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Among the innovative materials used by 20th-century artists, polyurethane (PUR) has been shown to be highly unstable, and therefore artworks made of it are now in need of careful conservation strategies. This study presents a multi-analytical investigation of PUR foam scenic objects originally made between the 1960s and 1970s during the Italian Arte Viva movement. The main components in the foam and additives were characterized through micro attenuated total reflectance infrared spectroscopy (μ-ATR-FTIR) and pyrolysis coupled with gas chromatography and mass spectrometry (Py-GC/MS). Painted samples were further investigated through μ-FTIR and Raman spectroscopy to define binders and pigments. The use of μ-ATR-FTIR in combination with evolved gas analysis-mass spectrometry (EGA-MS) allowed the variable conditions of the artworks to be assessed and attained some insights into the chemical processes responsible for aging. At the same time, morphological changes due to the degradation phenomena were recorded through optical (OM) and scanning electron microscopy (SEM). The detailed characterization of the PUR foam and painting materials was helpful in attaining some insights into harmful environmental parameters for the artworks, thus informing preventive conservation.

In this review, the main technological processes involved in the production of color in glasses, ceramics and pigments are reported. Iron (as oxides or dispersed ion) is the main responsible of the color in archeological and historical ceramics and glasses, but other d-metals can be also found (Cu, Ag, Co, Cr, Ni) as nano-particles or dispersed ions. The final coloration is usually a result of the sapient choice of raw materials and firing conditions (temperature, atmosphere). Some pigments are chosen to represent the different, often sophisticated, chemical processes that have been used during the history to produce them: solid state reaction (Egyptian and Chinese Blue, Naples Yellow, Ultramarine Blue), host-guest complexation (Maya Blue), corrosion/redox processes (Lead White, Verdigris), wet/solution synthesis (Prussian Blue, Cadmium Yellow). In addition, a brief overview on the vast production of modern compounds (inorganic and mostly organic) is given. This review shows how behind the artistic choice and way of expression lies a high level of technological skill and chemical knowledge achieved/reached by (ancient) craftsmen to obtain the desired colors.

The Attirement of the Bride, painted by Max Ernst in 1940, is permanently on display in the Peggy Guggenheim Collection (PGC) in Venice. Within the framework of a larger study of materials and techniques of works by Ernst at the PGC, researchers carried out a series of non-invasive analyses. A combined approach based on Vis-NIR multispectral imaging, Raman Spectroscopy, X-Ray Fluorescence (XRF), and External Reflection Fourier Transform Infrared Spectroscopy (ER-FTIR), was conducted insitu in the museum galleries. In addition, two micro-samples were analysed with SEM-EDS and μ-Raman. This approach produced vital information on the preparatory drawing, the pentimenti, the pigments, the extenders and the alteration products present in the painting. The results showed also the presence of a white preparatory layer, under the pictorial one and above the canvas, composed by lithopone (a mixture of zinc sulphide and barium sulphate), basic lead carbonate and calcium carbonate. The latter compound is probably present also as an extender. The palette included both traditional and new synthetic, commercial pigments, used as primary colours or in mixtures. Moreover, in several areas of the painting, zinc oxalates have been identified as alteration products and more rarely, zinc metal soaps, which could also be present as additives in the paint tube. These analyses revealed the masterful and innovative painting technique of this pioneer of Surrealism.

The durability of Portland cement mortars is often affected by environmental factors, which can cause physicochemical and mechanical degradation processes. In this study, the performance of three products, calcium acetoacetate and calcium tetrahydrofurfuryloxide dissolved in two different solvents developed and tested as stone consolidants, was evaluated in terms of crack filling or sealing and consolidation. Realistic cracks were induced in quasibrittle cement mortar prisms using a custom-designed test rig. The effectiveness and the performance of the considered treatments, investigated on specimens, were evaluated by optical and scanning electron microscopy, colourimetry, water absorption rate, ultrasonic pulse velocity, and surface hardness measurements. Results revealed that, in the examined conditions, the products were more suitable as surface consolidants than as crack fillers. Nasl. z nasl. zaslona. Opis vira z dne 4. 5. 2022. Št. članka 4044. Bibliografija: str. 12-14. Abstract.

