Introduction

The analytical investigation carried out in the framework of the PURPLE project was conducted to provide the most comprehensive characterization of the codices, both concerning technological and conservative issues.

Although invasive methodologies represent a fundamental tool for an in-depth study of a complex object such as a work of art, the increasing development and the optimization of non-invasive techniques lead to a widespread use in the field of Cultural Heritage.

Because of the high historical and artistic relevance of the objects under study, an extensive and non-invasive analytical investigation was thus preferred in order to preserve the integrity of the manuscript by avoiding any sampling activities. The non-invasive investigation allowed providing a wide spectrum of information on:

• Support (parchment or paper)
• Purple dyes for tinting the parchment (orchil, folium and other organic dyes)
• Pigments and dyes (for the illuminated areas)
• Inks
• Metallic pigments

Among the non-invasive analyses, imaging and spot spectroscopic techniques have been selected for the PURPLE project.