A Brief Insight into the Secrets of the 120-Year-Old Main Curtain of the National Theatre of Costa Rica through Non-Destructive Characterization Techniques

Abstract

This article features the preliminary characterization of thirty different-colored samples. The scrutinized fragments were taken from the 120-year-old main curtain from the National Theater of Costa Rica. Results from scanning electron microscopy (SEM) shed light on the textiles used, evidencing the presence of cotton in the reinforcement fabric and linen in the curtain itself. The infrared spectroscopy technique (FTIR) conveys information on the binders used, egg yolk in this case. The elemental composition of the studied pieces was identified using X-ray fluorescence (XRF) spectroscopy technique. Among the most common elements obtained are Zn, Ti, Ca and Ba. Samples which were green or red contained Cu or Cd and Se, respectively. Brown samples present marked signals of Fe. These findings point toward the use of materials such as verdigris, malachite, Scheele green, Cadmium red and Iron oxides as possible pigments within the palette of the curtain. The results obtained through these techniques are supported by a principal component analysis (PCA) and cluster analysis, confirming the presence of three color groups and the existence of mixtures of pigments within the samples. This article delves into the world of stage curtains, from a technical, scientific and historical point of view.