Giulio Turcato (Mantova 1912–Rome 1995) was an Italian artist, belonging to the figurative and abstract expressionist currents. At the end of the 1960s, fascinated by the US space program, Turcato produced a series of artworks, differing in colour and shape, titled Superficie Lunare (Moon Surface). To reproduce a realistic moon surface, Turcato used polyurethane foam as support for the painting. The combination of this unconventional material and the pictorial ones makes Superficie Lunare an interesting case of study to understand the alteration phenomena in contemporary art. In this study, a blue painted Superficie Lunare (1969) was analysed by means of non-invasive (ER-FTIR, Raman and X-ray spectroscopy) and micro-invasive techniques (µ-ATR, μ-FTIR, μ-Raman, Py-GC/MS, EGA-MS and SEM-EDS). The results point out the use of a polyurethane foam as support and of a poly(vinyl acetate) based Prussian blue paint tube as main constituent of the paint layer. The analyses highlight also the complexity of the paint layer, showing the presence of lampblack and Al foil mixed to the blue paint, lithopone inside the white crater and possibly ferric oxide in the red one. The results confirm the use of a polyurethane foam for the support. The painted layers present a binder composed of poly(vinylacetate), with polystyrene, possibly present as additive. Concerning the nature of the blue pigment, Prussian blue was identified on the whole surface. In some points, also lampblack was detected. Furthermore, small foils of Al were found inside the paint layer, probably to give sparkling effect. Inside the moon craters, lithopone was identified for the white pigment and possibly iron oxide for the red one. The multi-technique approach allowed also to obtain information about the manufacturing of the used Prussian blue and the occurrence of alteration process for the polyurethane foam.

Metal alkoxides are metal-organic compounds characterized by the presence of MOC bonds (M = metal). Their chemistry seems to be, in principle, relatively simple but the number of possible reactant species arising as a consequence of their behavior is very remarkable. The physico-chemical properties of metal alkoxides are determined by many different parameters, the most important ones being the electronegativity of the metal, the ramification of the ligand, and the acidity of the corresponding alcohol. Their reactivity makes them suitable and versatile candidates for many applications, including homogeneous catalysis, synthesis of new ceramic materials through the sol-gel process and, recently, also for Cultural Heritage. Metal alkoxides are characterized by a strong tendency to give clusters and/or oligomers through oxo-bridges. Mass spectrometry has been successfully employed for the characterization of metal alkoxides in the gas-phase. Electron ionization (EI) allowed the assessment of the molecular weight and of the most relevant decomposition pathways giving information on the relative bond strength of differently substituted molecules. On the other hand, information on the reactivity in solution of these molecules have been obtained by electrospray ionization (ESI)-matrix assisted laser desorption ionization (MALDI) experiments performed on their reaction products. These data were relevant to investigate the sol-gel process. In this review, these aspects are described and the results obtained are critically evaluated. © 2016 Wiley Periodicals, Inc. Mass Spec Rev.

The paint media used by contemporary artists include a wide range of formulation of industrially produced paints based on synthetic resins and natural oils. We investigated the paint media used by the British artist Alexis Harding (born in 1973) in the painting “Quartet” (2003). The artwork exemplifies the artist's technique of mixing different paint media to obtain a sliding movement of the paint over the support, raising severe conservation issues and causing long-term instability of the paint. As a basis to develop a conservation strategy for the artwork, we investigated the composition of the paint by in situ non-invasive contactless external reflection infrared spectroscopy (ER-FTIR). The combination with laboratory analytical techniques applied on micro-samples allowed the identification of the pigments and the binders. The multi-analytical approach involved micro infrared spectroscopy (µFTIR), Raman spectroscopy, X-ray fluorescence (XRF), and mass spectrometric techniques coupled to chromatography (GC/MS and HPLC-ESI-Q-ToF) and analytical pyrolysis (Py-GC/MS and EGA-MS). The results of these micro-destructive investigations showed that the causes of the gliding of the paint are due the incompatibility between different materials superimposed by the artist: a fast drying alkyd paint and a mixture of siccative and non-siccative drying oils.

