Plastiques et patrimoines

Introduites depuis une centaine d’années par l’industrie, les matières plastiques ont été largement utilisées pour produire des objets de la vie quotidienne et des œuvres d’art qui font aujourd’hui partie des collections patrimoniales. Malheureusement certains de ces matériaux se dégradent trop rapidement et les connaissances en matière de conservation et de restauration sont encore balbutiantes. La prise de conscience récente de l’importance des enjeux pour le patrimoine du xxe siècle a été le point de départ du programme de recherche européen POPART (Preservation Of Plastic ARTefacts in museum collections) financé par la Commission européenne dans le 7e programme cadre de recherche et de développement et coordonné par le CNRS. Les résultats de ces travaux sont articulés autour de quatre thèmes : l’identification des matières plastiques constitutives des objets patrimoniaux, l’analyse et les constats d’état des collections, l’étude de la dégradation des plastiques et les traitements de conservation. Ils s’adressent aux conservateurs, restaurateurs, scientifiques du patrimoine et étudiants intéressés par les aspects techniques de la conservation de ces collections.Introduced about a hundred years ago by industry, plastics have been widely used to produce everyday objects and artworks that today belong to cultural heritage collections. Unfortunately, some of these materials have deteriorated too rapidly and our knowledge about their conservation and restoration is still in its infancy. The growing awareness of the importance of the risks for 20th-century cultural heritage was the starting point for the European research project POPART (Preservation Of Plastic ARTefacts in museum collections), part funded by the European Commission within the framework of the seventh research and development programme coordinated by the CNRS. The results of this study hinge on four main themes: the identification of plastic objects in museum collections, the analysis and condition of the collections, the study of the degradation of plastic artefacts and conservation techniques. This research is intended for curators, restorers, cultural heritage scientists and students interested in the technical aspects of conserving these collections

Contributions to the Characterization of Chromogenic Dyes in Color Slides

Funding: This research was supported by Fundação para a Ciência e Tecnologia, Ministério da Ciência, Tecnologia e Ensino Superior (FCT/MCTES), Portugal, through doctoral program CORES-PD/00253/2012, PhD grant SFRH/BD/52317/2013, and Associate Laboratory for Green Chemistry-LAQV financed by national funds (UIDB/50006/2020 and UIDP/50006/2020). This work was also funded through RNEM (Portuguese Mass Spectrometry Network) (LISBOA-01-0145-FEDER-022125–IST).Chromogenic reversal films (or color slides) are first-generation positive transparencies. These were used for various purposes, namely as an artistic medium, especially from the 1960s onwards. However, these materials are intrinsically vulnerable to chemical degradation and have poor long-term stability. Although over time significant improvements have been achieved in the stability of chromogenic products, chromogenic dyes are highly susceptible to oxidation and hydrolysis, both induced by light and/or relative humidity and temperature, leading to the fading and shift in the original color balance of the images. During the present investigation, a gap of knowledge regarding chromogenic materials in general, and chromogenic reversal films specifically, was detected. Today, there is still no methodology to identify the dyes present in a specific work and, therefore, to study their chemical mechanism of degradation. From this premise and focused on case studies from the Portuguese artist Ângelo de Sousa (1938–2011), a research study was carried out seeking the characterization of chromogenic dyes. Based on the isolation of the different dyes composing a chromogenic material, several procedures were tested to describe the dyes found in chromogenic reversal films, such as Raman spectroscopy, thin-layer chromatography (TLC), infrared spectroscopy, high-performance liquid chromatography with diode array detector (HPLC-DAD) and coupled with mass spectrometry (HPLC-HRMS). Promising results were achieved with this approach, opening new paths for the understanding of these materials.publishersversionpublishe

A study of the relationship between the migration of image silver and perceived yellowing of silver gelatine photographs

