Search

In recent decades, computed tomography (CT) combined with suitable image processing software has become a valuable tool to enable the reading of texts written on scrolls, which are fragile, damaged, or fused together, without physically unwrapping them. X-ray based computer tomography has successfully been used on scrolls made of soft materials such as papyrus and parchment. Although in few cases inscriptions on thin metal plates that have been rolled up and worn as amulets have been deciphered by using a high energy X-ray source, the readability of writings on of metal scrolls is limited by the high attenuation factor of this type of material. In this paper, we present for the first time the use of neutron tomography as an alternative to X-ray tomography for studying hidden inscriptions on folded metal objects. It is shown that the method overcomes the limitations of X-ray tomography caused by high attenuation of X-rays in lead objects. The inscription on the medieval Bispegata amulet, unearthed during excavations in Oslo's Old Town, has been read by using neutron tomography combined with VG Studio software. The amulet was made up of a thin lead sheet with an inscribed text, folded together into a rectangle. The inscription was runic, containing words of religious and magic meaning.

The Oseberg ship is one of the most important archaeological testimonies of the Vikings. After excavation in 1904, the wooden gravegoods were conserved using alum salts. This resulted in extreme degradation of a number of the objects a hundred years later through acid depolymerisation of cellulose and lignin. The fragile condition of the artefacts requires a reconsolidation which has to be done avoiding water as solvent. We synthesized tert-butyldimethylsilyl (TBDMS) chitosan which is soluble in a 50:50 solution of ethyl acetate and toluene. Measurement of its molecular weight, to anticipate its penetration, provided a challenge as the density difference of the polymer and solvent was too small to provide adequate solute redistribution under a centrifugal field, so a two-stage process was implemented (i) determination of the weight-average molar mass of the aqueous soluble activated precursor, chitosan mesylate, Mw,mc using sedimentation equilibrium with the SEDFIT-MSTAR algorithm, and determination of the degree of polymerisation DP; (ii) measurement of the average degree of substitution DSTBDMS of the TBDMS group on each chitosan monosaccharide monomer unit using NMR, to augment the Mw,mc value to give the molar mass of the TBDMS-chitosan. For the preparation, we find Mw = 9.8 kg·mol−1, which is within the acceptable limit for penetration and consolidation of degraded wood. Future work will test this on archaeological wood from different sources.

This work is part of a larger study, which aims to use soda lignin from straw as the starting point for a non-aqueous consolidant for highly degraded archaeological wood from the Oseberg collection. This wood was treated with alum salts in the early 1900s, is actively degrading and exists in varying states of preservation. Non-aqueous consolidants are an option to stabilize this wood mechanically in cases where it is too deteriorated to undergo aqueous-based retreatments, for example using polyethylene glycol. The aim of this study was to compare the extent of penetration of two soda lignin preparations in low- to medium-degraded archaeological pine. The soda lignins were dissolved in ethyl acetate and had two molecular weight groups: P1000 (molecular weight Mw of~3 kDa) and the ethyl acetate fraction FB01 (Mw of ~1 kDa). Penetration after immersion was evaluated by infrared spectroscopy and analytical pyrolysis. Treated specimens were also evaluated using weight and dimensional change and scanning electron microscopy. Both lignins penetrated into sample cores, but P1000 did not penetrate as well as FB01. This may be due to differences in their molecular weights, but also differences in polarity due to the presence of different functional groups.

Samples of conserved archaeological wood of different ages, origins, and conservation histories were aged in a climate chamber for seven months, while the humidity alternated between 30% RH for 12 hours and 80% RH for 12 hours at a constant temperature of 30°C. Photographs were taken once every hour, which enabled the creation of a time-lapse movie. Some samples degraded visibly, whereas others were unaffected. Most of the samples were robust and would be able to survive well even in a very poor museum climate. Among the sensitive samples, three types of degradation were identified, namely disintegration, pyrite oxidation, and efflorescence of white crystals. Disintegration was ascribed to dimensional changes caused by the RH alternations in very fragile wood. The white efflorescence was interpreted as the recrystallization of an alum-associated substance, possibly mercallite (KHSO4). The pyrite oxidation was observed as the efflorescence of a thick yellow, grey, and green powder. Characterization of selected samples was performed using X-ray fluorescence spectrometry, X-ray diffraction spectrometry, scanning electron microscopy with energy dispersive X-ray spectroscopy, inductively coupled plasma – optical emission spectroscopy, Fourier transform infrared spectroscopy, ionic conductivity – liquid chromatography, and pyrolysis-gas chromatography-mass spectrometry with in situ silylation using hexamethyldisilazane.

