Investigation Techniques for Identifying Organic Materials
The project component was conducted in two phases: assessment of a group of investigation techniques on wall painting replica samples and application of the results of the assessments to ongoing conservation projects.
Conservation Scientist Giancarlo Lanterna (Opificio delle Pietre Dure - OPD) and Conservator Mark Gittins (Head of Lippi conservation team, Conservazione Beni Culturali) examining and evaluating results of invasive investigations on site. The OPD, one of the OMWP partners, has been responsible for the diagnostic investigation for this project, which included the characterization of the synthetic resins used during previous conservation interventions.
Over the past twenty years, the Conservation Institute has developed an expertise using invasive techniques such as infrared spectroscopy, gas chromatography, and mass spectroscopy for the identification of organic materials in easel paintings. Based on this expertise and on the expertise of the project partners, the Institute developed the Organic Materials in Wall Paintings project, joining the interest of several conservation and scientific institutions with expertise in noninvasive and invasive technologies to identify organic materials in wall paintings.
Background Research and Evaluation
To aid future study and to improve conservation treatments, historical and analytical information on organic materials in wall paintings was collected and tabulated. The historical literature was reviewed, looking at types of materials and their preparation methods as described in manuscripts, treatises, and manuals. A review of the analytical literature was carried out to determine which types of organic materials have been identified, while recording the analytical techniques used for this purpose. This bibliographic research was published in Reviews in Conservation, 2004, pp. 6380.
To evaluate investigation techniques, the project focused on a set of wall painting replicas made by Leonetto Tintori that had been prepared with different types of binders and pigments applied on lime-based plasters. The investigation methodology was grouped by technique type—invasive or noninvasive. For wall paintings, noninvasive technologies must be portable, available for use often high up on scaffolding. To that end, the project evaluated a variety of available portable techniques for organic materials identification. The evaluation was carried out to assess both the accuracy of the results and the level of information provided by each technique.
Application of the Methodology
The application of the methodology in case studies helped to illustrate the methodological approach and can be used to highlight the implications of the presence of organic materials in wall paintings conservation as well as the ways this information can be used by conservators to develop their intervention and to plan the monitoring of conditions.
One of the most significant outcomes of this project is related to the noninvasive investigations and the assessment of the capacity and limitation of each investigation technique tested, particularly for new portable methods. Another valuable contribution was bringing scientists onsite to work side by side with conservators to address conservation issues.