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Piero
Della Francesca Conservation of Works
Conservation
of Works
- Main
Page
Piero
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NOTES
ON EXECUTION TECHNIQUE AND STATE
OF CONSERVATION
Technique
of execution
The
fresco fragment from the ancient
Palazzo Pretorio, was detached
together with the entire painted
plaster surface in the second
half of the 19th century, and
transferred onto a new support
made of a metal grate drowned in
gesso treated with sizing.
The
painting appears to have been
executed according to the
traditional buon fresco,
technique, with colors mixed in
water and applied to the still
wet plaster. Consequently, during
the drying phase, the calcium
hydrate contained in the malt
undergoes a carbonation process
and, absorbing the colors, fixes
them to the support surface
rendering them more
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resistant to external agents. Only
the saint's mantle, painted with azurite,
was applied directly to the dried plaster
without the usual preparatory red mission.
Analysis
has revealed at least three days of
painting, or three not very large areas of
malt that the painter had to paint before
the plaster dried completely.
In
particular, the hands and face show traces
left by the carbon tacks used in
transferring the drawing to the plaster by
means of the dusting.method. The dusting
technique, commonly used in all of Piero
della Francesca's mural paintings,
consisted of making pin holes along the
outlines of the full-scale preparatory
drawing done on cardboard which, placed
over the plaster painting surface, was
tamped down with a cloth sac containing
carbon powder. The powder, penetrating
through the pin holes, left an image on
the wall of the composition to be
reproduced in the fresco, making the work
easier for the artist. It can be observed
on the hands of the saint that the under
side of the cartoon was placed against the
surface so that the paper was not properly
smoothed down and left its print on the
fresh plaster.
In
the case of the pastoral staff, on the
other hand, it is possible to see the
marks left by direct incision.
The
painter used gold for the halo of Saint
Ludovico, composed of a series of luminous
rays.
State
of Conservation
The 19th century detachment of the
Saint Ludovico was not a completely
successful operation, as is demonstrated
by the precarious state of conservation of
the painting and the numerous deep breaks
in the plaster.
The
present appearance of the fresco is to be
attributed, however, to a more recent
restoration.
It
is quite likely that, after the
detachment, the missing plaster in the
fragment was replaced and the entire
fragment then enclosed within a false
frame, of which there are a few traces in
the lower part of the painting.
Later
the frame and the plaster replacements
were removed and the fresco filled out
with neutral zones in preparation for
insertion in the current wood
frame.
The
initial diagnostic analyses identified a
vinyl resin based superficial fixative
that had been applied to the entire
painting in order to consolidate the
exfoliated paint. Under the fixative the
analysis revealed the presence of shellac,
used in all likelihood during the
detachment operation and not completely
removed from the surface during the
removal of the protective cloths. Between
the two fixatives there are substantial
areas of repainting, effected in order to
hide the many abrasions and gaps in the
paint. Over time these have undergone
alteration, provoking a darkening of the
original colors. The azurite in the mantle
shows numerous abrasions with wide gaps in
the pigment, and its current color is the
result in large part of previous
restorations.
Conservation
The Idea
The
Archive Documentation System (S.D.A.) in
support of the Project (" A Project for
Piero della Francesca") è was
created in 1991 at the same time that the
official announcement was made that the
work of restoration had begun (See, Rome,
Monumental complex of San Michele, Press
conference "La Leggenda della Vera Croce.
L’avvio del restauro. Seconda fase:
dopo le indagini i primi interventi
conservativi" December 19,
1991).
The
System is based on a new idea, conceived
in 1990, with a triple intent:
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activate a permanent observatory of the
conditions of the painted surfaces based
on the knowledge developed during the
preliminary study phase (1985-90), to be
further enriched in the restoration and
future monitoring phases;
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enhance the methodology of restoration by
the addition of a reliable cognitive tool
that would serve both as a support system
and as an "operative arm" with which to
meet the complex challenges in the
conservation and future valorization of
the Piero della Francesca frescoes in
Arezzo;
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constitute a "permanent documentation
center" for future study and diffusion of
information regarding the study and
conservation of the mural paintings of
Piero della Francesca and to construct,
with the use of computer technology, an
organic data base for the Project and an
interactive multimedia system to be hooked
up to the international electronic network
and available for public
consultation.
The
System is a unified structure for the
registration and documentation of all data
produced in each disciplinary area of
research and intervention, pursuant to the
original program of multidisciplinary
research previously designed for the
earlier phases of the Project.
One
of the System requirements is the ability
to carry out an integrated and organic
examination of the documentation through
the correlation of data, especially
between historical information and the
results of the most recent diagnostic
studies of the restoration, in order to be
able to make a direct contribution to the
development of more in-depth information
and more advanced operational methods in
both the restoration and information
fields.
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