Raman investigations on marker pen inks

Characterization and conservation of materials used in contemporary art are a big challenge for scientists and restorers because of the huge variability and the large heterogeneity of their use and compositions. The aim of this work is to contribute to the knowledge of the composition of new materials extensively applied in contemporary artworks, namely the marker pen inks. Marker pen inks represent a serious problem for restorers as they fade in a few years, changing colour and shade. Moreover, they are often soluble in the commonly used solvents. This research is performed in collaboration with the Fondazione Federico Fellini, owner of more than 500 original drawings of the famous movie director most of them realised by marker pens. In this work, we report, for the first time, Raman spectra of marker pen original and laboratory drawings. Studies of the laboratory samples have been complemented by thin layer chromatography in order to separate the complex colouring mixture into its individual components. Raman spectra of yellow, orange and red standard samples of two consumer and two professional brands have been recorded and identified. A comparison among old and new marker pen inks composition is discussed, and inferences are drawn about the brand likely used in the two originals. Interestingly, we notice that food additives are often used as colour agents in marker pen inks and report here their standard Raman spectra. This study puts into evidence the need for a reliable standard database of pigments and dyes. Copyright (C) 2012 John Wiley & Sons, Ltd.