銅質雕塑作品的黑斑病與修護：以李光裕〈龍〉、〈蛻變〉二件作品為例

The Black Spot Disease of Copper-Based Artworks and its Conservation Treatment: A Case Study of Two Brass Sculptures–Dragon and Metamorphosis by Kuang-YuLEE

銅質文物的鏽蝕會形成不同的種類鏽蝕物，如在銅器表面形成疏鬆淺綠色氯化銅的惡性鏽蝕，氯化銅接觸水分後會形成鹽酸，鹽酸再與銅反應形成氯化銅，反覆的化學反應循環，持續反應使其粉化，此種劣化又被稱為青銅病，這種鏽蝕已有許多案例以及研究調查。另外一種鏽蝕，是像美國自由女神像外表形成的良性綠鏽－鹼式碳酸銅，可以保護下方銅胎不會繼續鏽蝕。不過本研究中的黑斑病是臺灣目前金屬文物保存文獻中，較少提及到的鏽蝕案例，其特徵是在銅像上形成許多黑色的硫化銅鏽斑。多數博物館在預防性保存維護方面，除了溫濕度的控制，亦會針對館內氣體進行檢測與過濾，文物接觸較少有接觸到硫化氣體的可能性，因此案例也較罕見。然而文中李光裕所做〈龍〉、〈蛻變〉兩件作品為私人收藏，未有與博物館相當的環境控制系統，再加上原作的封護層老化，使作品得與空氣中的硫化物接觸，致使黑斑病發。本文以修護此兩件作品為例，首先進行科學檢測，除了暸解藝術家創作時所用的材料以外，也得知原作封護材料出現劣化的情形，同時針對表面所形成的黑色物質進行分析，確認其為硫化銅推測出作品罹患黑斑病。由於藝術作品具有鑑賞的美感價值，雖黑斑病相對於青銅病穩定，但會影響到作品外觀、觀眾觀看的體驗、藝術家傳達的意圖，因此著手執行黑斑移除的修護作業。文中歸納金屬機械性清潔、化學性清潔、緩鏽、封護的步驟與材料，並從中研擬出適合的修護方案，且詳細撰述修護實作的過程，以期提供未來遇到相似狀況的修護人員實作的參考。

The corrosion products of copper artifacts form in various compositions. For example, the light green and powdery copper chloride excrescences on copper or copper alloy objects are the malignant corrosion products. When cuprous chloride reacts to moisture, it forms hydrochloric acid. The acid then reacts again with the copper itself producing more cuprous chloride which is a cyclical reaction leading the object to powdering. This phenomenon is also well-known as‘Bronze Disease,’which has been extensively researched. Another corrosion product of copper that could be found on the surface of Statue of Liberty is benign corrosion-- copper carbonates. This kind of rust will protect the statue from further corrosion. However, the‘Black Spot Disease’discussed in this research is seldom mentioned in the literature on the conservation of metallic artifacts in Taiwan. The defining character of Black Spot Disease, as its name suggests, is the formation of numerous dark spots on copper-based objects. Most of the museums equip the environmental control system to maintain the temperature and humidity and also monitor and filter the harmful gases. In contrast, the two cases-- Dragon and Metamorphosis by Kuang- Yu LEE-- studied in this research are private collections and were stored in a domestic environment lacking sophisticated environmental control systems typically found in museums. Combined with the aging of the original protective coating, these artworks have come into contact with sulfides in the air, leading to the onset of black spot disease. This paper is a case study of the conservation of these two artworks. Firstly, the artworks undergo scientific analysis not only to investigate the materials used by the artist but also to identify the degradation in the original coating materials. The black substance formed on the surface is examined at the same time, confirming it as copper sulfide and indicating that the artworks are afflicted with black spot disease. Although Black Spot Disease is relatively stable compared to Bronze Disease, it still impacts the appearance of the artwork, the viewing experience of the audience, and the intent of the artist. Due to the aesthetic value of the artworks, the conservation treatment-- removal of the black spots is conducted. The paper summarizes the steps and materials for mechanical and chemical cleaning, corrosion inhibition, and protective coating, and devises suitable treatment proposals. It also details the implementation process in order to provide guidance for future conservators facing similar situations.