During the European NANOMATCH project (funded under FP7 GA no. 283182) two alkoxides, calcium tetrahydrofurfuryloxide and calcium ethoxide, were developed and tested as new products for stone and stone-like consolidation [1, 2]. Their behavior in atmosphere makes them suitable products for conservation of calcareous stone: in fact they react with humidity and carbon dioxide to give CaCO3. In this paper we report the results of an investigation aimed to understand the influence of different parameters (RH, solvents, concentration) on the carbonation process and on the formation of the final coating, in particular as far as the crystalline form is concerned (vaterite, calcite, portlandite). Solution of alkoxides in different solvents (different alcohols, n-butylacetate, ligroin) were prepared at two concentrations (5g/L and 20g/L in Ca). Kinetic of carbonation was investigated through ?-FT-IR. The solutions were then applied on glass slides and maintained two weeks either at environmental conditions or at controlled RH conditions (50% and 90%). The resulting coatings were then characterized by ?-FT-IR, XRD and SEM. Results indicate that the most important factors influencing the kinetic and the final products are the humidity and the features of the employed solvents. [1] I. Natali, P. Tomasin, F. Becherini, A. Bernardi, C. Ciantelli, M. Favaro, O. Favoni, V. J. F. Pérez, I. D. Olteanu, M. D. R. Sanchez, A. Vivarelli, A. Bonazza, Innovative consolidating products for stone materials: field exposure tests as a valid approach for assessing durability. Heritage Sci., 3 (6), 2015. [2] M. Favaro, M. Chiurato, P. Tomasin, F. Ossola, N. El Habra, N. Brianese, I. Svensson, E. Beckers, V. Forrat Pérez, M. Romero Sánchez, G. Orial, E. Bourguignon, A. Bernardi, Alkaline earth alkoxides for conservation treatment of stone and wood in built heritage. In Proceedings of 3rd European Workshop on Cultural Heritage Preservation (EWCHP) Bolzano, Italy. 2013.

Pore-space properties, such as pore-size distribution and connected porosity, are relevant factors in the evaluation of the performance of a consolidation treatment. In this study, two different techniques – Mercury Intrusion Porosimetry (MIP) and Nuclear Magnetic Resonance Relaxometry (NMRR) – were adopted to study the compatibility and the efficacy of a new consolidation product for limestones. This work aims at comparing and combining data obtained by MIP and NMRR; to confirm the relationship between the quantitative results of MIP and the qualitative ones of NMRR, a calibration which leads to correlate T2 distribution and pore size distribution has been applied. Experimental results showed that, in most cases, NMRR results agree with MIP data. Therefore, NMRR technique can be considered a powerful tool to evaluate the change in pore size distribution due to the application of a consolidating agent on stone, especially in cases when sampling should be avoided.

Calcium ethoxide nanosuspension, a consolidating product developed during the European Nanomatch project, is here modified by adding two different solvents, 2-butanol and n-butylacetate, chosen for their different boiling points with respect to ethanol, the solvent employed in a previous work to dilute the original product. Fourier transform infrared spectroscopy (&micro, FT-IR) was used to understand how the presence of these new solvents can influence the kinetics of the carbonation process and the pathway reaction. Furthermore, coatings derived from nanosuspensions were maintained for specific time intervals at controlled relative humidity conditions (RH = 50% and RH = 90%), the formed mineralogical phases were characterized by &micro, FT-IR and X-ray diffraction (XRD). Results indicate that the used solvents can influence the kinetic and reaction pathways, while the phases formed at the end of the carbonation process are influenced by both solvents and RH conditions. The effectiveness of calcium ethoxide based product diluted in 2-butanol and n-butylacetate as limestone consolidants was evaluated with drilling resistance measurement system (DRMS) and ultrasound pulse velocity (UPV). The impact on color coordinates was also assessed. The results were compared with those obtained with the same product diluted in ethanol and a commercial nanolime. The use of these solvents gave different and better results in terms of efficacy.

