Background: Saccharide materials have been used for centuries as binding media, to paint, write and illuminate manuscripts and to apply metallic leaf decorations. Although the technical literature often reports on the use of plant gums as binders, actually several other saccharide materials can be encountered in paint samples, not only as major binders, but also as additives. In the literature, there are a variety of analytical procedures that utilize GC-MS to characterize saccharide materials in paint samples, however the chromatographic profiles are often extremely different and it is impossible to compare them and reliably identify the paint binder. Results: This paper presents a comparison between two different analytical procedures based on GC-MS for the analysis of saccharide materials in works-of-art. The research presented here evaluates the influence of the analytical procedure used, and how it impacts the sugar profiles obtained from the analysis of paint samples that contain saccharide materials. The procedures have been developed, optimised and systematically used to characterise plant gums at the Getty Conservation Institute in Los Angeles, USA (GCI) and the Department of Chemistry and Industrial Chemistry of the University of Pisa, Italy (DCCI). The main steps of the analytical procedures and their optimisation are discussed. Conclusions: The results presented highlight that the two methods give comparable sugar profiles, whether the samples analysed are simple raw materials, pigmented and unpigmented paint replicas, or paint samples collected from hundreds of centuries old polychrome art objects. A common database of sugar profiles of reference materials commonly found in paint samples was thus compiled. The database presents data also from those materials that only contain a minor saccharide fraction. This database highlights how many sources of saccharides can be found in a paint sample, representing an important step forward in the problem of identifying polysaccharide binders in paint samples.

This article presents results from a binding media survey of 61 Romano-Egyptian paintings. Most of the paintings (51) are the better-known funerary mummy portraits created using either encaustic or tempera paint medium. Samples from all the paintings (on wooden panels or linen shrouds) were analyzed with gas chromatography/mass spectrometry (GC/MS) to identify waxes, fatty acids, resins, oils, and proteins in one sample. Analytical protocols that utilized three separate derivatization techniques were developed. The first analysis identified free fatty acids, waxes, and fatty acid soaps, the second characterized oils and plant resins, and the third identified proteins. The identification of plant gums required a separate sample. Results showed that fatty acids in beeswax were present as lead soaps and dicarboxylic fatty acids in some samples was consistent with an oxidized oil. The tempera portraits were found to contain predominantly animal glue, revising the belief that egg was the primary binder used for ancient paintings. Degraded egg coatings were found on several portraits, as well as consolidation treatments using paraffin wax and animal glue. The unknown restoration history of the portraits caused uncertainty during interpretation of the findings and made the identification of ancient paint binders problematic. Also, deterioration of the wooden support, residues from mummification, biodegradation, beeswax alteration, metal soap formation, and environmental conditions before and after burial further complicated the analysis. The inherent problems encountered while characterizing ancient organic media in funerary portraits were addressed. The fourteen museums that participated in this study are members of APPEAR (Ancient Panel Paintings: Examination, Analysis, and Research), an international collaborative initiative at the J. Paul Getty Museum whose aim is to expand our understanding of ancient panel paintings through the examination of the materials and techniques used for their manufacture.

Cellulose diacetate and cellulose triacetate cels from animated feature films in the collection of the Walt Disney Animation Research Library were tested by several analytical techniques in order to assess their composition and look for evidence of degradation. Triphenyl phosphate and a range of phthalate plasticizers were identified using pyrolysis-gas chromatography/mass spectrometry, which also showed evidence that evaporation of more volatile plasticizers may have occurred. Plasticizer content measurements by solvent extraction, found to be more accurate than volatile content data from thermogravimetric analysis, revealed there was less residual plasticizer in triacetate cels compared to diacetate cels. Gas chromatography/mass spectrometry, performed to quantify the acetyl content of cels after removal of plasticizers by solvent extraction, revealed some evidence for hydrolysis of the oldest cels, although the reduction could be related to original variations in acetate content from the polymer manufacturers. Use of Fourier-transform infrared spectroscopy to measure deacetylation of the cellulose acetate polymer based on the hydroxyl to carbonyl peak area ratio proved less satisfactory. Moreover, because the cels cannot be measured directly due to interference from plasticizers, non-invasive assessment of deacetylation using a portable instrument would be impossible. The results from this analytical survey provide an important point of reference against which long-term changes in cel composition can be monitored

Since 2004, scientific research on the damaged Giant Buddha statues and Buddhist paintings in Bamiyan, Afghanistan, has been conducted at various laboratories and large-scale facilities using mass-spectrometry techniques (GC-MS, LC-MS, LC-MS/MS, nano-LC/ESI-MS/MS), ELISA, and synchrotron-based micro-analyses) in parallel to conservation intervention. Studies on samples from these cultural heritage objects have shown that each is composed of a polychromatic multilayered structure with sizing layers, ground layers, painted layers, and glaze. The carefully produced complex multilayered structures were examined using optical microscopy (visible and UV light) as well as synchrotron-based infrared microscopy, both of which revealed various organic and inorganic components in each layer. High sensitivity bulk MS and ELISA methods were used to further identify details regarding organic materials, such as fatty acids and collagens, and these results suggest different vegetable oils and animal species of glues. For example, cow milk casein and cow skin glue were identified in the Eastern Giant Buddha, suggesting that casein was used as a sizing agent and the cow skin glue as a binder for painting. The wall paintings from Cave N(a) (mid-7th century AD) were found to have horse glue used as sizing and drying oil (poppyseed/walnuts/perilla oils) as a binding media. The paintings’ complex structures and their organic and inorganic materials were fully understood using both imaging and bulk methods, and thus, these methods help to reconstruct historical wall painting techniques in full.

The presented research examines 17th century distemper paint from the polychrome wooden interiors of two Norwegian stave churches: Eidsborg and Heddal. For the first time, the inorganic and organic components of specimens from Eidsborg and Heddal were identified using X-ray Diffraction (XRD), Environmental Scanning Electron Microscopy (ESEM)—Energy Dispersive X-ray Spectroscopy (EDS), Fourier-Transform Infrared (FT-IR) spectroscopy, Enzyme-Linked Immunosorbent Assay (ELISA), and Gas Chromatography-Mass Spectrometry (GC-MS) after derivatization. This multi-analytical approach allowed for the identification of red ochre as the main red pigment within the topcoat (with the possible addition of minium), confirmed that a chalk basecoat was used, and finally permitted the recognition of alteration phases. Markers of proteinaceous material attributed to the use of animal-based glues were detected throughout the stratigraphic layers of both churches, with the addition of linseed oil in some locations. Furthermore, the wood substrate showed markers characteristic of pine tree, with contamination of wood fractions being detected in some of the paint samples from Heddal and Eidsborg. This research has contributed to a better understanding of the current preservation state of Heddal and Eidsborg, and ultimately assisted in developing a deeper comprehension and awareness of materials used in Norwegian stave churches.