1 INTRODUCTION

The conservation of severely corroded copper alloys (the historical term “bronze” will be used hereafter for the more accurate term “copper alloy”) and the stabilization of active “bronze disease” are two of the most difficult problems facing the archaeological conservator. A survey of the conservation literature reveals that these problems are not new and that treatment methods and philosophies have changed during the past century. This paper looks at the evolution of the treatment of ancient bronzes in the United States as reflected in correspondence, unpublished documents, and selected publications found in the archival records and library of the Walters Art Gallery, Baltimore. A review from this perspective seems fitting, since Henry Walters, who built the Walters Art Gallery in 1904, was one of America's foremost collectors of ancient bronzes, and he demonstrated a deep concern for their preservation. His concern was perpetuated when, at his death in 1931, his museum was bequeathed to the city of Baltimore, and within three years a technical laboratory was created that established the treatment of “bronze disease” as one of its first research priorities. Throughout the history of what is now the Walters Division of Conservation and Technical Research, the conservation of bronzes has remained a high priority.

This paper also attempts to address the role that science has played in changes in treatment methods and goals for bronze over time. Surprisingly, although the scientist was central to the development of early treatments for ancient bronzes and to advancing understanding of the corrosion processes, there is still no permanent cure for “bronze disease” that can be considered safe for the artifact. However, it should be acknowledged that science has brought a profound change in the philosophy of treatment of archaeological materials. By demonstrating what can be learned through examination and analysis of the object with its burial accretions, the scientist has caused a re-evaluation of treatment goals. The emphasis has moved from restoring an object as closely as possible to its original state to using an object as a primary research document for learning as much as possible about its historical context, technology, use, and environment. This emphasis prevails even in classical archaeology collections that have unprovenanced materials for which the composition of the metal, the encrustations, and residues in the patinas may be the only clues to original context and association with other related objects.

The scope of this paper is limited largely to observations based on source materials found at the Walters Art Gallery. Although it does not provide a comprehensive history of the treament of ancient bronzes, it presents material that might not otherwise be readily accessible. One of the primary values of such a review lies in enhancing an understanding of the effects of earlier treatments and the possible consequences of those we carry out today. It is hoped that this paper will encourage other conservators to review their files and add to the body of knowledge on this subject.