Sensor detects deterioration in art works

Equipment measures physicochemical changes to materials in cultural objects caused by environmental conditions of museums

By Elton Alisson

Agência FAPESP – The climatic and environmental conditions of museums and other closed spaces may affect the works of arts in their collections.

To evaluate possible damage to cultural heritage pieces caused by the environmental characteristics of these spaces, researchers from the Universidade de São Paulo (USP) have developed a sensor that indicates the level of degradation of the materials in art works in different environments.

The equipment, which has undergone many improvements, is the result of a research project funded by FAPESP through its Young Researchers in Emerging Centers Program.

During the study, researchers from the USP School of Arts, Sciences and Humanities (EACH) East Campus developed a tool that made it possible to simultaneously measure temperature, humidity, illumination and pollution levels inside museums in urban areas, as well as the level of deterioration over time of the organic resins used in art works. The researchers from EACH collaborated with a research group from the USP Chemistry Institute, led by Professor Dalva Lúcia Araújo de Faria.

Combining knowledge of analytical chemistry with the electronics and micro-processing skills of one of the post-doctoral students in the group (Carlos Antonio Neves), the researchers were able to create a miniature device that automatically measures physicochemical changes caused by the environmental conditions in museums in some organic materials in these art works .

“The equipment shows a set of effects on the organic materials in some art works caused by the temperature, humidity, illumination and pollutants in an environment,” USP professor and project coordinator Andrea Cavicchioli told Agência FAPESP.

The sensor is based on a quartz micro-scale composed of small quartz crystals, approximately one centimeter in diameter, that vibrate at high frequencies (10 MHz).

To analyze the physicochemical alterations to a particular material that may occur in a specific environment, a thin layer of the material is placed over the quartz crystals and then placed in the environment to be monitored.

The quartz crystals capture the transformations in the material as variations in frequency that are registered and recorded in the unit’s electronic memory system.

“The faster the frequency changes, the faster the material will be degrading, indicating that the environment is very aggressive,” explained Cavicchioli.

The researchers used a type of varnish frequently present in art works to test the equipment inside two São Paulo museums, the University of São Paulo Museu Paulista (better known as the Museu do Ipiranga) and the São Paulo State Pinacoteca. The study was performed in conjunction with teams led by curators Teresa Cristina Toledo de Paula and Valéria Mendonça.

After leaving the equipment with the varnish sample in both locations for a predetermined period of time, the group found that the Museu Paulista, in comparison with the Pinacoteca, had less favorable conditions for the conservation of the materials used in paintings.

Cavicchioli says that the difference is due to the Museu Paulista’s difficulty in implementing adequate conditions for the conservation of cultural objects because the building itself has been declared an official monument.

“Even though the Museum is fully aware that environmental controls are necessary for the protection of cultural objects, the Museu Paulista’s physical spaces are still not well adapted due to the fact that the building itself is a cultural object. The Pinacoteca has undergone more transformation and was readjusted to implement some mitigating measures, such as the installation of air conditioning, air filters for external pollutants and light control equipment,” Cavicchioli explained.

The Museu Paulista is currently undergoing environmental adaptation, funded by FAPESP under its Museum Infrastructure Program, to improve the conditions for conserving its collection. According to Cavicchioli, following this adaptation process, a new evaluation will be conducted with the sensor to verify whether the remodel improved the institution’s micro-environmental conditions.

Baroque churches

The researchers, together with organist Elisa Freixo, also evaluated the micro-environmental conditions in two baroque churches in the state of Minas Gerais: Catedral da Sé in Mariana and the Igreja Matriz in Tiradentes. The churches are home to two of the most important restored and functional pipe organs from the Baroque period in Brazil.

The organ pipes, which are made of lead, corrode easily in the presence of certain gases released by the wood of which the instrument is made, other wood in the environment or the mixture of the lead with other metals.

By analyzing the emissions from the wood and the composition of the pipes, the researchers found that neither the wood in the organ itself nor the environment inside the church presented a significant risk to the conservation of the organ pipes because the old wood releases less gas than newer wood does. Furthermore, the organ pipes contain tin, which protects the metal from corrosion.

“We evaluated that there are no immediate dangers to these organs due to release of gas from the wood or composition of the lead. In a tropical place like Brazil, there are much greater risks to the conservation of these musical instruments, such as termite attacks,” Cavicchioli said.

Through a doctoral research project funded by an FAPESP scholarship, the group intends to expand its scope and compare the micro-environmental conditions for the conservation of ecclesiastical objects in churches built in the 18th and 19th centuries in urban, semi-urban and coastal regions.

In another research project funded by FAPESP through a cooperative agreement with the Conselho de Defesa do Patrimônio Histórico, Arqueológico, Artístico e Turístico (The Historical, Archaeological, Artistic and Touristic Heritage Defense Council, or CONDEPHAAT, part of the São Paulo State Secretariat of Culture), the group intends to evaluate the vulnerabilities of cultural objects to climatic variations in the Vale Histórico Paulista (Paulista Historical Valley).

The region, situated at the far eastern end of São Paulo state along the borders of Minas Gerais and Rio de Janeiro states, was Brazil’s wealthiest region during the Ciclo do Café (Coffee Cycle) and still boasts colonial homes and small palaces.

“We want to analyze the ways in which climate changes will affect the cultural objects and what type of preventive policies can be implemented to protect this historical and cultural heritage, something that is much discussed in other countries, such as those in Europe,” Cavicchioli affirmed.