The Chicago Conservation Center (CCC: Dr. Margaret Nowosielska, Chief Mural Conservator, and Dorota Bobek, Associate Mural Conservator) performed test-cleaning on the third archway from the east on the north side of the sanctuary. Approximately 60% of the west half of the arch was cleaned, while the east half was partially treated to illustrate the three phases of the conservation process:
Initial Phase used a dry eraser to remove surface grime;
Secondary Phase used a mild detergent to remove soot and grime;
Final Phase removed embedded grime and discolored varnish using a combination of solvents.
Some inpainting was done in areas of particular deterioration and the surface was finished with a protective layer of varnish, which is reversible and can be removed in the future, if need be, without harming the original paint layer.
CCC performed conservation work and cleaning on the third archway mural from the east and the first archway scripture from the east, both on the south side of the sanctuary. The same techniques and solutions were used on these murals as were used on the north side mural. Additionally, as the lettering was illegible after cleaning, this portion of the mural was reinforced by first applying an isolating layer of varnish to act as a protective barrier over the letters, and then overpainting the letters with reversible tempera paint in a light blue-gray tone.