Messianic Era, detail

Cleaning process (continued)

With the wax removed, the paint was left with a frosty appearance caused by a film of grime that remained on the surface. Conservators found the grime to be water-soluble and formulated an aqueous (water-based) solution to remove it. The aqueous solution contained a chelator, trisodium citrate, to help dissolve dirt efficiently. The conservators then used plain water to remove residues of the trisodium citrate. The pH of the cleaning solution was maintained at 6.5. This slightly acidic pH level provided an ideal environment for the chelator to function while preventing damage to the oil paint layer.
Messianic Era; note the improved saturation on the formerly frosty cleaned area. (2003 photo)
The Triumph of Religion