The present study reports the results of a combined approach in investigating the alteration phenomena on a contemporary artwork, Senza Titolo, by Nunzio di Stefano. The oeuvre, created in 2001, is composed by seven lead carved panels coated with Paraloid B72. After having being stored for several years in wood boxes, it was acquired in 2015 and, only at that time, the surface showed an evident deterioration In situ analyses, by means of contactless external reflection infrared spectroscopy (ERFTIR), have shown that the alterations products are in the form of basic lead carbonate and, surprisingly, of lead carboxylate. The presence of these products were supposedly due to VOCs attack during the storage in wood boxes. The formation of lead carboxylate, due to the interaction among lead substrate and acetic and formic acids (the major components of the VOCs mixture), was investigated through a laboratory accelerated ageing. The effect of VOCs was studied on the lead substrate, on the acryl coating and on a series of mockups simulating Senza Titolo. The combination of surface and punctual analyses, by means of ERFIR and mu-FTIR, showed that the formation of alteration products is a relatively fast process. The alteration path involves firstly the absorption of VOCs moisture on the Paraloid B72 surface, immediately followed by corrosion processes, leading to hydrocerussite, lead acetate and formate. The presence of the polymeric coating controls the transformation of lead carboxylates to basic lead carbonate. Laboratory results have consolidated those obtained by in situ contactless investigations, confirming ERFTIR as powerful tool in assessing the state of conservation of Cultural Heritage materials. (C) 2018 Elsevier Masson SAS. All rights reserved.

The combination of multiple physical, chemical and biological factors causes the weathering of limestone used in the field of cultural heritage. To overcome the limitations of traditional consolidating products and to meet the requirements of the historical building substrates, during the European collaborative project NANOMATCH, alkaline earth alkoxides were developed and studied as consolidating agents for limestone. Among these new products, calcium ethoxide, with the formula Ca(OEt)2, was chosen for this study and investigated in depth as an alternative consolidating treatment. It was first characterized through a study of the carbonation process: its kinetics, reaction pathway and the evaluation of formed mineralogical phases. Subsequently, it was applied on limestones with different total open porosity to test its performance as a consolidating agent. The compatibility and the efficiency of the treatment were investigated with a multi-technique approach and compared with results obtained with a reference product, based on nanolime. This study indicates that calcium ethoxide shows better results with respect to the reference product, both in terms of compatibility and consolidation effect.

In the field of cultural heritage conservation, wall paintings treatment is a particularly complex issue, which requires a suitable choice of materials. In this paper, two innovative calcium alkoxides, calcium tetrahydrofurfuryl oxide [Ca(OTHF) 2 ] and calcium ethoxide [Ca(OEt) 2 ], are proposed as new products for the consolidation of wall paintings. They were developed during the NANOMATCH European project and their efficacy, compatibility with the substrate and durability were evaluated in comparison with commercial products on both model and real samples. Model samples were exposed in four different sites around Europe to investigate the treatments’ behaviour under different climatic conditions. The main research results are reported here: alkoxides showed to be a good option for wall paintings’ consolidation especially in presence of certain binders and pigments. Finally, an impact testing device was used for the first time for the evaluation of the consolidants’ efficacy and thus proposed as a reliable methodology for their performance assessment.

presentazione in tipologia "elevator pitch" del progetto europeo/innovazione NANOMATCH

