The conservation of this table clock by David Weber (1623/24–1704) is just one of several recent treatments carried out on the timepieces included in the exhibition Precision and Splendor: Clocks and Watches at The Frick Collection. An horologist had restored the movement in 2003, but the casework had not been treated since 2001.
Conservation of this gilt brass masterpiece required removal of the more than sixty pieces that comprise the outer casework. The clock has nine dials that are made of enamel and silver and often include multiple parts. The dials are attached to gilt brass walls that cover the mechanism inside. The silver dial plates are either intricately engraved or have further punch-work and details below the colorful transparent enamel, creating different textures that reflect the light.
The clock is topped with a slender goddess standing upon a winged orb and further adorned with silver flowers, lion heads, floral mounts, cherubs, and winged goddesses.
The silver components had darkened over time, developing a light brown to black tarnish that was particularly disfiguring to the beautiful basse-taille enamel dials. The contrast between the white of the silver and the transparent colored enamels is essential to a proper understanding of the scenes, which, like the detail of the bear hunt in the video, were transformed after treatment.
The silver was polished using precipitated calcium carbonate. Care was taken during the polishing to preserve the dark lines within the etched plates of the dials. When it was possible, elements were coated with a cellulose nitrate lacquer in order to prevent future tarnishing. Where the enamel had begun to deteriorate, vinyl erasers were used (instead of polishing paste) to remove the tarnish on the silver. This minimized contact with water and solvents in areas of unstable glass. Old discolored restorations on the enamels were also reduced or removed. The gilt surfaces were dusted, then cleaned with a mixture of ethanol and water using cotton swabs.
After treatment, the clock was reassembled and displayed in a case with silver cloth — a product containing activated carbon that absorbs pollutants from the air — and silica gel to maintain a specific relative humidity within the case.
The Conservation Department would like to thank Conservation Intern Molly McLemore for her assistance in the documentation and treatment of this clock.