Driving Forces of Adhesion Failure between Paint and Cellulose Diacetate in Walt Disney Animation Cels
This research seeks to draw scientific insights from the interplay of processes, which combined lead to the failure of adhesion between paint and cellulose diacetate (CDA), which as a substrate represents the majority of the animation cel collection at Walt Disney Animation Research Library (ARL). In collaboration with a team of conservation researchers at Getty Conservation Institute (GCI), this research has utilized an approach with a rescuer’s mentality, but is thus limited to deaccessioned animation cels, blank interleaving sheets, blank coversheets, or paint mockups pre-approved as samples for experimental research. The scientific value of this manuscript, however, relies on this important material collection in order to ensure representative naturally-aged samples to help evaluate the weakest links of decay in each layer of this laminate, heterogeneous material, that no mockup could ever equal. The interdisciplinary nature of this research is focused between materials science, polymer organic and physical chemistry, mechanical and chemical engineering, and conservation science of plastics and photographic materials, making it possible to delve into fundamental aspects of the chemical mechanisms and physical engineering of these systems from the macro to the nano-scale.
As a compilation of future research papers into chapters, this dissertation overall considers properties that influence the conservation challenge to preserve the paint adhesion to the substrate, so one can continue to interpret the artwork visually. The first chapter includes a multi-analytical case study investigating natural aging properties of cellulose diacetate sheets through the worst case scenarios of the ~80 year old Walt Disney animation cels alongside accelerated aging of blank CDA sheets. By tracking these chemical properties through various visualization methodologies, one can better understand the relevant chemical properties to consider for future storage solutions. The polymer decay is monitored through an improved ion chromatography detection method of percent free acetic acid in a water extract of an improved sample size of 100 mg, published here for the first time [Chapter 2 & 3]. The time-scale of the process of the paint delamination is dependent on the rate of water sorption (usually minutes-hours), where the timescale of the process of plastic failure is dependent on the availability of water to react with the polymer and then the buildup of the acetic acid, which is on the timescale of months at elevated temperatures, or mere decades in hotter climates. Therefore, one chapter also utilized different adhesion methodologies for the purpose of easier quantification of this important property of failure of the different layers of the system [Chapter 4]. Adhesion was measured through the application of interfacial fracture mechanics by laser spallation and through surface nano-mechanical properties through atomic force microscopy (AFM), paired with contact angle measurements and thermodynamic calculations to evaluate standards of polymers with different degree of substitution (DS).
Major contributions of this work forward approaches to quantify the buildup of % free acetic acid, to quantify the interfacial adhesion of the animation cel and the adhesion of paint, and within the final chapter the development of two scientific assays developed for finding and monitoring storage solutions for animation cels. Advanced chemical engineering is paired with paintings conservation to create the sensor in 5.1, and 5.2 utilizes molecular correlations between standards and extracted samples through nondestructive attenuated total reflectance Fourier transform infrared (ATR-FTIR). Efforts presented in this dissertation to identify the driving forces of adhesion in animation cels demonstrate quantitative materials science based structure-property relations relevant to decision-makers of art storage guidelines, in order to engineer practical, prescriptive, and preventive solutions.