Microscopic observations to track the behaviour of cyclododecane crystallisation and the effect of crystal formation on fragile porous substrates

This paper is published in the book ‘Subliming Surfaces: Volatile Binding Media in Heritage Conservation’, ed. Christina Rozeik (University of Cambridge Museums, 2018), pp. 67-78.The objective of this project is to observe the formation and changing structure of CDD crystals and their effect on painted porous surfaces. To investigate the interaction of CDD with absorbent and weak substrates, mock-ups of fragile painted plaster were prepared and CDD was applied to each of the mock-ups as either a hot melt or dissolved in Stoddard solvent. Time-lapse microphotography recorded the behaviour of the CDD crystals regularly over a span of six weeks. Scanning electron microscopy and confocal microscopy were utilised before application and after sublimation of CDD to characterise the surface morphology and porosity of the substrate, and to observe any damage that the CDD crystals may have caused to the surface of the artefact. Three computations were used in conjuction with confocal microscopy in order to analyse the topographic deviations caused by CDD interaction: surface subtraction, profile extraction, and horizontal contour extraction. It was concluded that CDD may be altering the original surface of the samples by widening pre-existing cracks, altering particle morphology, and inducing minor elevation changes in the overall topography. However, it does not impart a new texture to the plaster nor does it appear to cause new or original cracks in the substrate

Mechanical and physical characterization of natural and synthetic consolidants

Abstract The mechanical behavior of adhesives is strongly influenced by a large number of variables, relating to a complex interaction of mechanical-physical-chemical factors, such as its loading direction (shear, peel), the temperature and the environmental relative humidity (RH). These variables can have a large influence on the durability of restored art objects where thermoplastic adhesives have been used as a consolidant. This study aims to characterise the mechanical and physical behavior of some adhesives commonly used polymers by conservators as consolidants to restore cultural objects such as canvas paintings or historic wooden furniture. Twelve commercially available natural and synthetic adhesive materials were tested. The influence of RH at room temperature on the mechanical and physical properties of the adhesives was investigated. Shear and peel experiments were performed on adhesively bonded wood and canvas coupon to establish mechanical characterisation. The physical properties of the adhesives were determined by performing moisture adsorption measurements and Differential Scanning Calorimetry (DSC). The results of this study demonstrate that synthetic adhesive products are able to resist higher shear and peel loads than natural types. Moreover, the influence of important changes in RH on the mechanical properties of the adhesives was demonstrated. Reflecting on the combined data derived from shear and peel tests with the adhesive's sensitivity to moisture will help conservators to select the most suitable adhesives for their applications to achieve optimal durability and the best mechanical performance in versatile environmental conditions

Obtaining cross-sections of paint layers in cultural artifacts using femtosecond pulsed lasers

Recently, ultrafast lasers exhibiting high peak powers and extremely short pulse durations have created a new paradigm in materials processing. The precision and minimal thermal damage provided by ultrafast lasers in the machining of metals and dielectrics also suggests a novel application in obtaining precise cross-sections of fragile, combustible paint layers in artwork and cultural heritage property. Cross-sections of paint and other decorative layers on artwork provide critical information into its history and authenticity. However, the current methodology which uses a scalpel to obtain a cross-section can cause further damage, including crumbling, delamination, and paint compression. Here, we demonstrate the ability to make controlled cross-sections of paint layers with a femtosecond pulsed laser, with minimal damage to the surrounding artwork. The femtosecond laser cutting overcomes challenges such as fragile paint disintegrating under scalpel pressure, or oxidation by the continuous-wave (CW) laser. Variations in laser power and translational speed of the laser while cutting exhibit different benefits for cross-section sampling. The use of femtosecond lasers in studying artwork also presents new possibilities in analyzing, sampling, and cleaning of artwork with minimal destructive effects

When a test is more than just a test: Findings from patient interviews and survey in the trial of a technology to measure antidepressant medication response (the PReDicT Trial)

BackgroundA RCT of a novel intervention to detect antidepressant medication response (the PReDicT Test) took place in five European countries, accompanied by a nested study of its acceptability and implementation presented here. The RCT results indicated no effect of the intervention on depression at 8 weeks (primary outcome), although effects on anxiety at 8 weeks and functioning at 24 weeks were found.MethodsThe nested study used mixed methods. The aim was to explore patient experiences of the Test including acceptability and implementation, to inform its use within care. A bespoke survey was completed by trial participants in five countries (n = 778) at week 8. Semi-structured interviews were carried out in two countries soon after week 8 (UK n = 22, Germany n = 20). Quantitative data was analysed descriptively; for qualitative data, thematic analysis was carried out using a framework approach. Results of the two datasets were interrogated together.OutcomesSurvey results showed the intervention was well received, with a majority of participants indicating they would use it again, and it gave them helpful extra information; a small minority indicated the Test made them feel worse. Qualitative data showed the Test had unexpected properties, including: instigating a process of reflection, giving participants feedback on progress and new understanding about their illness, and making participants feel supported and more engaged in treatment.InterpretationThe qualitative and quantitative results are generally consistent. The Test's unexpected properties may explain why the RCT showed little effect, as properties were experienced across both trial arms. Beyond the RCT, the qualitative data sheds light on measurement reactivity, i.e., how measurements of depression can impact patients

Mechanical and physical characterization of natural and synthetic consolidants

The mechanical behavior of adhesives is strongly influenced by a large number of variables, relating to a complex interaction of mechanical-physical-chemical factors, such as its loading direction (shear, peel), the temperature and the environmental relative humidity (RH). These variables can have a large influence on the durability of restored art objects where thermoplastic adhesives have been used as a consolidant. This study aims to characterise the mechanical and physical behavior of some adhesives commonly used polymers by conservators as consolidants to restore cultural objects such as canvas paintings or historic wooden furniture. Twelve commercially available natural and synthetic adhesive materials were tested. The influence of RH at room temperature on the mechanical and physical properties of the adhesives was investigated. Shear and peel experiments were performed on adhesively bonded wood and canvas coupon to establish mechanical characterisation. The physical properties of the adhesives were determined by performing moisture adsorption measurements and Differential Scanning Calorimetry (DSC). The results of this study demonstrate that synthetic adhesive products are able to resist higher shear and peel loads than natural types. Moreover, the influence of important changes in RH on the mechanical properties of the adhesives was demonstrated. Reflecting on the combined data derived from shear and peel tests with the adhesive's sensitivity to moisture will help conservators to select the most suitable adhesives for their applications to achieve optimal durability and the best mechanical performance in versatile environmental conditions.Adhesion InstituteBio-based Structures & Material

Conservation Science Education Online (CSEO) – A heritage science resource

Conservation Science Education Online (CSEO) is a new online resource that shares strategies for teaching science in art conservation and related cultural heritage fields. An overview will be given of how undergraduate chemistry curricula in the United States have used examples from cultural heritage. The field of art conservation will then be described with an emphasis on the science curricula taught in art conservation programs around the world. Challenges include relating theoretical learning to real-world applications and teaching scientific terminology and concepts to students who may have limited science backgrounds; as well, there is a lack of textbooks and resources with appropriate case studies. The newly launched CSEO online resource offers freely available, effective teaching methods in the form of modules developed by international educators in the field. The inaugural CSEO Conference 2022 served as an introduction to the online resource for a global audience and was the first dedicated conference to bring together heritage science educators to discuss challenges and teaching strategies with the goal of building such a resource. The conference facilitated discussions among participants about teaching strategies, with the intention that these topics would become modules for the online resource, available to all science educators