The disastrous copper. Comparing extraction and chelation treatments to face the threat of copper-containing inks on cellulose

Zaccaron, Sara; Potthast, Antje; Henniges, Ute; Draxler, Johannes; Prohaska, Thomas; McGuiggan, Patricia

doi:10.1016/j.carbpol.2018.10.075

Cited by 6 publications

(6 citation statements)

References 18 publications

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“…The deleterious effects of copper-containing species with paper have been the focus of attention for paper conservators and heritage conservation scientists alike; however, in contrast to our research, the research has been heavily focused on treatment development and evaluation. 4,8,44,48,49 While there are several established chemical structures for Cu(II) acetates or verdigris, the present study documented that two starting species (basic and neutral) will transform into a different verdigris species, the intermediate Cu(CH 3 COO) 2 • 3Cu(OH) 2 •2H 2 O during their degradation, as pigment, and in the presence of cellulose. This species has been documented previously, but the impact of other common constituent documents (gum arabic) has not been well-documented.…”

Section: Resultsmentioning

confidence: 54%

Multi-Analytical Study of Copper-Based Historic Pigments and their Alteration Products

et al. 2019

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Copper-containing materials such as verdigris are commonly found in historic and artistic works of art, often at advanced states of decay. Applied on paper as inks and watercolors, many of which needed a binder such as gum arabic, the intrinsic instability of this pigment was known since the medieval period. The decay of verdigris (a mixture of copper acetates) as a pigment, as watercolor, and as a dye, was studied using a combination of vibrational (Fourier transform infrared) and X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD) instrumental techniques. Changes in the copper oxidative states and the formation of copper oxide were monitored during accelerated degradation as powdered solids and applied on mockup samples (with and without binder). Accelerated aging of both commercially available and synthesized verdigris pigments showed the presence of an intermediate species, Cu(CH3COO)2•3Cu(OH)2•2H2O, which points to the beginning of the decay processes, that culminates in the formation of Cu(II) oxide. However, the presence of gum arabic seems to delay deterioration, by temporarily reducing Cu(II) to Cu(I), even when the final product includes Cu(II). This novel application of XPS and supporting techniques has significant implications in art conservation, as the identified behavior helps explain the better preservation state of some works of art.

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Section: Resultsmentioning

confidence: 54%

Multi-Analytical Study of Copper-Based Historic Pigments and their Alteration Products

et al. 2019

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“…Although its physical meaning might be debatable, a parabolic model has already been used to describe the degradation mechanism of various polymers. ,, In our specific case, the different mathematic models applied may find an explanation in a combination of the extent of oxidation and the specific mode in which the two oxidants modify the cellulose. As for the latter, it is worth remembering that H 2 O 2 –Fe ions primarily generate carbonyl groups, while hypochlorite also leads to carboxyls (COOH) in addition to aldehydes (CHO) and ketones.…”

Section: Resultsmentioning

confidence: 99%

How Alkaline Solvents in Viscosity Measurements Affect Data for Oxidatively Damaged Celluloses: Cupri-Ethylenediamine

et al. 2019

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Although efficient and inexpensive, conventional viscometry to determine the average degree of polymerization (DP) of cellulose may mislead the final DP because cellulose degradation occurs in the used solvents, which consist of alkaline amino complexes of transition metals, such as cupri-ethylenediamine (CED). For oxidatively damaged pulps or celluloses, viscosity-DP determinations may be more inaccurate because alkali-induced β-elimination reactions render such oxidized celluloses even more vulnerable. Despite the risk identified in many studies, a systematic investigation of the parameters affecting the viscosity-DP assessed by reliable analytics is still required. Here, a new approach evaluating the effects of CED on oxidized cellulosics was used (i.e., immediate pulp regeneration after dissolution in CED). In-depth molecular feature characterization (e.g., absolute molar masses and oxidized groups’ profiling related to molecular weight distribution) by gel permeation chromatography coupled with fluorescence and multiangle laser light scattering clarified the behavior of oxidized celluloses and the influencing parameters upon dissolution in CED.

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“…To address this problem, Zaccaron et al compared CaPhy treatment with a new method using glucose as a reducing sugar, which based on the Fehling reaction, would selectively remove free copper ions by precipitating them as an insoluble cuprous oxide in the treatment bath [71]. However, this glucose treatment caused severe hydrolytic and oxidative degradation with remarkable yellowing on the paper and is not a viable conservation option.…”

Section: Pos-phytate Treatmentsmentioning

confidence: 99%

Iron-gall inks: a review of their degradation mechanisms and conservation treatments

et al. 2022

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Iron-gall inks are an essential element of our written cultural heritage that is at risk of a total loss due to degradation. This degradation leads to the loss of the support, particularly the cellulose-based support. Intending to stabilize it, we have come a long way from the nineteenth-century cellulose nitrate laminations to the relatively recent phytate treatments; nevertheless, less invasive treatments are needed. To pave the way for developing safer and more sustainable treatments, tailored as much as possible to the object, this paper reviews the conservation treatments and the advances that have taken place over the last decade in our understanding of the degradation mechanisms of iron-gall inks, based on a careful selection of references to support a concise microreview. This discussion is based on the currently accepted models based on the Fe3+-gallate and the identification of degradation products for iron-gall inks observed in heritage objects, including manuscripts dating from the fourteenth to seventeenth centuries and drawings from the fifteenth to nineteenth centuries. The degradation promoted by iron-gall inks induces scission of cellulose through acid catalysis and/or redox reactions. The causes of these acid-base and redox reactions are also assessed. Finally, we detail the state-of-the-art conservation treatments used to mitigate iron gall ink deterioration, covering treatments from the late nineteenth century to the beginning of the twentieth century, followed by the presentation of current phytate treatments and new postphytate treatments.

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The disastrous copper. Comparing extraction and chelation treatments to face the threat of copper-containing inks on cellulose

Cited by 6 publications

References 18 publications

Multi-Analytical Study of Copper-Based Historic Pigments and their Alteration Products

Multi-Analytical Study of Copper-Based Historic Pigments and their Alteration Products

How Alkaline Solvents in Viscosity Measurements Affect Data for Oxidatively Damaged Celluloses: Cupri-Ethylenediamine

Iron-gall inks: a review of their degradation mechanisms and conservation treatments

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