Electrospray ionization was applied on calcium alkoxides studying the most suitable operative conditions for their detection/identification. To reach this aim, calcium methoxide and ethylate were obtained by two different synthetic pathways, in order to understand their possible different aggregation states. The reaction mixture shows the presence of a supernatant and of a precipitate poorly soluble in most organic solvents. The purpose of this preliminary study is to understand the qualitative differences between the precipitated species and the ones in solution by analyzing both of them with the same analytical method. The electrospray ionization (ESI) operating conditions (voltages, temperatures, solvents) allow not only the detection of single species but also the study of clusters present in solution. Particular attention was paid to establishing the role of ESI conditions in the formation of the detected species. Experiments performed at different sprayer voltages (1 kV, 2 kV, 3 kV and 4 kV) proved that ESI does not perturbate the equilibria present in the original solution, demonstrating that the technique can be a useful tool to achieve information on this class of compounds.

Purpose In this study, the environmental performance of three newly developed materials for the conservation of built Cultural Heritage is preliminary evaluated by means of life cycle assessment (LCA). Although LCA has been adopted since many years in many fields, including the construction industry, still it is barely used the field of the Cultural Heritage conservation. Therefore, this paper aims to put a step forward to a wider use of the method for a more sustainable conservation of built heritage. Methods Cradle-to-gate approach was applied, which includes activities beginning with production of constituent and ancillary materials and concluding with the manufacturing of the product and its packaging. The functional unit was the production of 1 kg of the consolidant stored in a canister and ready to use. Ecoinvent database was used for the life cycle inventory of chemicals. This database was also taken into account to evaluate impacts related with energy (electricity) needs during manufacturing of the consolidants and production of polyethylene canisters (packaging material). The IMPACT 2002+ method was used to select the impact categories. Results and discussion The consolidants under investigation are calcium acetoacetate and two calcium alkoxides (calcium ethoxide and calcium isopropoxide). In the case of calcium acetoacetate consolidant, the highest environmental impact is related to the use of acetone dicarboxylic acid as raw material. Manufacturing process of the final product is not an energy-demanding process; hence, it is regarded as relatively clean from the environmental point of view. In the case of calcium ethoxide and calcium isopropoxide nanosuspensions, the innovative materials just recently developed for conservation purpose, manufacturing has been performed and optimized at a kg/lab scale; therefore, the results must be considered provisional. The two calcium alkoxides nanosuspensions show a relatively high environmental footprint that reflect the high consumption of ancillary materials, i.e. solid CO2 used to cool down the reaction and liquid ammonia as catalyst, currently released in the atmosphere. Conclusions The environmental footprint of calcium acetoacetate is relatively low showing that 1 kg of the consolidant is associated to 0.32 kg of CO2 equivalent emissions. In the case of two calcium alkoxides nanosuspensions, the global warming impact amounts to 198 kg (calcium ethoxide, 1 kg) and 132 kg (calcium isopropoxide, 1 kg) of CO2 equivalent emissions. Given the planned optimization of the industrial production currently under investigation, the environmental footprint of the two calcium alkoxides nanosuspensions is expected to reduce between 60 and 85%.

The present study dealt with the characterisation of marble surfaces coated by three kinds of polymeric material usually employed in stones conservation and with the evaluation of the removal of these coatings from the surfaces by means of new nanocontainer aqueous systems constituted of micellar solutions (MS) and oil-in-water microemulsions (MC). The polymeric coatings were also subjected to accelerated artificial ageing in order to detect possible effects associated to natural photochemical ageing. The aim of the work was the assessment of the performance of such nanocontainer aqueous systems taking acetone (Ac) as a reference “traditional” solvent for the removal procedure. The characterisation was carried out by means of Scanning Electron Microscopy (SEM) and Environmental Scanning Electron Microscopy (ESEM), Fourier Transform Infra-Red (FTIR) and Nuclear Magnetic Resonance (NMR) spectroscopies and the results obtained showed that the performance of these innovative methods based on nanocontainer aqueous systems can be considered highly promising in the view of a “green approach” to the conservation of cultural heritage.

