Citation: Izzo, F.C.; Van Keulen, H.; Carrieri, A. Assessing the Condition of Complex Poly-Material Artworks by Py-GC-MS: The Study of Cellulose Acetate-Based Animation Cels. Separations 2022, 9, 131. https:// doi.org/10.3390/separations9050131 Academic Editor: Sara Cunha Received: 26 April 2022 Accepted: 19 May 2022 Published: 23 May 2022 Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affil- iations. Copyright: © 2022 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/). separations Article Assessing the Condition of Complex Poly-Material Artworks by Py-GC-MS: The Study of Cellulose Acetate-Based Animation Cels Francesca Caterina Izzo 1 , Henk Van Keulen 2, * and Alessandra Carrieri 3 1 Department of Environmental Sciences, Informatics and Statistics, Ca’ Foscari University of Venice, Via Torino 155/b, 30172 Venice, Italy; fra.izzo@unive.it 2 Cultural Heritage Agency of the Netherlands (RCE), Hobbemastraat 22, 1070 KA Amsterdam, The Netherlands 3 Italian Ministry of Culture, Conservator officer of Centro di Restauro (Li Punti, SS), Soprintendenza of Sassari and Nuoro, 07100 Sassari, Italy; alessandra.carrieri@beniculturali.it * Correspondence: henkvankeulen@ziggo.nl Abstract: The material composition of a group of Rodovetri, hand-painted animation cels, made in the 1950s and 1960s for Italian television, has been determined by Flash Py-GC-MS, Thermally assisted Hydrolysis and Methylation-(Py-)GC-MS and GC-MS investigations, where, for the pyrolysis applications, the pyrolyzer is connected septum-less to the GC inlet. The condition of the selected animation cels was generally poor (yellowing, exudation, warping, cracking). The cels are made of plasticized cellulose acetate (CA) and decorated with alkyd paint. Exudating plasticizers from the CA support migrated into the paint; this has softened the paint layers and made the cels stick together. CA is known to be very unstable and easily subjected to degradation, which cannot be reversed, only slowed down by preventive conservation. Most of the cels are plasticized with bis(2-methoxyethyl) phthalate (DMEP) and triphenyl phosphate (TPP). The research shows a relationship between the degradation of CA and the presence of TPP and DMEP. Keywords: pyrolysis; GC-MS; cellulose acetate; animation cels; Rodovetri; alkyd paints; ESCAPE 1. Introduction Carosello was the most important advertising space shown on Italian television from 1957 to 1977. These animation drawings were created by Gamma Film and Cinestabilimento Fratelli Donato, two major studios of film production and animation of the 20th century, active in Milan from the late 1930s to the 1980s. In particular, Gamma film, founded by the Gavioli Brothers, was an important growth point for many young Italian designers and talents. The Gavioli Brothers have chosen to keep and store all this material and, later, to entrust all to the Micheletti Foundation and the Musil-Museum of Industry and Labor, located in Brescia (Italy). In the Musil Collection, more than 700,000 Rodovetri are now conserved [1]. The Rodovetri are transparent plastic sheets on which the animator painted the single frame of the animated sequence of a cartoon. Usually, the inkers transferred the lines of the initial paper drawing on the recto of the cel, and then the painters painted on the verso; only the finishes or the corrections were painted using colors on the front of the cel. The transparent surface allowed for creating the character to animate by applying multiple overlapping layers. The cels were then photographed on the motion picture film; each cel corresponds to a “position” of the animation of the character. For each second of animation, at least 12 frames were used to create the illusion of movement. Their use ended after the photo was taken; sometimes, the painted character/image was erased to reuse the transparent sheet. This is to say that the archiving and the conservation of the animated cels over time has never been considered as a crucial point: the cels were simply stored in cardboard boxes, superimposing one on top of the other, sometimes interspersed with Separations 2022, 9, 131. https://doi.org/10.3390/separations9050131 https://www.mdpi.com/journal/separations