FWF Project No. L187-N11The innovative application of the advanced analytical techniques GC-MS, Py-GC-MS, and FTIR-microscopy for the investigation of organic coatings on metal museum objects
Co-workers: Dr. Václav PITTHARD, DI Sabine STANEK, Mag. Helene HANZER (Collection of Sculpture and Decorative Arts), Dr. Claudia KRYZA-GERSCH (Collection of Sculpture and Decorative Arts), in cooperation with the University of Applied Arts Vienna, Institute for Restoration and Conservation Within a former research project (FWF, project no. P15640-N03) a gas chromatography-mass spectrometry (GC-MS) system was installed at the Conservation Science Department of the KHM for the investigation of complex natural binding media systems in historic works of art. Also a database of natural polymers for GC-MS and Pyrolysis-GC-MS investigations was built-up. Also in scope of the project was the verification and improvement of the experimental methods to be applied for the analysis of unique and valuable works of art. Within the ongoing project these improved sample preparation and analyses methods for (Py)-GC-MS, the connected databases and a set of about 9,000 unaltered and artificially aged reference samples will be available for the investigation of organic coatings on metal based museum and indoor objects. A set of 650 Renaissance and Baroque bronze sculptures, held in the Collection of Sculpture and Decorative Arts of the KHM will be studied with respect to their organic coatings. These coatings contain original “patinas” by tinted organic lacquers – applied by the artists themselves – as well as conservation lacquers – applied later to prevent the objects from corrosion or to influence their aesthetic appearance. A systematic study of the coatings and therefore state of the objects’ surfaces has never been done before and is needed for art historical research as well as for the development of conservation concepts to preserve these unique and valuable objects in the best possible way. In addition, the organic coatings present on the sarcophagi-ensemble within the Imperial Crypt in the church of the Capuchin Friars (the Kapuzinergruft), Vienna will be studied. The tin-lead alloy sarcophagi were originally covered with organic coatings based on shellac and dyes after 1790. Due to the high relative humidity within the Imperial Crypt the sarcophagi developed severe corrosion and were therefore treated by several restoration campaigns from 1964 up to 2002 applying epoxy resin based, nitrocellulose and/or acrylic based lacquers, respectively. A survey performed by the Institute for Restoration and Conservation of the University of Applied Arts in 2002-2003 revealed severe corrosion mainly where the recent restoration coatings had been applied. To allow for a well-advised conservation and preservation of the sarcophagi the investigation of the chemical changes within the multi-layered coating systems as well as their influence on the metal surfaces is necessary to be performed at first.