The "Tiepolo Frescoes" Project

Preliminary Remarks

In preparation for a Tiepolo exhibition in Würzburg in 1996 investigations were made into the painting technique used by the master on his largest and most significant work, the fresco in the staircase of the Würzburg Residence.  A movable bridge scaffold which made it possible to reach all parts of the painting was set up for this purpose in 1995.

Movable bridge scaffold in the staircase, 1995

It became apparent that the paint on parts of the fresco, in particular in the lower areas depicting the continents (above the main cornice), was powdering and flaking.  In some places paint layers in this desolate condition had already fallen off.  Damaging salts were present on the surface in numerous places.  The condition of the fresco in 1995 is recorded in a comprehensive photo documentation and on a map of the damages.  Before the scaffold was removed emergency measures were carried out to stabilize the extremely endangered areas and test consolidations were undertaken using various binders.  Equipment to measure temperature and humidity was installed and some paint and plaster samples were taken.

Because the wall surfaces and in particular the Tiepolo frescoes in the Imperial Hall also exhibited damages, scaffolds were set up there and investigations were carried out during the summer in 1997 and 1998.  Here, too, the entire extent of the damages became visible close up.  As with the staircase, emergency stabilization work on the paint layer and the plaster support had to be undertaken in some places, climatic measuring equipment was installed and samples were removed.

Description of the Project

The main goal of the conservation and restoration work to be carried out in the staircase and then in the Imperial Hall, beginning in 2003, is to stabilize and preserve the Tiepolo frescoes.  Potential sources of damage such as salts, biogenous substances (mold fungus) and harmful consolidants from previous restorations must therefore be removed, reduced as much as possible, or neutralized.  Areas with detaching or disintegrating paint layers have to be secured and permanently stabilized.

Figure of “Prudentia” in the Imperial Hall exhibits substantial moisture damage to the paint layer

Based on the results of the preliminary investigations (including studies of the room climate, analyses of the plaster, pigment, binding agents and salts, mapping of the location of surface salts, analyses of the binders for fixing agents used in previous restorations, analysis of microorganisms, archival research and literature studies, analysis of the tests made with different consolidation agents, etc.), appropriate materials and methods for removing salts from affected areas will be tested on sample plates and on unpainted plaster surfaces.  Only after that will it probably be possible to begin conservation work on the original painting.  In view of the salt contamination on the plaster and the substantial formation of gypsum by the fresco’s calcite-bound pigments, this task will be extremely complicated and time-consuming.  Furthermore, “classical” restoration measures such as careful cleaning, treatment of cracks and cavities, and possibly also retouching work will be necessary.

In order to sustain the results of these difficult measures it is particularly important that the attic and the windows be absolutely impermeable for precipitation; the most serious of the existing damages developed as a result of missing or non-watertight roofs.