Results from the first phase of the Organic Materials in Wall Paintings (OMWP) project were presented at a daylong symposium in May 2006 at the new Centro di Conservazione e Restauro La Venaria Reale near Turin, Italy. In attendance were experts from the field of wall paintings conservation, including art historians, architects, conservators, and conservation scientists.
The OMWP project is a partnership among the GCI and a number of scientific laboratories whose goal is to develop a set of guidelines to facilitate the study of organic materials in wall paintings. The project has two parts: first, to evaluate various investigation techniques and develop a series of guidelines for organic materials identification, and second, to apply these guidelines to wall paintings conservation case studies in order to illustrate the guidelines and their practical benefits.
At the symposium, each of the OMWP partner teams presented results from its method of analysis and showed the extent of the method's ability to detect organic materials in the wall paintings replicas tested. The evaluation of the techniques was based on the level of information obtained and the accuracy of this information against the known composition of the replicas. Four levels of information were considered: presence, class, type, and mixture of organic materials. Not all of the analytical techniques provided information at each level.
This first phase of work has shown that the study of organic materials in wall paintings must include an understanding of the paintings' inorganic pigments, since these affect the results of some of the techniques being tested. For example, noninvasive methods such as UV fluorescence photography or fiber optic fluorescence spectroscopy (FOFS) may show the presence and location of fluorescent material but may not distinguish between different types of organic binders, and the absorption of fluorescence by pigments can give a false negative result—the absence of fluorescence does not mean absence of organic material.
Results presented at the symposium confirmed that invasive analytical methods, such as gas chromatography and immunological testing (for the extremely specific identification of proteins), provided the highest level of information and accuracy. However, within the advocated methodology, noninvasive investigations remain essential to the preliminary study of the painted surface in order to point out sample locations representative of other areas in the painting.
Testing samples of known composition allowed for improved interpretation of the results provided by each technique. This was especially important for new methods. Results from these investigations will be made available in a reference database.
The second phase of the OMWP project will apply information gathered in the first phase to the study of mural paintings currently under restoration. All studies will be carried out in close collaboration with conservators.
For further information on the OMWP project, visit the Getty Web site.