Annealing, distilling, reheating and recycling : bitumen processing in the Ancient Near East

Throughout the prehistory and history of the Near East, natural petroleum tar or bitumen was commonly used for waterproofing, mastic, sealing, mortar, medicine, magic and even warfare. The people of ancient Mesopotamia manipulated this adhesive to lower its melting temperature in order to conserve fuel in an area where timber was a scarce resource. Not only was heat employed to change the chemistry of the bitumen to make it more workable, but the bitumen's chemistry was manipulated so less heat was required to re-melt it. Since the widely-accepted theory that bitumen was a recycled utilitarian good is based upon modern ethnographic examples, the purpose of this paper is to present data and a methodology which will enable a reconstruction of patterns of reuse and bitumen in the archaeological record.