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296 Chapter 23 Amalgam Gilding in Khmer Culture Emma C. Bunker Abstract Amalgam gilding is a chemical gilding technique, sometimes referred to as fire gilding. It was first developed in ancient China around the fourth century BCE by Daoist alchemists to make gold from base metal. To date, there is no evidence that amalgam gilding was known or practiced by the Khmer until the late seventh or eighth century, which seems extremely late for a culture where gold was a major feature of elite life. When, why, and from whom did the Khmer learn amalgam gilding, and where did they get the mercury ore, as it was not found within Khmer territory? A study of these questions reveals aesthetic, economic, religious, and technical aspects of Khmer culture that beg for attention. Gilding Techniques Used by the Khmer Khmer metalworkers practiced two distinctly different methods of gilding. These were foil gilding and amalgam gilding. Foil gilding was practiced in mainland Southeast Asia around 250 CE, but amalgam gilding was not known in mainland Southeast Asia until the seventh or eighth century. Foil Gilding Foil gilding is a mechanical technique accomplished by overlaying base metal with gold foil that is attached by wrapping, riveting, or hammering it with a punch so that the foil is forced into the base metal’s surface. Beads formed by wrapping gold foil around a clay core were excavated in northeast Thailand at Noen U-Loke, an Iron Age tomb dated roughly to 250 CE, providing the earliest known archaeological evidence for the technique in mainland Southeast Asia (Higham 2002, 2001; Higham and Thosarat 1998: 153–5). An Iron Age bronze helmet recovered near the northern end of the Tonle Sap in Cambodia is described as having gold decoration. The helmet has disappeared, so the possibility that the decoration might have been foil cannot be confirmed (Higham 2002: 214). Gold foil once covered the lips of the famous seventh-to-eighth-century Khmer silver Vis .n .u head found near Wat Phu in southern Laos (Giteau 1976: pl.139). The head, now lost, once belonged to Prince Boon Oum of Champasak who took it in the 1980s to Paris where he subsequently died. Leaf Gilding Leaf gilding, a more advanced version of foil gilding, was later used by Khmer metal-smiths. Gold could be hammered into an extremely thin sheet, known as leaf, only a few microns thick. Gold leaf was used decoratively to gild specific details, such as the cakra and diadem on a late tenth-century bronze Vis .n .u image (Bunker and Latchford 2004: 202–3). 23 ISEA.indd 296 6/6/08 10:37:15 AM 297 AMALGAM GILDING IN KHMER CULTURE Amalgam Gilding (for past publication on the subject, see Oddy 2000: 16–19) Amalgam gilding is a chemical process that is basically unrelated to the mechanical foil and leaf gilding processes, except that the gold used for amalgamation may have been hammered into foil or sheet before being cut into small pieces to mix with the mercury. Amalgam gilding is achieved by dissolving gold in mercury to make a paste that is applied to the base metal to be gilded. The base metal is then heated, the mercury burns off, and the resulting gilded surface is burnished. A surface that has been amalgam gilded but not yet burnished has a typically porous and granular appearance. The base copper alloy to be gilded should be high in copper with little or no tin and preferably no lead. Unalloyed copper allows for relatively easy bonding of amalgam gilding to its surface. Mercury (Hg) The raw material needed for amalgam gilding is, of course, mercury, popularly known as quicksilver. Mercury is a heavy, silver-white metallic chemical element that is liquid at ordinary temperatures, and has the property of dissolving other metals, forming an amalgam. Mercury was commonly obtained by distillation from cinnabar, a mercuric ore not found in the lower Mekong Basin (Workman et al. 1972: 134). Such a deficiency may have been a major contributing factor to the late development of amalgam gilding in Khmer metalworking centers. Khmer Examples of Amalgam Gilding The corpus of early Khmer artifacts enhanced by amalgam gilding is fairly small, and frequently without provenance, compared to the vast number of stone and plain bronze artifacts. From the information available, amalgam gilding does not appear to have played a major role in Khmer art until the Baphuon, Angkor Wat, and Bayon periods of the eleventh...

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