Chemistry and cultural heritage
|Leonardo da Vinci, The Last Supper, about 1495/98|
Milan, Our Lady of Grace
This most famous painting has big conservation problems
Cultural heritage is the complex of
monuments and artifacts of historical, technical, cultural and artistic value, that make
up the legacy of the past and document the evolution of countries and nations.
Cultural heritage must be maintained and conveyed to the
next generations, so it can be enjoyed in the present and in the future. Cultural goods
are subject to degradation, mainly through chemical
transformations. The role of chemistry is understanting, preventing, controlling and
Chemistry and its techniques, therefore, are deeply involved
with cultural heritage.
Rome, Saint Peter in Chains
Chemistry of sculpture
Sculpture is the art of
making statues and other works of art from hard materials such as stones and metals. The
chemical constitution and properties of such materials determine the characteristics of
the final work, the way of processing, and the effect of aging.
Sculptors have always been concerned with the features of
their materials, though they often didn't understand the chemical basis for such features.
Nowadays chemistry is actively involved in materials selection, in dictating rules for
handling, and in caring conservation. The last issue is especially important for ancient
Chemistry of paintings
Painting is based on colors, and
colors are the result of
interaction between light and chemical substances. When a painter chooses his colors, he
is actually selecting what chemical substances
he will lay on his table (or wall, or whatever). Slightly different hues may be due to
completely different chemical formulas.
Colors are not stable. Chemical reactions can make dyes
disappear, or turn to different colors. New colors can be formed from the painting
materials, or added by deposition, for instance of
It is a great challenge for chemists to prevent or slow down
such changes. Conservation techniques include exclusion from the contact with air,
temperature and humidity control, removal of dirty layers.
Protection of cultural
|Highly degraded ancient books|
Cultural goods, like all objects, have a definite chemical
composition and chemical reactivity. They are not, therefore, in a stable state but are
subject to continuous change, mostly due to environmental
factors and human action.
Protecting the artifacts and alleviating the negative effects
of such factors is a critical task for chemistry.
Chemical literacy for conservation
|Cleaning the tympanum of the portal of Seville Cathedral,
Left, before and Right, after
Knowledge of the chemical
nature (composition, structure,
properties, reactivity) and of the physical properties of the materials constituting
cultural artifacts, as well as their source and way of processing, are the prerequisite
for conservation and restoration.
Tasks belonging to chemistry in the conservation and
restoration of cultural heritage include:
- Knowledge of the factors affecting the
|Restoration of Holbein's painting The Ambassador, London,
National Gallery, 1553|
a) The restored painting; b), c), d) During the restoration several methods of
instrumental chemical analysis have been employed
- Evaluation of the state of the artifacts and of the ongoing processes
- Setup of suitable procedures for cleaning, strenghtening and protecting cultural
- Evaluation of effectivenes of the treatment and its duration in
analytical techniques and sophisticated equipment are available to accomplish such