Restoration Methodologies

TRIAL RESTORATIONS

Begun in 1991 in order to perfect restoration methods in consideration of the various painting techniques revealed in the diagnostic phase.

RESTORATION

Begun in 1993 with the first interventions performed on the cross vault painted by Bicci di Lorenzo which presented in more serious form the same problems of the Piero della Francesca frescoes.(See bibliography).

Phases of Restoration:

Removal of black smoke and polluting particles followed by fixing of color and preparatory consolidation of areas at risk

Removal of plaster added by Leonetto Tintori in the areas treated without color (c. 70 square meters out of a total of 300 square meters) and discovery of repainting done by Gaetano Bianchi and/or Domenico Fiscali

Cleaning phase

Cleaning of the original surfaces with different techniques:

  • areas painted a fresco: application of desolfatizing and cleaning compresses with ammonium carbide;
  • areas painted a tempera : application of desolfatizing and cleaning compresses with ion exchange resins and small concentrations of ammonium carbide;
  • areas painted in "tempera grassa" : application of dsolfatizing and cleaning compresses of ion exchange resins;
  • absorption of yellow stains due to fixatives employed in previous restorations which reappeared on the painted surfaces after cleaning.

Then the final consolidation of the painted surface with compresses of barium hydroxide.

  • Removal of old "ruined" plastering performed with inappropriate materials (cement, gesso, vinyl resins loaded with of inert particles);
  • New plastering with sand and lime-based mortar (washed with deionized water to eliminate residual salts) able to absorb any salts remaining in the original plaster;
  • Consolidation of "loose" original plaster with injections with special pozzolana-based mortar with no salt content.

After touch painting

Touch up painting with various techniques:

  • chromatic selection to reconstruct areas with decorative elements or in any event elements not subject to interpretation;
  • intermediate solution between chromatic selection and abstraction for areas impossible to reconstruct (using a blend of colors from the surrounding area);
  • neutral treatment for larger impossible to reintegrate gaps.

Filmati delle fasi del restauro

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