Vibrational spectroscopy is widely used in the study of pigments and degradation processes in historical art objects. Bis(acetato-κ2O,O) diammine copper(II) [Cu(MeCOO)2(NH3)2] shares coordination features with some types of copper soaps found in paint layers containing the green pigment Verdigris. In this study, we present new insights based on observed vibrational (IR, Raman) spectra. The Raman spectrum is presented for the first time, while only very early IR data were previously available. The interpretations are supported by quantum chemical calculations. The model calculations for a dimeric cluster model show the importance of including at least two metal complex units and an extended hydrogen-bond network to properly simulate the crystal environment. Decent agreement with experimental spectra was achieved applying a DFT-level layered integrated molecular orbital model.

The Oseberg collection includes the most complete ensemble of wooden remains from the Viking Age. However, since many of the wooden objects were treated with alum in the early 1900s, they now suffer from dramatic conservation issues. A multi-analytical approach was adopted to investigate both the organic and the inorganic components of some selected wood fragments, with the aim of fully characterising the materials and their decomposition products. A particular focus was taken on the differences between the surface and the core of the fragments analysed, and on the correlations between the results obtained by the different techniques, in order to disclose possible interactions between the materials during degradation. In addition to differences in alum concentration and wood alteration between the surface and the core, some decomposition/transformation products of alum, such as mercallite (KHSO 4 ), were identified by FTIR and XRD. Contextual interpretation of the results obtained by ICP-OES elemental analysis of inorganic components and Py(HMDS)-GC/MS characterisation of degraded lignocellulosic materials supported some previous observations about potential relationships between specific metals (Al, Fe, Ca) and wood degradation and enabled new correlations to be highlighted. Although similar degradation patterns were revealed in the investigated objects–depletion of holocellulose, oxidation of lignin and some transformation of alum - a notable variability at the molecular level was highlighted. This is an important factor to be taken into account for the planning of re-treatment strategies of these extremely precious artefacts.

The 6-deoxy-6-aminocelluloses—or “aminocelluloses”—are a class of synthetic natural cellulose derivatives which are mostly aqueous soluble and have excellent film-forming properties. Recent studies have connected these properties at the molecular level with protein-like self-associative behaviour for a range of aminocelluloses including a 6-deoxy-6-(ω-aminoethyl) aminocellulose AEA-1 with the association being a two-stage process—a reversible oligomerisation followed by further (semi-reversible) aggregation into larger structures. Here, we synthesise and compare a new 6-deoxy-6-(ω-aminoethyl) aminocellulose AEA-1′ with different degree of substitution with one with further alkyl derivatisation, namely 6-deoxy-6-(ω-hydroxyethyl) aminocellulose HEA-1′. As with AEA-1, sedimentation velocity and sedimentation equilibrium in the analytical ultracentrifuge still show a two-stage process for both AEA-1′ and HEA-1′, with the latter giving higher molar masses. The consequences of these properties for use as consolidants for archaeological wood are considered.

Green pigments in micro-samples taken from three late-medieval painted objects from Norwegian churches have been investigated with the aim to characterize their constituents and understand how they relate to damages observed in passages containing green paints. The cross-sections were analyzed by optical microscopy under visible and UV light, Scanning Electron Microscopy coupled with Energy Dispersive X-Ray Spectrometry and vibrational spectroscopies (Raman, ATR-FTIR). In addition, Gas Chromatography coupled with Mass Spectrometry was employed for the characterization of binding media, using a derivatization methodology recently developed for the detection of metal soaps in paint samples. This extensive characterization aided the identification of the individual constituents and the stratigraphy of green paints. It also builds the foundation for future ageing studies that can provide better insights into the mechanisms of the processes at stake in selective delamination of paints containing copper complexes.

The alum-treated Viking Age archaeological wooden objects from the Oseberg find have undergone extensive chemical deterioration due to the original conservation treatment, based on alum salts (KAl(SO4)2·12H2O), done in the early 1900s. Today, the artifacts are highly acidic (pH≤2) and fragile; in some cases wood has almost completely lost its structural integrity. Research on conservation methods for these finds is currently underway. In the present study, organic/inorganic multi-functional ‘hybrid systems’ – using propylene glycol modified TEOS and alkaline nanoparticles (Ca(OH)2) – have been engineered to deacidify and consolidate alum-treated wood in a single step. The advantage of using silicon monomer and nano-materials as a starting point resides in their ease of penetration into the wood structure, where silicon monomers subsequently undergo polymerization. Treated samples were investigated using thermal analysis (DTG), X-Ray Diffraction (XRD), infrared spectroscopy (ATR-FTIR), SEM/EDX and Gas Chromatography Mass Spectroscopy (GC-MS). Results suggest that in addition to consolidating the wood, alkoxysilanes could act as a bridging agent between remaining lignin and calcium hydroxide nanoparticles.

