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Communication Dans Un Congrès Année : 2022

Study of a chemical treatment based on zinc salts for ancient glass objects sensitive to atmospheric degradation in museums

Résumé

Depending on their composition and conditions of conservation, a significant part of glass objects of the Cultural Heritage (CH) preserved in a museum-like atmosphere since their manufacture show signs of chemical and physical damages, initially induced by moisture attack [1]. Until now the best protective measure applied by conservators and curators to slow down this active degradation is the control of the environment (temperature (T), relative humidity (RH), pollutants) within suitable museum display cases. In the view of developing more efficient and less costly protective methods, we have investigated the potentiality of a chemical surface treatment based on zinc salts. Zinc salts are indeed known to protect freshly manufactured float glasses against atmospheric alteration in an industrial context. To this purpose, a deposit protocol in accordance with the museum context was carried out on relevant ancient glass composition replicas (alkali (Na,K)–rich silicate). By the mean of accelerated ageing experiments (temperature and relative humidity control) on both untreated or treated glass replicas, the evolution of the glass surface and sub-surface was studied at all scales with complementary tools and the Zn (II) speciation was characterized by GI XAS. A positive and striking effect of the zinc salt treatment to reduce the replica glasses hydration kinetics has been shown with ageing experiments at 80°C and 40°C [2]. From our experimental results, several hypotheses regarding the origin of the Zn(II) protective action were drawn. In particular, we put in evidence the formation of a chemisorbed Zn(II) species on the glass surface and its progressive insertion in the glass sub-surface during the alteration. These zinc species seem to have a predominant role in the protection mechanisms and have been shown to be thermally activated [3]. Therefore, a zinc salt treatment might be considered if a moderated heating step of the glass surface is accepted. However, the treatment performances seem to be strongly dependent on the surface alteration degree before the deposit. This is a decisive point as regards the relevance of the treatment for the glass artwork conservation, which should be investigated deeper. [1] O. Majérus et al., npj Mat. Deg., 4, 2020, 36. [2] F. Alloteau et al., J. Am. Chem. Soc., 104, 2021, 2039-2051. [3] F. Alloteau et al., J. Am. Chem. Soc., 104, 2021, 2052-2065.

Domaines

Chimie
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Dates et versions

hal-04196508 , version 1 (05-09-2023)

Identifiants

  • HAL Id : hal-04196508 , version 1

Citer

Fanny Alloteau, Valentina Valbi, Odile Majérus, Isabelle Biron, Daniel Caurant, et al.. Study of a chemical treatment based on zinc salts for ancient glass objects sensitive to atmospheric degradation in museums. International Congress on Glass (ICG) 2022, Jul 2022, Berlin, Germany. ⟨hal-04196508⟩
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