The behaviour of the acrylic–silicone mixture commonly known as Bologna Cocktail, composed of commercial acrylic polymer Paraloid B72 and the silicon-based product, Dri Film 104, extensively employed as stone preservative for monuments in the last thirty years, has been tested on specimens appropriately prepared and submitted to ageing simulating reliable outdoor environment. After chemical characterization, the acrylic–silicone mixture was applied as thin film on slides, as thick film on Petri dishes and on marble by brush or by absorption; the resulting samples were artificially aged by light and saline solution. The chemical modifications were evaluated by FT-IR, NMR and SEC determinations, while preservative properties were tested by removability tests, ultrasonic and colorimetric measurements. The mixture consists of two immiscible phases and the two components have distinctive chemical behaviours, leading – after ageing – to irreversible molecular modifications and loss of conservative properties. The deterioration processes identified through laboratory simulation have been also verified on treated marble surfaces of two Venetian case studies.

The impact of climate on cultural heritage surfaces leads to several damage processes and the protection and the preservation of works of art is a challenge for conservation scientists and restorers. Traditional and innovative products are used in consolidating treatments in order to reduce the effects of the interaction environment-materials. The EC NANOMATCH Project aims at the development of innovative consolidating agents for carbonate matrices, wood and glass whose features should result in high compatibility, efficiency and long-lasting effect. In this project, metal alkoxides, molecular precursors for the deposition of metal carbonate are synthesized, characterized, tested and proposed as an alternative to traditional consolidating agents as well as to calcium hydroxide nanoparticles. This paper gives an overall description of the methodological approach adopted for the in field evaluation of durability taking into account the environmental impact. Preliminary results of the analyses carried out on carbonate stones aimed at investigating the features of the consolidating treatment are here presented and discussed.

In the frame of the EU-project NANOMATCH new consolidants based on metal alkoxides were developed and tested. New compounds were prepared with different synthetic pathways to overcome the oligomerization issue, which can strongly influence solubility and therefore application of alkoxides as conservation materials for built heritage. Calcium alkoxides react in presence of humidity and carbon dioxide to give CaCO3 and alcohols. This peculiar behavior -in atmospheric conditions- makes this class of chemicals suitable for consolidation of carbonate stones, plasters and wall paintings and also for pH buffer to avoid acidification of cellulose based materials such as wood and paper. Within the frame of the project, it has been demonstrated that the developed calcium compounds are more soluble than the corresponding commercial Ca-bearing consolidants and, after reaction with air, they evolve into different calcium carbonate structures, i.e. amorphous carbonate or crystalline calcite and vaterite. The ratio among these forms can be oriented by environmental conditions and treatment with water, in order to force a carbonate phase in place of other ones. Commercially available magnesium alkoxides solutions were also tested as consolidants precursors. Carbonation of magnesium compounds brought to precipitation of low crystalline Mg hydroxide and carbonate coatings. Moreover, hydrated Mg carbonate phases were identified. Many of them are salts sensitive to water and prone to ion-exchange, possibly evolving to soluble magnesium salts deleterious for stone. These experimental evidences led to the decision to discard magnesium alkoxides for conservation purposes.

Potential utilization of calcium alkoxides as stone consolidants was considered. Reaction of Ca(OCH3)2, Ca(OCH2CH3)2(CH3CH2OH)4 and Ca[OCH(CH3)2]2 with the atmosphere in different experimental conditions was studied. The reaction produced CaCO3 and two different pathways seem to be involved, the first taking place through CO2 insertion into the Ca–O bond of Ca(OR)2 species with formation of an alkylcarbonate derivative, subsequently transformed into CaCO3 through ROH elimination; the second takes place through hydrolysis of Ca(OR)2 to Ca(OH)2, which is then carbonated to CaCO3. The vaterite/calcite ratios found in the final CaCO3 vary considerably with the experimental conditions adopted. Investigations demonstrated the potentiality of Ca(OCH3)2 to act as a stone consolidant. In fact, impregnation of a porous substrate, simulating the deteriorated stone, with a methanol solution of Ca(OCH3)2, produced a crystalline vaterite film, which gradually filled all the pores and cavities of substrate and seems to fulfil the necessary requirements for a consolidant. Copyright © 2008 John Wiley & Sons, Ltd.

