الفهرس 
Chapter 1: The history of oil wall painting in decoration of Egyptian historical buildingsOnly 14 pages are availabe for public view
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Abstract
Oil wall paintings in the historical churches in Egypt confront major
challenges either by their exposure to uncontrolled environmental conditions
or by incompatible non-professional conservation interventions. Nonprofessional conservators in some of these churches could use inappropriate
materials that finally cause changes in the paint appearance. This cannot be
isolated from the fluctuations of temperature, relative humidity and the
existence of air pollutants in indoor climate which could be increased not
only by the daily use of incense and candles during liturgies but also by air
exchange. In addition to that mechanical stresses are accompanied leading to
loss of cohesion, cracks, flaking and complete losing of paint layers.
The appearance of paintings is considered to be the most important factor that
articulates the artists’ intentions through a unique combination of colors.
Chromatic changes can alter the appearance and perception of the painting.
Nowadays, there is a big interest of conservators and scientists to study the
causes of either chemical or physical changes in the paint appearance, which
may be due to the uncontrolled environmental conditions. Unsuitable
conservation interventions by application of inappropriate materials may also
cause yellowing and significant changes in the painting appearance and
structure. This issue becomes more complicated in the oil paints from the
Renaissance era to the 19th century when the industrial revolution made
available new synthesized pigments. These synthesized pigments are likely
to have the ability to react with the surrounding environment and the
incompatible conservation materials to show discoloration (darkening, fading
or blooming).
In this thesis, Chapter I contains a discussion of the history of oil wall
paintings in Europe and how this fairly modern technique was transferred to the Middle East and Egypt since Mohammed Ali Pasha era. Oil painting
techniques adorned the walls and the ceilings of a number of the historical
royal palaces, mosques and churches with natural, legendary, religious
scenes, geometric decorations and urban panoramas. This chapter also
includes the techniques of oil wall paintings found in the Egyptian historical
examples and how the stratigraphy of these techniques fairly differed from
their traditional ones.
Chapter II includes the chemical properties of the drying oil medium and
pigments through which the chemical reactions of organic medium and/or the
inorganic pigments with either the surrounding uncontrolled environment or
usage of inappropriate conservation materials could be easily expected. This
chapter also includes the mechanisms of chemical and physical changes of oil
paints through which an interpretation of the possible chemical reactions and
change of physical appearance occurred in the drying oils and pigments was
discussed. These reactions could be enhanced by the used painting materials,
manufacturing methods, uncontrolled environmental condition and
incompatible treatments which may finally lead to their degradation.
Chapter III includes the practical and experimental studies that were carried
out to investigate the aspects of physical, chemical and mechanical changes
in oil wall paintings of the selected dome. This chapter includes the
investigation of oil painted dome of Archangel Gabriel church which has
been selected due to its overall darkening in appearance. The study included
the investigation of the dome stratigraphy, the variety of the used drying oil,
pictorial palette, and deterioration products with the aim of assessing its
present state of conservation to finally justify the treatment procedures. Cross
sections, Stereo microscopy, Scanning electron microscopy coupled with the
dispersive energy of X-ray spectrometer, Multi-spectral imaging, Fourier transformed infrared spectroscopy, Gas chromatography-Mass spectroscopy,
X-ray fluorescence, X-ray diffraction, colorimeter, Gas samplers, Data
loggers and the colorimetric measurements were employed for technical
analysis and assessment the present conservation state of the dome. The
investigation of the dome confirmed that the dome was applied with the oil
painting technique on dry plasters. The dome was executed at two different
times as visual investigation, Multi-Spectral imaging and dome flaking
revealed the existence of older paintings under the 1907 paintings. The older
paintings were only found along the outer edges of the dome and have the
same colored motifs of 20th
-century paintings. The original painters of 1907
paintings were well educated by the chemistry of the painting materials as the
analyses confirmed that they mixed linseed oil with highly stable earth
pigments as carbon black, hematite, yellow Ochre, green earth, burnt Sienna
besides using a stabilizer in the pigment mixtures as barite to form the
painted layer. The dome of Archangel Gabriel church was in bad condition
because serious damages mainly occurred in the paint layer were directly
connected with the uncontrolled environmental conditions and nonprofessional conservation interventions occurred since 1994. Fixing the paint
flakes, cleaning of the paint surface, removal of salts and removal of the
over-painted areas of the dome were essential steps to retrieve the aesthetic
and historic values of the dome.
As a part of the research, experimental samples were prepared with the same
stratigraphy of the dome and subjected to thermal and UV artificial aging
with the aim of understanding the deterioration mechanisms of oil wall
paintings and studying the effect of conservation materials with the efficiency
of their applications on the physical appearance. To study the physical and
chemical deterioration aspects of oil paints, a group of common pigments
used during the 19th and 20th were selected and were subjected to UVartificial/natural aging and salt weathering. Microscopy, colorimetric
measurements, and multi-spectral imaging, FTIR, XRD and Raman
Spectroscopy were carried out to diagnose the physical and chemical changes
of paints before and after aging. The experimental study showed that the
chromatic change of the painted layer was mainly affected by either the
oxidation of the binding medium, the reaction of the binder with the pigments
to form metal soaps or by the chemical change of the pigments. The
chromatic change could be visually discernible or easily be recognizable by
the colorimetric measurements.