Treatments of Corroded Lead Artefacts AN OVERVIEW

In the past, corroded lead objects have been treated in many different ways. Some treatment methods are based on cleaning the surface, and rely on the dissolution of the stable corrosion layer. Other methods involve the conversion of the corrosion products into metallic lead, and have been used to preserve the design, which is still present in the corrosion layer and which contains information of the original surface. Such techniques work particularly well on lead objects that have been exposed in a humid environment containing organic acid vapours, where an active corrosion crust is likely to develop. The volume of the corrosion products in an active corrosion crust is greater than that of the original metal, resulting in cracking over time, thereby increasing the access of pollutants to the metal below. This overview describes the different treatment methods applied to lead objects; it is not intended to provide practical guidelines with regard to the conservation of lead objects.