Revealing time's secrets at the National Theatre of Costa Rica: innovative software for cultural heritage research

TL;DR

This paper introduces innovative multispectral imaging software tools for non-invasive analysis of large-format paintings, enabling detailed study of materials, artist's techniques, and conservation status, exemplified by Italian artworks in Costa Rica.

Contribution

The development of two novel software tools, RegionOfInterest and CrystalDistribution, advances non-invasive analysis of cultural heritage paintings, facilitating detailed material and conservation studies.

Findings

Identified the artist's main color palette including zinc white, lead white, and others.

Mapped pigment crystal sizes to distinguish natural from artificial pigments.

Confirmed paint stratigraphy using microscopy and spectroscopy.

Abstract

Establishing affordable, efficient, accessible, innovative, and multidisciplinary methodologies are key to the creation of modern public policies on cultural heritage. Limited access to large-format paintings is a challenge to restoration scientists seeking to obtain information quickly, in a non-invasive manner, and identify regions of interest. Therefore, we put forward two unique software tools based on multispectral imaging techniques, with the long-term aim of assessing the artist's intentions, creative process, and color palette. This development paves the way for a comprehensive and multidisciplinary understanding of the mysteries encompassed in each pictorial layer, through the study of their physical and chemical characteristics. We conducted the first-ever study on Musas I and II, two large-format paintings by Italian artist Carlo Ferrario, located in the National Theatre of Costa Rica. In this study, we used our novel techniques to chose regions of interest in order to study sample layers; while also assessing the works' state of conservation and possible biodeterioration. We explored the applications of our two versatile software tools, RegionOfInterest and CrystalDistribution, and confirmed paint stratigraphies by means of microscopy and spectroscopy analyses. In a pilot study, we identified the artist's main color palette: zinc white, lead white, chrome yellow, lead read, viridian, along with artificial vermilion and ultramarine pigments. We were able to identify artificial vermilion and ultramarine and distinguish them from the natural pigments using CrystalDistribution to map the average size and diameter of the pigment crystals within the paint layers. This study demonstrated that software-based multidisciplinary imaging techniques are fundamental in establishing preventive and non-invasive methods for historical painting conservation studies and virtual restoration.