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The metal industry requires different levels of knowledge, starting with knowing where and how to source it, separating it from other components, creating a metal type by alloying two or more types of metal ores, being familiar with the preparation process, melting temperatures of each metal type, the cooling technique and which metal is better suited for the job ahead. All the above refers only to the basic requirements for metal working, where in addition to these skills, metal object producers had to have a knowledge of the finishing and polishing methods, as each metal type was treated differently.
After the preparation of the metal, it was time to produce the metal beads using one of the following techniques.
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Casting
Casting entails the use of molds after melting the desired metal in a crucible. In the case o metal eads it is more probale that closed molds were chosen to obtain the desired round shape with a perforation in the middle.
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Metal sheets technique was used to produced gold beads (J1.25). To make a sheet metal, a sufficient amount of metal, usually silver or gold, are placed between two layers of cloth and hammered gently using a hammer or a similar instrument. When the metal hardens, it is reheated, dropped in cold water and hammered again until reaching the desired thickness (Ogden 1982: 34). In the case of bead J1.25, it was then wrapped on its axsis to form a shell shape.
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Finishing and Polishing
The final step of production to smooth the surface and get rid of any tool marks, scraps to the surface or soldering marks and polishing the surface to give it a shiny finish. This could be achieved by mixing ground charcoal or sand with some type of oil or liquid resin (Ogden 1982: 86–87).
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Stone beads production technique
Different techniques have been implemented for working the different types of stones and materials. The stone needed to be shaped by chipping technique using a stone chipper or a grinder, before drilling the perforation, especially considering that many stones were imported as bulks of raw materials like Lapis lazuli for example, which was brought uncut in large chunks. A reference to the lumps of Lapis lazuli is mentioned in the Sumerian poem Enmerkar and the Lord of Aratta “Let them cut the pure lapis lazuli from the lumps” (Cohen 1973: 113; Moorey 1999: 88), and archaeological evidence is found in Ebla, where a large amount of raw Lapis was recovered from the royal palace (Pinnock 2006: 248).
Probably the most technical aspect of bead making was drilling the perforations. The archaeological record and the study of techniques reveal that there was more than one type of drill.
1- The hand-held drill which is a microlithic chipped stone drill bit, hafted to a bone or wooden handle to form an awl, and performs at a low-speed.
2- The bow drill bits , introduced in the Neolithic period, is a hafted microdrill-bit and the wooden fire-stick rotated between the palms of the hands increased rotational speeds, perhaps by as much as 40 times. With the addition of a string wrapped round the hafted drill-bit and pulled backwards and forwards, speed was increased as high as 850 r.p.m (Moorey 1999: 107-109). It is important to mention that none of the drills mentioned here achieved a perforation less than 3mm in diameter (Moorey 1999: 108).
In order to better understand this process of drilling stones, a local jewelry maker was consulted. According to him, some stones like carnelian and obsidian are very hard to drill, especially using hand drill, because the pressure that the operation puts on the stone can cause the stone to crack or break. In order to avoid that, they would drill the stone bead from both ends at the same time to relieve some of the pressure. This is not an easy task, he said, and when he was an apprentice, and attempting to do a similar operation, the results were not always satisfying, as it takes practice to drill from both ends and have as a result a uniform straight perforation. Making the two drill meet in the middle, take practice and precision.
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Finishing and Polishing
As for the polishing, sand and oil mixed together can give good results. However, it is not very clear what could have been the technique used to polish the beads in the case of mass production, because this process takes time to obtain a clear, smooth and shiny surface, so it would not be very efficient on an industrial level. Ogden suggested that for the mass production, several beads would be strung and rolled on abrasive material. (Ogden 1982: 150)
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Shell bead production technique
An interesting experiment by Peter Francis Jr was conducted to determine which of the ways to perforate the shells were used and how functioning these methods are. The author experimented with goring, where a pointed tool is pressed and turned to make a perforation, scraping using a tool to scratch the body and make a hole, sawing with a blade and grinding where the shell is rubbed against a hard surface, and concluded that all these methods were efficient in making a perforation in a shell (Francis 1982: 25-29).
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