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Summary
This thesis deals with the treatment and conservation
methods of Coptic icons. It consists of the following Studies:
1-Introduction on Coptic Art
Coptic art was introduced in Egypt
since the introduction of Christianity in Egypt. It is an art that was
influenced by several factors and had it is own features. The artistic features
that preceded the Coptic icons are discussed. Also the demolition of Coptic
icons, the most famous Coptic artists and the main subjects painted on the icons
are dealt with.
2-Different kinds of icons and their preparation
Icons vary in
materials and methods of preparation, especially the wooden or linen supports
and the various ground layers such as calcium carbonate "Chalk" or calcium
sulphate hydrate 'gypsum" or kaolinite or zinc or other painting grounds.
Adhesives and binding media were also numerous and differed in their methods of
preparation. They were mainly used to bind the previously mentioned fillers. The
main adhesives or binding media were animal glue, fish glue, gelatin, rabbit
glue, albumin, casein, etc...
Also, the various painting techniques, e.g:
Tempra (egg - white, gum Arabic, animal glue), encaustic painting and oil
painting were discussed.
3-The different colourants used on icons
The most important
colourants that were used for colouring the icons were discussed. Colouring
theories and properties of colourants such as refractive index, coverage,
particle size, specific gravity and relative density are mentioned. In addition
to that, the groups of natural mineral colours and organic dyes are dealt with,
e.g.:
**White colourants: gypsum, zinc, titanium.
**Red colourants: red
ochre, kermes
**Yellow colourants: yellow ochre, osfor
**Blue colourants:
Egyptian blue, indigo. and other colourants such as: violet; brown and black.
4-Deterioration Factors of Icons:
The physical deterioration
factors that affect the wooden support, the gesso layer and the colour layer are
the change of relative humidity in the environment around the icon. The
different layers contract and expand according to the changes. As a result the
icon may deteriorate.
In addition to that an increase on relative humidity
encourages biological attack. Heat, which is another physical factor causes
embrittlement and weakening of the wooden support, the gesso layer and the
binding media (animal glue), as a result the surface of the icon and the wooden
support deteriorate.
Light, another physical factor, causes fading or
weakening of colourants. The chemical deterioration factors, which decay the
support layers for the colourants, are sulphur oxide, ozone, nitrogen oxides,
gases, etc.....
Insects and fungi are the major biological deterioration
factors, that attack icons under certain conditions.
Last, but not least,
man-made deterioration factors are a major problem. They could be due to
destruction on purpose, touching the icon as a blessing or incorrect restoration
within the Egyptian church.
5-Investigation and Analysis of an Icon.
The importance of using
modern scientific methods, for investigating and analyzing the ground layer or
colour layer, is considered.
I.R., U.V. and X.ray radiography are sources
used to reveal the condensed layers which are not evident to the naked eye,
cracks or previous restoration.
I.R. and U.V. spectroscopy are used to
identify the binding media in the ground layer or colour layer.
Scanning
electron microscopy is used to study the deterioration forms of all the layers
of an icon.
6- Methods of Treatment and Conservation of Icons.
There are
various methods and materials that can be used for cleaning wax, soot or fly
secretions from an icon's surface. Also, old and new varnish layers may be
cleaned or removed when blooming occurs. In cases where cracks, pitting or
separation of the icons layers are evident treatments may be applied. In some
cases, where the wooden support is badly deteriorated, the linen support with
all the drawings may be removed. After that the wood may be completely treated
and consolidated.
Another point of treating Coptic icons is the retouching or
repainting of colours and the use of new varnishes after cleaning an icon, in
order to retain its ol glamour.
The last step of treating an icon in a museum
or church is to exhibit it under suitable conditions.
7-Practical Part
The various methods for preparing an icon
according to the old techniques were applied by the researcher. These new icons
were artificially aged and treated. Therefore, it was possible to choose the
most suitable treatment for ancient icons, before application.
Several
painting grounds were prepared, according to different references. These grounds
were then coloured by using organic or mineral colours. They were all placed in
a drying oven at high temperature and high humidity, as a means of artificial
ageing.