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tumacacori Analysis

Polychromy
Laboratory analysis is currently ongoing in order to investigate and identify original finish stratigraphies.
Tumacacori’s primary façade was originally finished in a polychromatic  painted lime plaster where significant decorative finishes can be found on the entrance, arch, columns, and moldings. Currently approximately 155 square feet of historic plaster is estimated to remain on the exterior; however, repair plasters may be obscuring a great deal more of the original fabric. Generally, the historic plasters are two to three layers thick and contain remnants of red, yellow, orange, and blue- black colored finishes. Stratigraphic analysis reveals that the plaster layers consist of a rough-cast or scratch coat with a brown or intermediate coat (in some areas up to 0.25 inch thick) and a thin limewash  approximately 0.5-1mm thick.

Samples collected have been analyzed using cross-sectional analysis, various methods of microscopy, X-ray diffraction (XRD), scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM-EDS), and Fourier transform infrared spectroscopy. These various analytical methods yield a range of stratigraphic, topographic, molecular, and elemental information that will characterize the original and subsequent surface finishes and their current conditions.
crosss section
Above:  A cross-section of the same sample at 100x magnification  shows a sandy substrate with a white preparatory layer and thin red pigmented finish.
Right:  Examining samples under a stereomicroscope
analysis-1
A photomicrograph of red pigment sample analyzed with reflected light microscopy prior to embedding and cross-sectioning  
microscopy