During conservation treatment, consolidants and deacidifying agents can be added to the canvas of a painting to mechanically stabilise it and counteract the acidity that promotes degradation. In this study, new stabilising consolidants and deacidifying agents based on different nanoparticles (silica, calcium carbonate, magnesium oxide, cellulose nanofibrils and cellulose nanocrystals) were tested in comparison to traditionally used products. These products were applied onto different types of canvasses, and colour, gloss and pH changes were analysed. Conservators' subjective perceptions on the ease of application and the final visual results of the products were also assessed. Specifically, conservators were asked to examine the drying time and the ease of use of the products, as well as any changes in stiffness, darkening or whitening caused by the products on the canvasses. The best products were the ones based on calcium carbonate, magnesium oxide and cellulose nanocrystals. Cellulose nanofibrils are also promising consolidants because they are highly compatible with the chemical nature of painting canvasses.

This study evaluates the effectiveness of microblasting with powdered cellulose for the dry-cleaning of canvases. Various surface cleaning tests were conducted by microblasting on the reverse of canvas paintings and the results were compared to those obtained with traditional dry-cleaning techniques using erasers and sponges. To assess cleaning effectiveness and potential changes on the support, the treated surfaces were examined both before and after cleaning using optical microscopy (OM), scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM–EDX), confocal laser microscopy with surface roughness measurements, and spectrophotometry. The results from this comparative evaluation suggest that microblasting with powdered cellulose is a feasible technique for removing soiling on canvas and that it does not affect canvas structure or its topography. Furthermore, powdered cellulose leaves fewer particles of residues on the surface after cleaning, and these residues are chemically stable and compatible with the canvas support. Thus, the technique also avoids the potential negative long-term effects of eraser and sponge residues of particles that may remain on the canvas when these traditional systems are used.

A partir de datos inéditos obtenidos del estudio del sistema constructivo del soporte de madera se confirma que el frontal de san Cristóbal y los laterales de altar de Toses, actualmente expuestos separadamente y custodiados por el Museu Nacional d’Art de Catalunya (MNAC), forman un conjunto que originalmente guarnecía el altar principal de la iglesia de San Cristóbal de Toses (Ripollés, Cataluña). Estas obras, a pesar de su misma procedencia, han generado históricamente disparidad de opiniones acerca de la posibilidad de haber formado un único conjunto en origen, debido a la diferencia evidente de la calidad de la iconografía representada. Se trata de un hallazgo especialmente relevante dado que es el primer y único conjunto de frontal y laterales de altar del gótico lineal catalán conservado en la actualidad.

To protect a canvas easel painting, a common conservation strategy is to add a back plate at the stretcher, creating a closed air void. This plate protects not only from dust but mainly from temperature and relative humidity (RH) variations in the room and moisture changes in the wall on which it is hanging. The addition of hygroscopic layers can reduce the amplitude and change phase of humidity oscillations. This paper proposes a new mathematical model that can be used to predict moisture levels within the canvas when this conservation strategy is applied. The model is compared against the temperature and RH detailed experimental data, captured and shown in the latest paper by Padfield et al. Back protection of canvas painting. Our paper presents values of T, RH and mixing ratio (MR) obtained at the different layers of an easel painting, protected and unprotected, with cotton and without it, submitted to different room and wall temperature and RH cycles. The experimental results show a phase displacement between the canvas temperatures and the corresponding RH values in the canvas air boundary layer. In some cases this phase shift, which is an unexpected behaviour, allows RH and temperatures to achieve their maximum value at the same time. The purpose of the model is to simulate the RH response at the different air boundary layers inside the air void, such as the canvas, the aluminium back plate, and the hygroscopic cotton protection, produced by cyclic variations of temperature in the room or the wall. The model is built simulating four interrelated processes: the canvas permeation flow, the air infiltration rate between room and void, the equilibrium moisture content (EMC) and the vapour sorption rate for the canvas and the cotton. A key innovation of the model is the dependence between EMC, sorption rate, and RH condition, which captures the counter-intuitive behaviours observed in the data. The model results agree with the experimental results. The developed tool allows the interpretation of the processes involved and to extend the simulations to other cases, materials, and conditions.

Este estudio confirma que el frontal de santa Eugenia (MAD 121, París) y los laterales de Ribes (MEV, 9494/9495) formaban un conjunto que originalmente guarnecía el altar principal de la iglesia románica de santa Eugenia de Saga (Cerdaña, Cataluña). Al conjunto se le perdió el rastro tras la venta del frontal a un anticuario francés en 1896. Frontal y laterales no se habían vuelto a poner en relación debido a las diferencias de la policromía y a su supuesta procedencia distinta hasta la realización de esta investigación. Las evidencias han sido halladas mediante el análisis científico del soporte y el estudio de los vestigios de policromía conservados en los marcos de las tres obras. Esta es la segunda vez que se ha demostrado la unidad de un conjunto de altar del período del gótico lineal a partir del estudio del soporte, hecho que pone de relieve la importancia de los estudios técnicos de conservación-restauración.