Active Corrosion of Museum Objects Made of Lead

Abstract

White powdery corrosion deposits on the surface of lead objects are diagnostic signs of active lead cor­rosion. It has been established that these deposits are corrosive minerals cerussite and hydrocerussite. They appear on lead artifacts during storage and display, even on objects after conservation treatment. It is known that active corrosion on lead develops in acetic acid vapor. However, it has been observed that active corrosion appears in absence of acetic acid vapors in environment. The article discusses various mechanisms of the oc­currence and development of active corrosion on lead objects. The given chemical reactions demonstrate that in conditions of high humidity in the presence of oxygen and carbon dioxide, the appearance of white powder formations of cerussite and hydrocerussite on museum lead objects is possible without the involvement of acetic acid.

Keywords

• archaeological lead
• museum lead objects
• lead corrosion
• active corrosion
• cerussite
• hydrocerussite
• metal conservation