The late eighteenth century Eidsvoll manor house in Norway was modernised in the first two decades of the nineteenth century. The house and its interiors were colour examined during an architectural paint research. Two colour schemes from the early nineteenth century were found; a light greyish lead white and a green copper-based oil paint. The green colour scheme had discoloured severely. In this paper we discuss the results of synchrotron based infrared spectroscopy experiments on the green paint, which consisted of a verdigris pigment used in oil with lead white and chalk. The analytical results are compared with contemporary recipes found in painters’ handbooks around 1800 and seems to be darker than any recipe provided.

Alum-treated archaeological woods from the Oseberg collection, excavated and treated in the early 1900s demonstrate an extreme deterioration, only discovered in the past decade. This research was aimed at understanding the characteristics of the naturally aged material through chemical analyses of both organic and inorganic components, in order to provide information for the preservation/conservation of these precious objects. Analytical pyrolysis-gas chromatography/mass spectrometry with in situ silylation using hexamethyldisilazane (Py(HMDS)-GC/MS) and inductively coupled plasma-atomic emission spectroscopy (ICP-AES) were used to investigate a set of samples of alum-treated archaeological wood and untreated archaeological wood. Sound woods of the same species were also analysed in order to compare the results. Results from Py(HMDS)-GC/MS analyses of alum-treated woods from Oseberg showed an extreme depletion of carbohydrates and a highly deteriorated lignin network. The majority of the lignin had undergone oxidation reactions, illustrated by high relative amounts of acidic pyrolysis products. In particular, p-hydroxy-benzoic acid was detected for the first time as a degradation product of archaeological wood. Results from ICP-AES showed variable concentrations of aluminium and potassium from the alum treatment, as well as iron, copper, zinc and calcium. The extent of oxidation observed by Py(HMDS)-GC/MS appeared to correlate with relative amounts of iron and calcium in the samples, which may suggest that degradation promoted by iron compounds is inhibited in the presence of calcium compounds. The results obtained for a sample of archaeological wood treated with alum salts five years ago showed that chemical deterioration of lignin had already begun, mainly involving depolymerisation reactions, though only a slight increase in oxidation was evident. In addition to increased insight into potential deterioration reactions, occurring in a complex material such as alum-treated archaeological wood, it was possible to relate the degree of chemical degradation of the Oseberg woods to their visual condition (observed with the naked eye).

Due to problems with most of the existing conservation treatments, new materials for the stabilization of waterlogged archaeological wood are highly desirable. The ideal consolidant should be environmentally friendly and safe to work with for conservators, while strengthening the objects without ruining the visual impression of the wood or filling it in ways that prevent re-treatment in the future. This paper tests chitosan since it is a multifunctional material that not only offers support but also hinders catalytic activity by potentially chelating reactive metal ions. Three solutions of 2% chitosan in 0.1 M acetic acid were chosen as a consolidant for samples from a 1150-year-old piece of waterlogged Viking Age wood from Slagen prestegard. The penetration of chitosan was determined by freeze-drying the samples and analyzing them using high-performance liquid chromatography (HPLC). It was found that chitosan solution penetrated at least 1 cm into the wood along the grain over the span of 2 weeks...

Archaeological wood is usually severely degraded. The Norwegian Viking Age Oseberg find exemplifies problems arising due to past conservation treatments and the need for new types of preservatives. Phenol formaldehyde (PF) has been investigated as a consolidant for alum-treated wood. X-ray tomography has revealed that it is possible to obtain a porous structure inside the wood, ensuring ethical acceptability by allowing re-treatment. In order to understand the curing mechanics, the kinetics of the initial condensation reaction were elucidated at room temperature. It was found that a second-order reaction using both phenol and formaldehyde concentrations is the most probable mechanism.

