuable.
By studying the samples of the head-flasks in the glassware Museum of Iran, it can be seen that the size of this group of works is about 8 to 10.4 cm. Often, blue or transparent colors are used with colored base. Two examples of these head-flasks are single-faced, and on the back of the bottle, the pattern of decorations and hair arrays can be seen in the form of a mold. Three examples of this collection of works contain two faces that are created on both sides of the bottle in a similar way using a mold. A very rare and valuable example of this collection is the head-flasks with three faces, which is repeated with a very regular and precise distance around the bottle. In this example, curly hair decorations are emphasized.
In the construction of all the samples, except for sample A.634, a two-piece mold was used, and because of the purchase of these works from the collectors of historical objects by the museum, the place where it was found is unknown. Due to formal similarities and historical studies, the place of creation of these Eastern Mediterranean works is recorded in the museum certificate.
The reconstruction of an example of a head-flasks made it clear that the technology of making multi-piece and complex molds made of clay was common in Roman art in the first century AD, which was first used in making clay and then glass-shaped bottles. According to the abundance and variety of glass samples of head-flasks, it can be concluded that glass samples were more popular and widespread.
Conclusion 
Based on what was presented in the content of the article, it can be said that research has been done; In terms of manufacturing technology, the widespread use of molds at the same time as the invention of glass blowing is attributed to the first century AD during the Roman rule. At every stage, according to the invention of new ways of making glass, the glassmaker has benefited from the abilities of other fields such as pottery and metalworking to diversify and develop his works. In such a way that the use of common molds in ancient Roman pottery leads to a kind of parallel use for making glass samples of such synergistic developments.
Re-creation of manufacturing technology in the form of a case example of head-flasks, this research showed that Roman glassmakers in the first century after inventing the method of blowing glass by using the molds common in pottery art made these works. and based on archeological evidence, the molds used in the construction of these works were mostly made of clay in two or three pieces. After blowing the glass in the mold, the glass maker shapes the opening and the bottom of the mold. In the continuation of this research, it is suggested that Archaeometric studies be carried out in relation to the constituent elements and structure of the studied glasses in the country, because the process of re-creation, apart from the issue of shape, can be done in the form of Archaeometric studies on components and materials. The manufacturer also emphasizes.