AIC's 46th Annual Meeting

Traditional conservation techniques first uncovered the existence of Spanish colonial era frescoes on the interior walls of the Sacristy, in the Alamo Church, eighteen years ago. The stencil designs discovered encompass the entire room; at wainscot level, frieze band above entry doors, and along the arches of walls. The universal conservation lab techniques and analysis provided some of the answers however, there is still much to learn about the wall art in the Sacristy. Recently, conservation work in the Sacristy began and more evident questions arose; one inquiry: Is there another way of analyzing the pigment without removal? The answer is to this question is yes, by utilizing traditional analysis and state of the art technology. Through the use of a portable X-ray fluorescence spectroscopy (pXRF), the pigments that remained on the walls in the Sacristy were sampled and characteristic elements were identified. The 2000 paint analysis report identified four Spanish colonial tinted limewashes. The recent utilization of the pXRF analysis report, identified three unknown Spanish colonial tinted limewashes and metal leaf with high levels of copper. In addition to the pXRF, a scanning electron microscope, SEM with EDS capabilities was also used on selected sampled fragments. Elemental maps confirm the identification of vermillion (HgS). This advanced technology helps guide conservation efforts and leaves the microscopic historic elements intact. A second inquiry transpired: How do we visually see the invisible design elements? By employing multi-spectral imaging with ultraviolet florescence technical photography, 3-D photographic techniques: Reflectance Transformational Imaging (RTI) and DSLR photogrammetry were also a part of this project. The multi-spectral imaging documented invisible design elements, important application techniques; “pouncing”, “outlining”, and “block filling”. The multi-spectral imaging created high-resolution images along with 3-D models and photo mosaics. A third inquiry loomed: Why the sophisticated equipment used did not determine the shapes of areas where high levels of Lead (Pb) exist at the “tips” of an invisible floral design? The floral designs are located symmetrically on the original walls. The invisible floral designs contain an urn painted with ochre, reds and copper green. The shape of the urn is unknown. The project utilizing multi-spectral imaging and portable X-ray fluorescence spectroscopy results were exciting, but some of the unknown Spanish colonial designs remain a mystery. Is there a technology that can solve the mysteries in the Sacristy at the Alamo?