Waterlogged archaeological wood is often in need of consolidation prior to drying to prevent shrinkage and cracking of the object. There is a need for new greener materials (than for example polyethylene glycol) and methods for consolidation to be developed. The use of wood-based components could provide good interaction between the consolidant and the remaining wood structure and would also support a shift away from fossil fuel-based materials to those with more sustainable sources. Based on this, lignin-like structures have been investigated for their ability to consolidate waterlogged archaeological wood. The in situ formation of a lignin-like material has been carried out using isoeugenol polymerised by horse radish peroxidase in aqueous solution. The formation of the oligomeric/polymeric materials within the wood following this reaction has been determined by Attenuated Total Reflectance Fourier Transform Infra Red (ATR-FTIR) spectroscopy. The oligomers remaining in solution have been characterised by ATR-FTIR and nuclear magnetic resonance (NMR) spectroscopy as well as analytical ultracentrifugation, showing that they have a weight average Mw of 0.4–0.9 kDa and a lignin-like structure rich in the β-5′ moiety. Therefore, this approach is proposed as a basis to further develop a green consolidation method for waterlogged archaeological wood.

Metastable 4-methyl benzophenone (4-MBP, C14H12O) crystallizes in the polar (pyroelectric) and enantiomorphic space groups (SG) P31 and P32. The optical rotation tensor has been measured for 670 nm and the material was tested for evidence of phase-matchability. The absolute structure was determined via three-beam diffraction, showing that the structural right-hand screw 31 is combined with positive (right-handed, i.e. clockwise when looking towards the light source) optical rotation, for both tensor components ρ 11 = ρ 22 = 26(5)°/mm, ρ 33 = 8.3(5)°/mm (contrary to low-quartz which shows negative optical rotation for ρ 33 and positive rotation for ρ 11 in right-hand SG P312). The non-linear optical tensors for optical rotation, d-coefficients, electro-optic effect and electrogyration have been calculated using a set of electronic polarizabilities as input parameters for a dipole-dipole interaction model that reproduces the experimental refractive indices and optical rotation. Unusually high polarizability volumes are needed for hydrogen atom bonding to aromatic carbons in order to model the optical tensors. The non-linear optical coefficients are of medium size.

Given the perilous state of the Oseberg find from Norway, the Museum of Cultural History and the Department of Chemistry both at the University of Oslo, are looking into new methods for treating archaeological wood. While numerous polymers have been previously tested, most do not stabilise the wood sufficiently, penetrate far enough, or remain stable without producing toxic fumes. A few of the more common examples are: Alum salt, KAl(SO 4 ) 2 ·12H 2 O, which was used for treatment earlier but does not penetrate well and leaves the wood very acidic. Poly(oxy ethylene) (POE or Polyethylene glycol [PEG]) is widely used as a consolidant today but this material degrades over time and thus cannot support the finds for a very long time. Melamine-formaldehyde (Kauramin) has also been used and while it is fairly stable, it may also fill the wood and turn it into a ‘block’ of plastic. Since new consolidants would be advantageous, it is discussed what the requirements of such consolidants are and how material sciences may help procure them. It is proposed that an important requirement for a future stabilising agent is to leave an airy structure in order to allow retreatment in the future. This might be accomplished by foaming a polymer, or by combining nanoparticles with a polymer ‘spider web’ network to keep them in place. Such particles may help stabilise pH inside the wood by neutralising any acid generated inside treated artefacts. Special attention is given to the field of biomimetics–the discipline of constructing materials inspired by existing natural designs. It may be possible to construct a frame using bio-inspired materials (possibly an ‘artificial lignin’ mixed with other compounds optimise strength and flexibility) or through biomineralisation (an inorganic ‘skeleton’). Tests on biomimetic cellulose and chitosan have begun and the initial evaluation of these materials is given. Chitosan is made from modified chitin (primarily from shrimp and crabs) and may be dissolved in acidic solutions. Crystalline cellulose is interesting in conservation as the individual particles are resistant to acid and not as hygroscopic as the amorphous part of cellulose. The materials and the procedures used in testing are described. It is shown that crystalline cellulose particles usually flocculate when used to treat archaeological wood but that they may be treated with surfactants in order to improve penetration of archaeological finds.

The development of new materials for the consolidation of waterlogged archaeological wood from sustainable sources is an important area of research, as the most widely used consolidant today is petroleum based. Ideally a new consolidant will interact with the existing wood structure, ensuring maximum compatibility. Lignin is often the major component remaining in archaeological wood, as it is less susceptible to degradation than holocellulose. Therefore, in order to maximise the potential for interaction with the wood cells, lignin-like oligomers have been synthesized from isoeugenol using a water soluble copper salen catalyst at pH 10, giving a weight average Mw of 1.6 kDa. Analysis by NMR spectroscopy has shown that the oligomers have a lignin-like structure with β-O-4′, β-β′ and β-5′ connections. A 10 w/w% solution of the oligomers in ethyl acetate was found to thoroughly penetrate 1 cm3 samples of waterlogged archaeological wood (density of 0.146 g/mL, maximum water content of 620%) after 14 days impregnation, as determined by FTIR spectroscopy. No impregnation material could be seen by SEM, suggesting that it coats the cell walls upon drying. This indicates that dehydrogenated polymers penetrate waterlogged archaeological wood well and have the potential to be developed into consolidants.