The commercial acrylic polymers, Paraloid B72 and Paraloid B67, and a silicon-based product, Dri-Film 104, commonly used as water repellents/consolidants in the restoration of stone artefacts, have been tested to evaluate their performances when submitted to ageing, simulating the outdoor conditions of treated stone. After full characterization, the three polymers were applied as thin films on slides, as thick film on petri dishes and on marble by brush or by imbibition and the resulting samples were submitted to photo-oxidative weathering (λ = 340 nm). The weathering evolution was checked by ultrasonic and colorimetric measurements and by FT-IR, NMR and SEC determinations. Removability tests were also performed. All the polymers underwent irreversible modifications with reduction of their conservative properties, colour change and, above all, impossibility of their complete removal.

Electrospray ionization mass spectrometry (ESI-MS) was successfully employed for the identification of six nitrido technetium mixed ligand complexes with a general formula of [99gTc(N)(O,S-BID)(PNP)], where PNP represents a heterodiphosphine and O,S-BID represents a simple dianionic bidentate ligand (compounds 1–3) or a more sophisticated N-substituted O,S-cysteine framework conjugated with a bio-active molecule (BAM) (compounds 4–6). In spite of similar coordination spheres exhibited by all the complexes investigated, simple co-ordination compounds 1–3 displayed collisionally-induced fragmentation processes (MSn) different from those observed in biomolecule-containing compounds 4–6. In the latter, more decomposition channels were observed. This behavior is likely to be associated with some additional intramolecular contacts of the biomolecule (or part of the biomolecule) with pendant group(s) incorporated in the PNP-co-ligand. This view is further supported by the observations arising from both in vitro binding affinity experiments and nuclear magnetic resonance investigations. The presence of cationized forms for all compounds 1–6 and the practical lack of the [2M + Na]+ species for biomolecule-containing compounds 4–6 provided further evidence of a subtly different structural conformation.

Calcium alkoxides in solution give rise to oligomers with different reactivity and solubility and, as observed in a previous investigation, small differences in the ligand structure lead to strong differences in the cluster composition. Electrospray ionisation mass spectrometry (ESI-MS) gives evidence of this behaviour, allowing the identification of these oligomers. In this paper, ESI was applied in the study of calcium alkoxides with different steric hindrances and with additional donor atoms on the ligands. A systematic analysis was conducted by varying the ESI instrumental parameters (voltages, temperatures) to identify the best conditions for the analysis of this class of compounds. Furthermore, particular attention was paid to the study of the best solvent to be employed, considering the possible occurrence of alcoholysis and decomplexation phenomena. © IM Publications LLP 2013 All rights reserved.

New ambient temperature liquid calcium alkoxides, [Ca(O(CH 2CH2O)3CH3)2] (1) and [Ca(O(CH2CH2O)3CH2CH 3)2] (2), together with [Ca(OCH2C(CH 3)3)2] (3), were synthesised by reaction of ammonia-activated calcium with the appropriate alcohol. Their potentiality as stone consolidant products was investigated and compared with those of other alkoxides: [Ca(OCH2CH3)2(CH3CH 2OH)4] (4), [Ca(OCH3)2] (5), [{Ca(OCH2CH2OCH3)2}9] (6), already described in the literature. Reaction of 1-3 with the atmosphere was studied, final products analysed and kinetic pathways investigated. The reaction produces CaCO3 and the vaterite/calcite ratios observed in the coatings generated from isopropyl alcohol solutions of 1-6 were found to considerably vary with the alkoxide precursor, which has a strong influence also on the morphology of the produced films. Furthermore, their efficiency as stone consolidants was tested by ultrasound measurements.