The Relevance of Contemporary Bronze Casting in Ubon
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THE RELEVANCE OF CONTEMPORARY BRONZE CASTING IN UBON, THAILAND FOR UNDERSTANDING THE ARCHAEOLOGICAL RECORD OF THE BRONZE AGE IN PENINSULAR SOUTHEAST ASIA A Thesis by DANIEL EUGENE EVERLY Submitted to the Office of Graduate Studies of Texas A&M University in partial fulfillment of the requirements for the degree of MASTER OF ARTS December 2004 Major Subject: Anthropology THE RELEVANCE OF CONTEMPORARY BRONZE CASTING IN UBON, THAILAND FOR UNDERSTANDING THE ARCHAEOLOGICAL RECORD OF THE BRONZE AGE IN PENINSULAR SOUTHEAST ASIA A Thesis by DANIEL EUGENE EVERLY Submitted to Texas A&M University in partial fulfillment of the requirements for the degree of MASTER OF ARTS Approved as to style and content by: _____________________________ _____________________________ D. Bruce Dickson Norbert Dannhaeuser (Chair of Committee) (Member) _____________________________ ___________________________ Edward Runge David Carlson (Member) (Head of Department) December 2004 Major Subject: Anthropology iii ABSTRACT The Relevance of Contemporary Bronze Casting in Ubon, Thailand for Understanding the Archaeological Record of the Bronze Age in Peninsular Southeast Asia. (December 2004) Daniel Eugene Everly, B.S., University of Houston; M.A., University of Houston at Clear Lake Chair of Advisory Committee: Dr. D. Bruce Dickson A direct historical approach is used in this thesis to document the lost wax casting technique as currently practiced by indigenous metallurgists in northeastern Thailand. The smiths observed at Ban Pba Ao, Ubon Ratchathani Province are the last practicing members of a bronze working tradition that has been in continuous operation at the village for two centuries. An account of the processes used to create bronze bells is provided. Of particular significance is the fact that the yard in which casting activities are performed did not receive clean up operations following the bells production. As a result, hearths, bowl furnaces, crucibles and fragments of clay moulds are left scattered about the yard. These materials accumulating in one location would eventually create a mound of cultural debris. The discarded materials from the lost wax casting process as practiced at Ban Pba Ao provide considerable insight into what might be found in the stratigraphy of Peninsular Southeast Asian prehistoric sites that were involved in the production of bronze objects. The study concludes that attention needs to be paid to the stratigraphic sequences from which bronze artifacts are extracted, rather than relying on iv the artifacts to determine the type of process used in their manufacture. v DEDICATION To my family, who taught me how to love. vi TABLE OF CONTENTS Page ABSTRACT........................................................................................................... iii DEDICATION………………………………………………………………....... v TABLE OF CONTENTS....................................................................................... vi CHAPTER I INTRODUCTION......................................................................... 1 II METALLURGICAL PROCESSES............................................... 6 Elemental Copper………………………………………... 6 Copper Deposits…………………………………………. 7 Native Copper………………………………………........ 9 Initial Copper Ore Use…………………………………... 10 Crucible Furnaces……………………………………...... 11 Arsenic-Copper Alloys………………………………….. 14 Sulphide Ores and Fluxing Agents…………………........ 15 Bowl Furnaces…………………………………………... 17 Archaeology of Furnace Evolution…………………........ 20 Terminal Chalcolithic Furnaces……………………......... 21 Slag-Tapping Furnaces……………………....................... 22 Shaft Furnaces……………………………………............ 24 Ingot Casting…………………………………………….. 26 Tin-Bronze………………………………………………. 27 Physical and Mechanical Properties of Tin…………........ 28 Tin Mining………………………………………………. 28 Alloying Processes………………………………………. 29 Smithing Implements……………………………………. 30 Mould Casting………………………………………........ 31 Summary……………………………………………........ 33 III THE EAST ASIAN BRONZE AGE............................................. 36 Earliest East Asian Metallic Artifacts……………............ 36 Evidence of an Indigenous Origin……………………….. 38 Emergence of Social Stratification………………………. 39 Jade versus Copper as a Status Symbol………………….. 42 vii CHAPTER Page Rise of Centralized Power………………………………. 43 Shang Dynasty………………………………………....... 44 Yangzi River…………………………………………….. 47 Beijiang River…………………………………………… 48 The Zhujiang Delta………………………………………. 49 Bac Bo………………………………………………........ 50 Northeast Thailand………………………………………. 51 Central Thailand…………………………………………. 53 Summary…………………………………………………. 54 IV PENINSULAR SOUTHEAST ASIA............................................. 56 Geographical Description…………………………........... 