2,3-Diphenyl maleic acid anhydride (DPMA), (C6H5)2C4O3, is a “historical” compound for which polymorphism, crystal morphology and fluorescence were first reported by Drugman in 1912. For 2,3-diphenyl maleic imide (DPMI), (C6H5)2C4O2NH, crystallographic data have not been reported previously. In this work the polymorphs of DPMA have been crystallised from various solvents, from the supercooled melt and from the vapour phase. Small single crystals of the stable, orthorhombic α-phase (m.p. = 156 °C, ρ = 1.334 g/cm3) and of the metastable, monoclinic β-phase (m.p. = 146 °C, ρ = 1.350 g/cm3) were obtained, as described by Drugman. In addition, a fine powder of a previously unknown second metastable phase γ(m.p. = 149 °C) was crystallised. For DPMI, a stable, triclinic α-phase (m.p. = 216 °C, ρ = 1.307 g/cm3) and a metastable, monoclinic β-phase (m.p. = 212 °C, ρ = 1.296 g/cm3) were observed. The structures of the α- and β-polymorphs of DPMA and DPMI were determined by single-crystal X-ray diffraction. Space groups are Pbca for α-DPMA, P21/c for β-DPMA, P-1 for α-DPMI and C2/c for β-DPMI. In both DPMA polymorphs van der Waals interactions dominate. In both phases of DPMI, pairs of molecules form centrosymmetric dimers via H—N…O hydrogen bonds. Between the dimers significant van der Waals interactions exist. Lattice energy calculations based upon the Dreiding force-field using individual molecules as the building blocks for the crystal lattice yield reasonable energy values for DPMI. For DPMA, however, the calculated lattice energy is significantly higher for the stable phase than for the metastable phase. This observation correlates with the observed violation of the density rule for polymorphs, with ρ α < ρ β, and is discussed here in terms of the different conformational energies of the molecules. The results of fluorescence and Raman spectroscopic measurements on the α- and β-polymorphs of both DPMA and DPMI are reported.

Modern and contemporary art collections show an increasing number of paintings with softening oil paints, exudates, and even drips. Since 2013 the condition of the paints on ca. 100 paintings from ...

Modern oil paints, introduced at the beginning of the 20th century, differ from those classically used in antiquity in their chemical and compositional features. The main ingredients were still traditional drying oils, often used in mixtures with less expensive oils and added with several classes of additives. Consequently, detailed lipid profiling, together with the study of lipid degradation processes, is essential for the knowledge and the conservation of paint materials used in modern and contemporary art. A multi-analytical approach based on mass spectrometry was used for the study of original paint materials from Munch's atelier, owned by the Munch Museum in Oslo. The results obtained in the analysis of paint tubes were compared with those obtained by characterizing a paint sample collected from one of the artist's sketches for the decoration of the Festival Hall of the University of Oslo (1909-1916). Py-GC/MS was used as screening method to evaluate the presence of lipid, proteic or polysaccaridic materials. GC/MS after hydrolysis and derivatization allowed us to determine the fatty acid profile of the paint tubes, and to evaluate the molecular changes associated to curing and ageing. The determination of the fatty acid profile is not conclusive for the characterization of complex mixtures of lipid materials, thus the characterization of the triglyceride profiles was performed using an analytical procedure based on HPLC-ESI-Q-ToF. This paper describes the first application of HPLC-ESI-Q-ToF for the acquisition of the triglyceride profile in a modern paint sample, showing the potentialities of liquid chromatography in the field of lipid characterization in modern paint materials. Moreover, our results highlighted that the application of this approach can contribute to address dating, authenticity and conservation issues relative to modern and contemporary artworks.

