William Donnelly showing Melissa King, WUDPAC Preventive Fellow, and I different tools for polishing silver objects. Image courtesy of Katie Rovito.
Seminar taught by William Donnelly, Conservation Assistant and Affiliated Instructor at Winterthur/University of Delaware Program in Art Conservation, and Katelyn (Katie) Rovito and Tia Polidori, IMLS Conservation Assistants at Winterthur Museum, Garden & Library. 

This seminar covered chemistry of silver tarnish, preventive care, stabilization treatments, and lacquering options for silver objects.

At the beginning of the seminar, Tia and Katie introduced workshop participants to decorative silver artifacts and the different means of silver plating, such as fuse plating and electroplating. They provided instructions on how to tentatively identify each type using visual queues. Knowing the method of manufacture indicates how the silver artifact can be cleaned (e.g. fused plating is thick enough so that it can be abrasively polished). William, Katie, and Tia also explained how current studies are using X-ray fluorescence (XRF) analysis to indicate date of manufacture by looking at elements present: pre-1850 silver will contain mainly silver and copper with trace amounts of lead and gold; after-1850 sterling silver is will typically only show silver and copper.

This silver spoon's lacquer coating was removed with steam and solvents, cleaned and degreased, and polished mechanically. Photo shows object with tarnish partially reduced.

Cleaning and polishing silver can be complicated depending on the means of manufacture and types of decorative finishes present, such as gilding. Cleaning gilt silver is difficult due to the thinness of gilt layer, that it can be easily mistaken for tarnish layers and polished off.

The seminar included a practical session where we tested various mechanical and chemical cleaning options, removed aged lacquer coatings, and applied fresh lacquer by brush.

Natalya Swanson