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Chemistry and Art

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 repairing such transformations.

Chemistry and its techniques, therefore, are deeply involved with cultural heritage.

Michelangelo, Moses
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 sculptures.

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 smokes.

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 heritage

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, Spain
Left, before and Right, after the treatment

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 degradation
  • 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 goods
  • Evaluation of effectivenes of the treatment and its duration in time

Many powerful analytical techniques and sophisticated equipment are available to accomplish such tasks.