“MRI and Unilateral NMR study of reindeer skin tanning processes” by Zhu et al (2015)

Zhu, Lizheng; Del Federico, Eleonora; Ilott, Andrew J.; Klokkernes, Torunn; Kehlet, Cindie; Jerschow, Alexej, “MRI and Unilateral NMR study of reindeer skin tanning processes”, Analytical Chemistry 87(7) (2015) 3820–3825.

DOI:10.1021/ac504474e (ACS Publications, restricted access)

Abstract:

The study of arctic or subarctic indigenous skin clothing material, known for its design and ability to keep the body warm, provides information about the tanning materials and techniques. The study also provides clues about the culture that created it, since tanning processes are often specific to certain indigenous groups. Untreated skin samples and samples treated with willow (Salix sp) bark extract and cod liver oil are compared in this study using both MRI and unilateral NMR techniques. The two types of samples show different proton spatial distributions and different relaxation times, which may also provide information about the tanning technique and aging behavior.

“Use of aluminium alkoxide and oxazolidine II to treat acid-deteriorated historic leather” by Lama et al (2015)

Lama, Anne; Antunes, A. Paula M.; Covington, Anthony D.; Guthrie-Strachan, Jeffry; Fletcher, Yvette;“Use of aluminium alkoxide and oxazolidine II to treat acid-deteriorated historic leather”, Journal of the Institute of Conservation 38(2) (2015) 172–187.

DOI:10.1080/19455224.2015.1071713 (Taylor& Francis Online, restricted access)

Abstract:

This study was undertaken to develop a product that will potentially delay the progress of deterioration of acid-deteriorated historic leather. Acid-deteriorated leather samples were treated with a new formulation consisting of aluminium di(isopropoxide) acetoacetate ester chelate (aluminium alkoxide) and 5-ethyl-1-aza-3,7-dioxabicyclo[3.3.0]octane (oxazolidine II). The leather samples were also treated with oxazolidine II and aluminium alkoxide separately to compare the effectiveness of these reagents against the new formulation. Untreated leather samples were used as a negative control. Acid-deteriorated leather samples treated with Cellugel®, aluminium alkoxide and the new formulation along with corresponding untreated leather samples were also subjected to accelerated ageing in order to investigate the longevity of the treated leather. The impact of the treatments and accelerated ageing was determined by measuring the hydrothermal stability of the leather and pH of the aqueous extract. The formulation showed a potential to provide the acid-deteriorated historic leather with long-term protection against an artificially-created acidic environment.

Resumé:

Cette étude a été menée afin de développer un produit pouvant potentiellement retarder la progression de la détérioration du cuir ancien devenu acide. Des échantillons de cuirs acides ont été traités avec une nouvelle formule composée de chélate d'aluminium d'acétoacétate de di-isopropoxyde (alcoolate d'aluminium) et de 5-éthyl-1-aza-3,7-dioxabicyclo [3.3.0] octane (oxazolidine II). Les échantillons de cuir ont également été traités avec, séparément, de l'oxazolidine II et de l'alcoolate d'aluminium pour comparer l'efficacité de ces réactifs par rapport à la nouvelle formule. Des échantillons de cuirs non traités ont été utilisés comme témoin négatif. Des échantillons de cuirs dégradés par l'acidité traités avec du Cellugel®, de l'alcoolate d'aluminium et la nouvelle formule ainsi que des échantillons correspondant aux mêmes cuirs non traités ont été également soumis au vieillissement accéléré afin d'étudier la longévité du cuir traité. L'impact des traitements et le vieillissement accéléré ont été évalués par une mesure de la résistance du cuir à la chaleur et du pH de l'extrait aqueux. La formule a montré une capacité à fournir au cuir ancien acide une protection de long terme face à un environnement acide artificiel.

“Thermal characterization of new, artificially aged and historical leather and parchment” by Sebestyén et al (2015)

Sebestyén, Zoltán; Czégény, Zsuzsanna; Badea, Elena; Carsote, Cristina; Şendrea, Claudiu; Barta-Rajnai, Eszter; Bozi, János; Miu, Lucretia; Jakab, Emma; “Thermal characterization of new, artificially aged and historical leather and parchment”, Journal of Analytical and Applied Pyrolysis 115 (2015) pp.419–427.
DOI:10.1016/j.jaap.2015.08.022 (ScienceDirect, restricted access)

Abstract:

The aging mechanism of leather and parchment was studied by thermoanalytical methods to understand the effect of the environment on the historical manuscripts and the heritage of libraries and archives. Alkaline and acidic treatments followed by thermal dehydration were applied to achieve chemical changes in the structure of new leather and parchment similar to the slow natural aging of historical samples. Chemical and structural changes during both natural and artificial aging processes were characterized by thermoanalytical techniques. The thermal stability and the evolution profile of the decomposition products under slow heating were studied by thermogravimetry/mass spectrometry (TG/MS). The distribution of the decomposition products of these collagen-based materials under fast pyrolysis was characterized by pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS). It was found that the maximal rate of the thermal decomposition (DTGmax) significantly decreases by aging in case of both leather and parchment samples indicating the degree of deterioration. Py-GC/MS has been found to be a suitable technique to sensitively monitor the degradation of the polyphenolic components of the vegetable tannins under natural or artificial aging. It was established that the tannin content of leather is more significantly affected by natural aging and alkaline treatment than the main structure of the polypeptide chains. Principal component analysis (PCA) has been used to find statistical correlations between the experimental data for leather samples. The results of the PCA confirmed that the alkaline treatment and the natural aging processes similarly modify the tannin content of the vegetable tanned leather.

Writing box with painted and gilded leather, c.1525, Victoria & Albert Museum