P. Andrew Lins and Sally Malenka
A number of eighteenth and nineteenth century texts describe the use of mercuric nitrate and other mercury salts as pretreatment (dip or wash) for metal articles that were subsequently fire or amalgam gilded. Such pretreatments were considered to improve the amalgam adhesion or ease of spreading, probably by creating a thin layer of mercury on the substrate. The same mercury-based pretreatments persist in the early literature on electroplating and into the twentieth century. This study examines by experiment the use of mercury compounds and electrochemical dip solutions,investigating:
1. the deposition reaction of Hg(NO3)2 and other mercury salts on silver alloys, and copper and copper alloys.
2. the effect of the mercury layer on the electrodeposition process and on the adhesion of the electroplated layer.
3. the detection levels for such mercury layers and whether they have the potential to confuse some surface analysis techniques intended to separate objects that were amalgam gilded from those that were gold electroplated or gold dipped.
The examination of nineteenth century gold electroplated objects will be discussed.