Conservation of the stone in Cibeles Fountain, Madrid , Spain

Abstract

The water in Cibeles Fountain flows in a closed circuit and is replaced every 6 months. After this period of time, an increase in bicarbonate, sulfate, calcium and magnesium contents is registered in the water, as well as a slight increase in its acidity. This acidity, favored by atmospheric pollution, is the main cause for the process of dissolution that marble used in the ornamental sections of the fountain undergoes. Calcite-based marble, from the Carrara quarries in Italy, of the cherubs suffers the most acute dissolution processes, while dolomite-based marble, used for the main sculpture body is less affected by these processes. Dissolved materials fall on certain sections of the sculpture and of the fountain forming dirt crusts and inlaid soiling. In order to prevent decay of the fountain building materials, periodical control of water composition is necessary, with a view to stabilizing water pH level at around 7.8. It is likewise necessary to add chemicals that prevent bacteria and algae proliferation, thus improving water quality.