Silver gelatine photographs were the most dominant photographic process of the twentieth century from the 1880s until the 1960s. They are prone to yellowing, mirroring and fading which is largely attributed to the effects of pollutants, relative humidity and residual processing chemicals. Experts in the conservation of photographs claim they can determine the causes of deterioration with the naked eye: the effects of humidity result in a more yellowed appearance, whilst the presence of residual chemicals results in a redder appearance. This work aims to investigate if the same deterioration processes can be diagnosed in photographic prints with a spectrophotometer by addressing two questions: (1) In new and artificially aged silver gelatine photographs is it possible to distinguish between discolouration caused by silver migration and that caused by the presence of residual sulfur? (2) What are the complexities of applying these findings to historic photographs? A set of test photographs, some well processed and some insufficiently washed was developed and artificially aged. These were compared to a small collection of historical photographs of different ages, paper types and image colours. Samples were assessed using visual observation, residual silver and hypo spot tests, colour measurements including L*a*b* and reflectance spectra, Fourier transform infra-red (FTIR) spectroscopy and transmission electron microscopy (TEM). After artificial ageing the well processed test photographs were more yellowed, TEM indicated that this was due to colloidal silver formation. The insufficiently washed test photographs were more red but also darker, TEM showed these samples to have more homogeneous silver filaments, thought to be due to silver sulfide formation. The results for the historical photographs were similar but more subtle. A larger sample set is needed to investigate this more extensively. Further investigation on historical samples, with colour measurements and residual silver and fixer spot tests will take place

Effets du nettoyage et du conditionnement sur la dégradation des PVC plastifiés

Le polychlorure de vinyle plastifié est un polymère synthétique, largement utilisé depuis le milieu du xxe siècle et jusqu’à nos jours, pour la production d’œuvres d’art et d’objets. Son état de conservation est souvent médiocre en raison de la migration des plastifiants. L’étude de l’impact du nettoyage et du mode de conditionnement de PVC vieillis naturellement en environnement muséal sur leur évolution permet d’envisager des conditions de conservation préventives et curatives optimales afin d’en limiter les dégradations.Plasticized polyvinyl chloride is a synthetic polymer, widely used from the mid-20th century until today in the production of artworks and artefacts. Its condition is often mediocre owing to the migration of plasticizers. The study of the impact of cleaning and conditioning on the evolution of naturally ageing PVCs in a museum environment has enabled us to envisage optimum conditions for preventive conservation so as to mitigate the degradation process

Conservação da coleção de álbuns fotográficos do Museu da Imagem e do Som de Goiás

This paper discusses the conservation of a collection of photographic albums belonging to the Goiás Image and Sound Museum, which was carried out with Vitae Foundation funding and in partnership with Funarte's Center for Photographic Conservation and Preservation. The authors present a brief description of each photographic album along with historical data and information about their state of deterioration, as well as the procedures adopted and the main interventions performed during their conservation.O artigo tem como objeto o tratamento de conservação da coleção de álbuns fotográficos do Museu da Imagem e do Som de Goiás, realizado com recursos provenientes da Fundação Vitae, em parceria com o Centro de Conservação e Preservação Fotográfica da Funarte. Apresentamos, com referência a cada álbum fotográfico, informações históricas, uma descrição sumária, as características de deterioração, os procedimentos adotados e as principais intervenções realizadas durante o tratamento de conservação

La conservazione preventiva del patrimonio librario come possibile alternativa al restauro tradizionale

The present paper focuses on the close relation between library collections and their preservation environment, aiming, in particular, at highlighting the importance of promoting and sustaining the monitoring. The paper proposes some simple and ready-to-use technologies – smart monitoring – to prevent future damages

Peindre avec la lumière. Entre art et science, les prémices de la photographie couleurs au XIX e siècle

International audienceAu XIX e siècle, les scientifiques investissent le champ de la photographie pour appréhender la lumière et, chemin faisant, ils inventent la photographie couleur. Si dès 1848 Edmond Becquerel réussit à fixer, sur du chlorure d'argent, les couleurs du spectre solaire décomposé par un prisme, Gabriel Lippmann introduit en 1891 une solution élégante et pérenne avec un procédé interférentiel de photographie couleur. Cette invention illustre de façon incontestable la théorie posée par Augustin Fresnel et satisfait la communauté scientifique, toutefois elle ne connaît quasiment pas d'application en photographie. C'est finalement l'usage d'un réseau coloré trichrome présenté par le physicien John Joly qui est adopté par l'industrie photographique à la fin du XIX e siècle. Il est popularisé, au début du XX e siècle, avec les plaques autochromes des frères Lumière puis éclipsé par l'apparition des films couleurs chromogènes en 1935. Cette présentation retrace le cheminement des travaux-entre le laboratoire du scientifique et celui du photographe-qui ont mis la photographie couleur à la portée des photographes amateurs et professionels