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ABSTRACT
A wealth of period literature from as early as 1856 through the 1920s promoted the toning of salted paper prints with platinum to achieve certain aesthetic effects and improve silver image permanence. A variety of toning bath compositions were proposed to achieve a range of image tones. Additionally, other platinum and matte silver photographic processes, such as kallitypes, silver-platinum prints (e.g., “Satista”), and silver-intensified platinum prints, were popular during the salted paper print revival and may have similar characteristics. However, few examples of prints containing both silver and platinum have been identified in museum collections. To investigate their chemical natures and range of appearances, the authors fabricated prints according to historic recipes. These simulacra were analyzed by XRF spectroscopy and color measurement and artificially aged to provide data relating to metal content, appearance, and longevity. High-resolution electron microscopy of the salted paper print samples revealed the chemical influence of the toning method on the metallic nanostructures that comprise the image. Ultimately, the analytical results are tied to visual observations to elucidate toning methods used by early photographers, contribute to process identification, and draw conclusions about the conservation of these materials.
RÉSUMÉ
Dès 1856 et jusqu'à la fin des années 1920, une abondante littérature a fait la promotion des tirages sur papier salé virés au platine pour obtenir certains effets esthétiques et améliorer la stabilité de l'image argentique. Une variété de compositions de bains de coloration était proposée pour produire une palette de tonalités. De plus, d'autres procédés photographiques au platine et à l'argent mat comme les kallitypes, les tirages argent-platine (p. ex. Satista) et les épreuves au platine intensifiées à l'argent étaient populaires durant le renouveau des tirages sur papier salé et peuvent avoir des caractéristiques similaires. Cependant, peu d'exemples d'épreuves contenant à la fois de l'argent et du platine ont été identifiés dans les collections muséales. Pour étudier leur nature chimique et l'éventail de leur apparence, les auteurs ont produit des tirages en se basant sur les recettes anciennes. Ces imitations ont été analysées par spectroscopie de fluorescence par rayons X et par mesure de couleur, et vieillies artificiellement pour fournir des données relatives au contenu métallique, à l'apparence et à la longévité. La microscopie électronique à haute résolution des échantillons d'épreuves sur papier salé a révélé l'influence chimique de la méthode de virage sur les nanostructures métalliques qui composent l'image. Finalement, les résultats d'analyse sont couplés à des observations visuelles pour éclaircir les méthodes de virage utilisées par les premiers photographes, pour contribuer à l'identification des procédés, et pour tirer des conclusions au sujet de la conservation de ces matériaux. Traduit par Mireille Brulotte et Isabelle Cloutier.
RESUMO
Uma vasta literatura do período a partir de 1856 até a década de 1920 promoveu a viragem de impressões em papel salgado com sais de platina para obter certos efeitos estéticos e melhorar a permanência da imagem de prata. Para atingir uma variação nos tons da imagem, foram propostas diversas composições para os banhos de viragem. Adicionalmente, outros processos fotográficos de superfície fosca de prata e processos de platina, tais como calitipias (kallitypes), impressões de prata e platina (por exemplo, Satista) e impressões de platina intensificadas pela prata, eram populares durante o renascimento das impressões em papel salgado e podem ter características semelhantes. No entanto, poucos exemplos de impressões contendo prata e platina foram identificados em coleções de museus. Para investigar suas naturezas químicas e variedade de aparências, os autores fabricaram impressões de acordo com receitas históricas. Estes simulacros foram analisados por espectroscopia de XRF e medição de cor e envelhecidos artificialmente para fornecer dados relativos ao conteúdo de metal, aparência e longevidade. A microscopia eletrônica de alta resolução das amostras de impressão em papel salgado revelou a influência química do método de viragem nas nanoestruturas metálicas que compõem a imagem. Em última análise, os resultados analíticos estão ligados a observações visuais para elucidar os métodos de viragem usados pelos primeiros fotógrafos, contribuir para a identificação de processos fotográficos e tirar conclusões sobre a conservação desses materiais. Traduzido por Millard Schisler.
RESUMEN
Una gran cantidad de literatura de la época desde 1856 hasta la década de 1920 promovió la técnica de virar las impresiones de papel salado con platino para lograr ciertos efectos estéticos y mejorar la permanencia de la imagen de plata. Se propusieron una variedad de composiciones de baño para virar para así lograr una gama de tonos de imagen. Además, otros procesos fotográficos de platino y plata mate, como kallitipos, impresiones de plata y platino (ej. “Satista”), e impresiones de platino intensificado con plata, fueron populares durante el renacimiento de la impresión en papel salado y pueden tener características similares. Sin embargo, se han identificado pocos ejemplos de impresiones que contengan plata y platino en las colecciones de museos. Para investigar su naturaleza química y variedad de apariencias, los autores fabricaron impresiones de acuerdo con recetas históricas. Estos simulacros se analizaron mediante espectroscopia XRF y medición de color y se envejecieron artificialmente para proporcionar datos relacionados con el contenido de metal, el aspecto y la longevidad. La microscopía electrónica de alta resolución de las muestras de impresiones de papel salado, revelaron la influencia química del método para virar en las nano estructuras metálicas que componen la imagen. En última instancia, los resultados analíticos están vinculados a las observaciones visuales para dilucidar los métodos de tonificación utilizados por los primeros fotógrafos, contribuir a la identificación del proceso y extraer conclusiones sobre la conservación de estos materiales. Traducción: Andrea Venosa; revisión: Fernanda Valverde y Amparo Rueda.
Acknowledgements
Sample preparation and imaging using FIB-SEM and HRTEM was performed at the National Institute of Standards and Technology by Dr Alline Myers (Center for Nanoscale Science and Technology) and Dr Keana Scott (Materials Measurement Division).
Disclosure statement
No potential conflict of interest was reported by the authors.
Notes on contributors
Joan M. Walker received a PhD in Inorganic Chemistry in 2015 from Indiana University, where her research focused on the interaction between metallic nanoparticles and proteins under visible light excitation. After a brief internship in the Conservation Science Department at the Indianapolis Museum of Art, she was hired as a Conservation Scientist at the National Gallery of Art. Funded by The Andrew W. Mellon Foundation, her current research activities aim to gain a better material understanding of the creation and preservation of photographs from the early photographic era. Her interest in conservation dates back to her undergraduate career at Washington University in St. Louis (BA, summa cum laude, Chemistry and Art History) and subsequent position as conservation technician at the Indiana Historical Society. Address: National Gallery of Art, 2000B South Club Drive, Landover, MD 20785; [email protected].
Ronel Namde is a Photograph Conservator at the National Gallery of Art in Washington, DC. She graduated from the Winterthur/University of Delaware Program in Art Conservation in 2015 with a specialization in photographic materials. She received her BA in Anthropology from Yale University in 2007 and worked at the Yale Library for five years as a conservation technician. Her work there involved both the general and special collections, including materials from the Beinecke Rare Book & Manuscript Library. She did her third-year internship at the Weissman Preservation Center after completing summer internships at the Arab Image Foundation in Beirut, Lebanon, and the United States Holocaust Memorial Museum. At the National Gallery, she has been able to work on upcoming exhibition, loans, and collections maintenance, and participate in ongoing research on platinum and palladium photography thanks to a grant from The Andrew W. Mellon Foundation. Address: as for Walker.
