In this paper, the conservation of the Alexander Hamilton Monument by John Angel from the Chicago Park District and the Ferguson Monument Fund will be discussed. The monument was installed in 1952 and was re-gilded in 1983. By 2015, over 80% of the gilding had failed and fallen off. Successful gilding of outdoor monuments requires very thorough surface preparation in order to remove all chlorides and active corrosion products. Inter-granular corrosion is a particular problem that is often difficult to resolve. In order for gilding to last, a bronze has to be as corrosion-free as possible. Traditional surface preparation techniques such as media blasting and ultra high-pressure washing carry the risk of causing physical changes to surface topography of the metal, closing surface pores and embedding salts. They may also leave active chlorides behind. In comparison, laser cleaning is more environmentally friendly as there is no contaminated media waste disposal and the precision and control during cleaning is unparalleled. The results of laser cleaning and surface preparation for re-gilding using the new tunable 1064nm pulsed G.C. Laser Cleaning Systems, specifically designed for art conservation treatments, will be presented.

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(2015) New trends in art conservation, the use of lasers to clean as well as generate an augmented reality representation of an iconic public monument in bronze: The AlmaMater, Studies in Conservation, 60:sup1, S65-S72,

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At the Neolithic archaeological site at Liangzhu in China, located 16 kilometers northwest of Hangchou in Cheking province, many objects of stone, jade, and black pottery were discovered between 1936 and 1939. While the exact date of the Liangzhu culture is uncertain, it is considered to be between 3500 and 2000 BC. A characteristic feature of the Liangzhu-culture pottery is a thin black finish and a layered structure of the body consisting of a black core sharply changing to a gray or red band ending in the black surface.The focus of this paper is to explain why the cores of the vessels are black and why the colored bands occur and what they indicate about the firing conditions of the pottery. Analyses were ca rried out using SEM, electron-beam microprobe, X-ray diffraction, photo-electron spectroscopy, and polarizing microscopy. From this evidence, it is clear thait a clay vessel containing abundant charcoal was thrown on the wheel and then fired under reducing conditions so that charcoal was retained and iron reduced. Just before completion of the firing or during the cooling phase, air was allowed to enter the kiln and a limited thickness of the outer core was oxidized. Then, for decorative purposes, the surface was heavily smoked, and/or a thin iron-containing slip layer was reduced in smoke and burnished.