In this paper we report the crystal structure solution of a meta-stable phase of phenyl salicylate (salol). This modification, which is obtained from a super-cooled melt, has been observed before, but the structure has not been previously determined. Structure solution was achieved by a procedure combining a computer based systematic search method with a subsequent Rietveld refinement of experimental X-ray powder diffraction data. A clustering procedure to group similar trial structures based upon energy minimisations is discussed. The best trial structure identified by the combination of a systematic search and clustering was refined using the Rietveld method and a final structure with a weighted pattern indexRwpof 0.0513 (excluding background) was obtained. The meta-stable phase of salol crystallises with a monoclinic unit cell with cell parametersa= 17.4047(8) Å,b= 5.9800(5) Å,c= 10.6882(7) Å, and β = 108.988(5)º. The space group isP21/nwith four molecules in the unit cell. A structural comparison of the stable and meta-stable modifications is given.

Iory is richer in magnesium than other bone or dental material. In the older mineralogical literature there are a few reports of the occurrence of the magnesium phosphates bobierrite [Mg3(P04)2·8H2O], newberyite (MgHP04·3H2O) and Siruite (MgNH4P04·6H2O) in excavated mammoth or elephant tusks. Newesely found newberyite deposits on ivory artifacts, which is confirmed in this study. As bleaching wilh ammoniacal hydrogen peroxide damages ivory and leads to Struvite crystals, it should be abandoned. The roles of chemical and microbiological factors in the formation of magnesium phosphates from ivory are discussed.

An overview of recent work directed to the crystallographic structure solution of organic solids using a combination of X-ray powder diffraction and a grid-based direct space search for trial structures is presented. A number of study cases illustrate the application and potential of this approach. Additionally, the inherent limitations of powder diffraction as an isolated tool for structure determination are discussed together with an outline of ways to address these limitations in the future.

Plant surfaces are mostly covered with microscopic layers of wax which exhibit characteristic morphologies, visible under high magnification. Waxes belonging to three different types were investigated. Powder data of seven natural and three recrystallised waxes as well as of two isolated compounds are presented. The mainly crystalline nature of the studied plant waxes is proved. The correlation between morphology, chemical composition, and powder patterns is discussed.

Pyroelectric, dielectric and piezoelectric coefficients of metastable 4-methylbenzophenone, point group 3, have been determined by standard methods. Furthermore, thermal expansion and elastic properties of this phase and of the stable monoclinic phase have been studied. The pyroelectric effect is comparable with that of tourmaline, the piezoelectric effects to those of a-quartz. The differences between the two polymorphs with respect to thermal expansion and to elastic and thermoelastic properties are small, but nevertheless significant.

Benzophenone was the first organic molecular material to be identified as polymorphic. It is well known that benzophenone crystallizes in a stable orthorhombic α-form (m.p. 321 K) with space group P212121 and a = 10.28, b = 12.12, c = 7.99 Å, [Girdwood (1998). Ph.D. thesis. Strathclyde University, Glasgow, Scotland]. Here we report two separate structure determinations of the metastable β-form (m.p. 297–299 K). Crystalline material of the metastable polymorph was obtained from a melt supercooled to ∼243 K. The structure was determined from X-ray powder diffraction data by employing a novel, computational systematic search procedure to identify trial packing arrangements for subsequent refinement. Unit-cell and space-group information, determined from indexing the powder diffraction data, was used to define the search space. The structure was also determined from single-crystal diffraction data at room temperature and at 223 K. The metastable phase is monoclinic with space group C2/c and a = 16.22, b = 8.15, c = 16.33 Å, β = 112.91° (at 223 K). The structures derived from the individual techniques are qualitatively the same. They are compared both with each other and with the stable polymorph and other benzophenone derivatives.

The project Saving Oseberg is funded by the Norwegian State with the aim to preserve the Viking Age wooden objects from the Oseberg burial mound. They were excavated in 1904 near Tonsberg, Norway, and many have been treated in the past with alum salts (KAl(SO4)2·12H2O). Alum was widely used during the early 1900s as a treatment for archaeological wood to prevent shrinkage and impart strength. In the 1990s, conservators observed an alarming condition of the objects. Initial investigations showed that the alum treatment has initiated a slow but ongoing deterioration process, attacking the wood for over 100 years. Today, the artefacts are highly acidic and have significantly reduced mechanical strength. In the last decade, the use of non-aqueous alkaline nanoparticle dispersions has provided successful results for the protection of cellulose-based materials. Alum-treated archaeological wood samples from Oseberg, with a pH ≤ 2, have been treated with alkaline nanoparticle dispersions, and the effects of the treatment have been evaluated by thermal analysis (TG-DTG), infrared spectroscopy (ATR-FTIR) and X-ray microtomography (micro-CT) analyses. In this contribution, the preliminary results will be presented.