56 Hydrological Conditions……………………………........ 57 Geological Formations and Soils……………………........ 58 Incorporation into Thailand…………………………........ 59 Laotian Influence……………………………………........ 60 Khmer’s Domination…………………………………….. 61 Funan’s Impact………………………………………....... 63 Water Control Measures of the Khorat Plateau………….. 65 Moated Sites of the Chi River Valley……………………. 66 Moated Sites of the Mun River Valley………………....... 68 Possible Origins of the Iron Industry…………………….. 70 Ban Kan Luang………………………………………....... 71 The Cham Influence……………………………………... 73 First versus Second Millennium B.C. Sites on the Khorat Plateau……………………………………………………. 75 Copper Mining Activity………………………………….. 78 Summary…………………………………………………. 79 V BAN PBA AO................................................................................ 81 Village Description………………………………………. 81 Establishing Contact with the Smiths……………………. 82 Day One Activities……………………………………….. 83 Day Three Activities…………………………………........ 84 Day Four Activities……………………………………….. 86 Day Six Activities……………………………………........ 91 Day Seven Activities…………………………………........ 97 VI THE LOST WAX CASTING PROCESS........................................ 100 viii CHAPTER Page Constructing the Inner Moulds………………………....... 100 Manufacturing the Wax………………………………….. 101 Wax Coating of the Inner Moulds……………………….. 102 Preparing the Wax Coated Moulds for the Appliqué……. 103 Applying the Iconography……………………………….. 104 Removing the Wooden Dowel Handle…………………... 104 Creating Sprues and Handles…………………………….. 105 Sealing the Wax Coated Moulds…………………………. 105 Drying the Sand Coated Moulds…………………………. 106 Constructing the Clapper……………………………......... 106 Mixing the Tempered Clay for the External Moulds........... 106 Constructing the External Clay Moulds…………............... 107 Drying the External Moulds………………………………. 108 Firing the Moulds…………………………………………. 108 Crucible’s Construction………………………………........ 109 Bowl Furnace Construction……………………………….. 109 Melting the Bronze…………………………………........... 110 Pouring the Molten Bronze…………………………........... 111 Removing the Bronze Product from the Clay Mould........... 112 Testing of the Bells’ Sound Quality……………………….. 113 Smoothing the Handle, Bottom and Inside of the Bells........ 114 Polishing the Bells…………………………………………. 114 Finishing the Bells……………………………………......... 115 Fashioning Wind Fans and Attaching the Clappers……….. 115 Final Testing of Sound Quality……………………………. 116 VII SUMMARY OF FINDINGS…………………………………........ 117 Wax Residues…………………………………………........ 117 Bronze Residues………………………………………........ 118 Ingot Casting………………………………………............. 119 Wood Smithing Tools……………………………………... 119 Bowl Furnaces and Crucibles…………………………....... 119 Clay Ovens……………………………………………....... 120 External Clay Moulds…………………………………....... 121 Internal Moulds………………………………………........ 122 Smithing Traditions……………………………………...... 123 Conclusion……………………………………………........ 124 REFERENCES CITED............................................................................................ 128 APPENDIX A…………………………………………………………………...... 130 ix Page VITA...................................................................................................................... 144 1 CHAPTER I INTRODUCTION This thesis investigates the production of bronze objects in northeastern Thailand. A detailed step by step account of the lost wax casting process as currently practiced by smiths in the Ubon Ratchathani Province is provided. The types of residues and discarded materials produced during this particular manufacturing process are reviewed to help determine how Peninsular Southeast Asia’s archaeological record might best be investigated to provide evidence for the particular casting techniques that were used to manufacture bronze objects during the prehistoric period. In northeastern Thailand is the Khorat Plateau, called Isaan by locals but referred to as the “poor house” by those in the country’s lush central valley. The region receives much less rainfall due to being surrounded by mountains and as a result its production of the staple crop rice is considerably less than that of the central valley. Virtually ignored until the late eighteenth century by Thailand’s political system, the region’s people have very strong cultural affinities to Laos, its neighbor to the east. Isaan’s largest urban center, Ubon Ratchathani with nearly a million residents, appears at first glance to be just a smaller Bangkok due to its congested highways and long rows of four story shop houses. Although Thai is the primary language spoken, Isaan, Khmer and Vietnamese can be heard in any given shop one happens into. Unlike Bangkok, in which many of the This thesis follows the style and format of American Antiquity. 2 businesses cater to the tourist trade, shops in Ubon are engaged almost exclusively in the business of supplying