Jamie Clapper Morris, an associate at Wiss, Janney, Elsther Associates, Inc. presented this paper on behalf of Deborah Slaton, principal at Wiss, Janney, Elsther Associates, Inc. and herself.
Les Quatre Saisons is a mosaic by artist Marc Chagall, which is exhibited in a public plaza in the Loop district in downtown Chicago. It was a gift from Chagall to the people of Chicago in 1974, and it is located at the Chase Tower Plaza (formerly First National Bank of Chicago Plaza). The mosaic has tesserae placed on precast concrete panels with more than 250 colors. It was constructed in the Byzantine Style and assembled in southern France.
The original maintenance on this piece included biannual cleaning and annual sealing with silicon sealant. In 1988, the roof of the mosaic had completely deteriorated with 25% loss on the west side. In order to repair it, granite panels were put on the roof. In places where tesserae had fallen off, they were reinstalled in slightly different way in order to distinguish it from the original. In 1993, a bird deterrent gel was added but then removed because of staining. Visual assessment and lab studies were performed, including chemical analysis and scanning electron microscopy studies. The majority of the distress was on the west side. From 1995 to 1996, repairs were being performed on the adjacent plaza, and the mosaic was protected with an enclosure. A protective canopy was built for the mosaic, and wind tunnel studies were performed to ensure maximum protection. When repairing the mosaic, a lot of tesserae from the roof were used. The canopy was finished in 1996.
From 2009 to 2010, facade cleaning and limited condition assessments were performed, including some sounding and field microscopy. Expected distress was found. In 2011, a more detailed assessment was performed and it was sounded at 100% with xylophone mallets. Some expected distress included efflorescence and mortar loss. Limited maintenance was performed, including removing general atmospheric soiling, graffiti, and bird deterrent (which didn’t work). It was surface cleaned, and the graffiti was removed with acetone and water. Areas of loss were repaired and tesserae were re-installed. Ongoing maintenance is recommended.