Cellulose nitrate objects in collections: history of science and technology hand in hand with conservation of cultural heritage

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Publication . Neves, Artur Louro Mendonça; Melo, Maria João; Friedel, Robert; Callapez, Maria Elvira

Celluloid is a notoriously challenging material for conservation science due to its fast, danger- ous, and complex degradation. The conservation of celluloid heritage continues to be at risk and it is urgent to develop sustainable and efficient preservation strategies. This doctoral pro- ject innovatively addresses this challenge by adopting an interdisciplinary approach combin- ing conservation science with the history of science and technology. By focusing on early in- dustrial formulations and using the first products made with celluloid as case studies, billiard balls and dentures, this project contributes to a new understanding of celluloid’s materiality, historical significance and conservation needs. The history of celluloid billiard balls and celluloid dentures has long remained shrouded in mystery. Historians deemed celluloid billiard balls as an impractical failure. This perception was largely due to a lack of understanding of the billiard balls’ composition. Using a multi- analytical approach to analyze billiard balls from the National Museum of American History (NMAH, Washington, D.C., EUA), it was found that they were made with a bone-cellulose nitrate composite (75%/25% by wt.), patented by John Wesley Hyatt in 1869. By correlating this material information with written sources, the bone-cellulose nitrate composite was found to be consistently employed in celluloid billiard ball production from the 1870s to the 1950s and played a crucial role in bringing the decline of ivory in billiard balls. Similarly, celluloid dentures have been considered a product with limited success and likely insignificant after the 1880s. This study aimed at characterizing the early celluloid-ver- milion (mercury sulfide, HgS) compositions of denture collections from the NMAH and the National Museum of Dentistry, Baltimore, USA. The results of these analysis, combined with source research, revealed an unexpected finding, namely that celluloid remained a significant material in dental prosthetics production up until the 1940s. These findings offer valuable in- sights into the evolution of celluloid billiard balls and dentures manufacture and highlight the importance of continued efforts to identify and understand the various formulations of celluloid, in all its material dimensions, as this knowledge significantly contributes to the con- servation of its cultural heritage. In Portugal, celluloid has entered oblivion since research on early plastics is very scarce. Therefore, a vital objective of this thesis was to contribute to a broader understanding of its historical significance in Portugal. Two comb collections from Casa da Memória de Guimarães and Sociedade Martins Sarmento (Guimarães) were analyzed, revealing the presence of cellu- loid, horn, cellulose acetate, and polystyrene. The results were used, in conjunction with writ- ten and statistical sources, to examine the impact of celluloid on the evolution of the Portu- guese comb industry. The case study of Portugal offers a compelling illustration of the inter- play between horn and celluloid in the shift from traditional industries to modern plastic man- ufacturing sectors. It is now of outmost importance to establish preservation strategies for these collections due to their importance in the history of plastics in Portugal. The experience of analyzing different heritage collection in the USA and Portugal with handheld Raman MIRA DS, demonstrates the efficacy of this technique to characterize cellu- loid and plastics. The device's portability and versatility facilitated in-situ analysis producing high-quality spectra validated through reference comparison and supplemented by μFTIR. This thesis strongly advocates for the broader implementation of handheld Raman spectros- copy in studying plastics heritage. Finally, in response to the need for effective methods to study celluloid degradation, this thesis presents an innovative approach to address this critical research issue. Synchrotron Deep UV multispectral micro luminescence spectroscopy (DUV-PL) was employed for the first time to investigate celluloid heritage, taking advantage of its high sensitivity and spatial resolution. This approach proved essential for detecting early degradation markers and char- acterizing the heterogeneous environments of zinc oxide, which are linked to the manufactur- ing or degradation history. Overall, this thesis shows the considerable potential of DUV-PL for the study of plastics heritage and for the development of innovative methods for its preser- vation.

2023Tese de doutoramento

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Entidade financiadora

Fundação para a Ciência e a Tecnologia

Programa de financiamento

OE

Número da atribuição

PD/BD/136678/2018