Christian Degrigny

Haute Ecole Arc, Neuchâtel, Switzerland · Conservation-restauration

This paper examines two new methodological approachesexploring Reflectance Transformation Imaging (RTI) dataprocessing for detecting, documenting, and tracking surfacechanges. The first approach is unsupervised and applies per-pixel calculations on the raw image stack to extract informationrelated to specific surface attributes (angular reflectance...

This paper describes the development and application of a novel supervised segmentation technique used for conservation documentation based on visible appearance changes of Cultural Heritage (CH) metal surfaces. The technique is based on employing a linear discriminant analysis model to classify Reflectance Transformation Imaging (RTI) reconstructi...

Imaging techniques, along with their subsequent processing and analysis, are of utmost importance in the visual documentation of conservation processes of cultural heritage (CH) objects. Amongst them, Reflectance Transformation Imaging (RTI) is being used as a tool for the enhancement of surface topography, such as decorative details. This paper pr...

Artworks made of silver-based alloys tarnish unevenly, which considerably compromises their surface appearance as well as their historical and artistic value. Mechanical and chemical cleaning methods remove silver tarnish but in some cases are difficult to control. Electrolytic processes, which are often preferred because they retain some of the...

Corrosion of aluminum alloys is frequently observed in the cooling systems of functional vehicles dating from 1920 to 1940 in the Musée National de l’Automobile in Mulhouse, France. This paper shows how DiscoveryMat, a freeware analytical tool, has been successfully used for the in situ analysis of the materials concerned. The tool is based on the...

By visually inspecting the corrosion products of metal objects, conservators propose, on the basis of their experience and consultation of specialized literature, a first diagnosis. The online computer application MiCorr (micorr.org) follows this path while optimizing it. Using a graphical user interface, the MiCorr user constructs a digital strati...

L’aluminium et les alliages d’aluminium, matériaux récents, sont peu étudiés dans le cadre de de la conservation et de la restauration. Aussi les protocoles, en cas d’altération, sont rares et imprécis. Le « parcours patrimonial » de l’aluminium, présenté sous le prisme des transports (automobiles, aéronautiques et maritimes), et l’étude de cas par...

Multi-light acquisitions and modeling are well-studied techniques for characterizing surface geometry, widely used in the cultural heritage field. Current systems that are used to perform this kind of acquisition are mainly free-form or dome-based. Both of them have constraints in terms of reproducibility, limitations on the size of objects being a...

Le blanc de plomb est constitué de deux carbonates de plomb, la cérusite et l’hydrocérusite. Utilisé comme pigment de peinture et comme ingrédient cosmétique, il était synthétisé par corrosion de plomb métallique en présence de vinaigre et d’un apport extérieur en dioxyde de carbone (CO2), produit le plus souvent par du fumier de cheval. Ces deux r...

Toute intervention de conservation-restauration (CR) sur des métaux patrimoniaux requiert un diagnostic le plus exact possible. A partir de leur état de conservation, on cherche à comprendre les causes et les mécanismes ayant entraîné les altérations observées. La composition des matériaux et l’agressivité des environnements auxquels ils sont expo...

the absolute dating of paintings is crucial for tackling the problem of fake art. investigations to authenticate paintings rely on an advanced knowledge of art history and a collection of scientific techniques. Radiocarbon dating is the only technique that gives access to an absolute time scale, but its application is limited to organic materials s...

Augmented reality is currently being tested at château de Germolles- the residential palace of Duchess of Burgundy Margaret of Flanders, wife of Philip the Bold- to help the general public visualise the outcomes of the latest researches on the medieval mural paintings that were rediscovered in the 1970s and partly restored in 1989-1995. The mural d...

Imaging techniques were used to document and monitor physical damage to the unique wall paintings at the Château de Germolles, Burgundy, France. Photogrammetry combined with scanning are the most appropriate techniques to monitor the evolution of microcrack networks in the cornice overhanging the paintings and preserved as a witness to 19th century...

The absolute dating of paintings is crucial for tackling the problem of fake art. Investigations to authenticate paintings rely on an advanced knowledge of art history and a collection of scientific techniques. Radiocarbon dating is the only technique that gives access to an absolute time scale, but its application is limited to organic materials s...

L'application MiCorr vise à aider les professionnels de la conservation-restauration à réaliser le diagnostic le plus juste possible sur les métaux patrimoniaux qu'ils étudient. Sur la base d'observations visuelles et donc non invasives des formes de corrosion développées, retranscrites sous MiCorr à l'aide d'un outil de construction de structures...

Une intervention de conservation-restauration témoigne d'un niveau de savoir de l'oeuvre consi-dérée et de ses matériaux ainsi que d'un niveau d'expertise du professionnel impliqué. Aussi, on peut considérer qu'à ce temps donné, elle a été menée avec « les meilleures intentions ». Toute nouvelle connaissance acquise sur cette oeuvre et/ ou sur les...

The restoration of the Santa Vittoria reliquary conserved in the Diocesan Museum of Agrigento in Sicily at the Opificio delle Pietre Dure (OPD), Florence, was an opportunity to test various cleaning processes on its tarnished bust made of partly gilded silver plates. The mechanical/chemical protocols used at the OPD – calcium carbonate (CaCO3) or s...

Only recently (since the 1980s) have conservation professionals become interested in the conservation of the most modern of our heritage metals: aluminum. If the first aluminum alloys in the nineteenth century have good corrosion resistance and are usually well preserved, those produced in the twentieth century are often poorly conserved and requir...

The restoration of the Santa Vittoria reliquary conserved in the Diocesan Museum of Agrigento in Sicily at the Opificio delle Pietre Dure (OPD), Florence, was an opportunity to test various cleaning processes on its tarnished bust made of partly gilded silver plates. The mechanical/chemical protocols used at the OPD – calcium carbonate (CaCO3) or s...

The conservation of archaeological and historical metal artefacts requires a thorough diagnosis of their condition based on an understanding of the composition of the remaining metal components and their associated corrosion products. MiCorr is an online decision support system (DSS) for the local diagnosis of heritage metals developed within Haute...

Despite their presence in many museum collections as testimony to the great technological advances of the late 19th century, aluminium alloy objects are rarely exhibited or may even be discarded because of their unattractive surface appearance. Conservation professionals are often helpless when faced with these materials which they consider to be u...

In the past, many objects in the collection of the National Museum of Slovenia were severely damaged due to electrolytic/electrochemical cleaning. In the early 1990s, the decision was made to abandon this kind of treatment due to its harshness, although at the time important developments in electrolytic/electrochemical cleaning were underway in Eur...

There are different expressions of Cultural Heritage, from material to intangible heritage, whereas the term Cultural Heritage many times encompasses the main category of immovable Cultural Heri-tage (buildings, monuments, archaeological sites...). All over Europe, Heritage Buildings (HBs) attract millions of visitors every year. Being a part of pa...

Integration of heritage buildings and sites in their surroundings • Public Report Coordinator: Christian Degrigny Authors: Alice Tavares, Borgarino, Shirley Cefai, José Eloy Hortal Muñoz, Ilze Irbe, Maria Leus, Shu-Ling Lu, Anna Lobovikov-Katz, Marko Marinkovic, João Martins, Luisa Migliorati, Massimo Migliorini, Petros Patias, Veronika Shendova, S...

Integration of heritage buildings and sites in their surroundings • Public Report Coordinator: Christian Degrigny Contributors: Alice Tavares, Paola Borgarino, Shirley Cefai, José Eloy Hortal Muñoz, Ilze Irbe, Maria Leus, Shu-Ling Lu, Anna Lobovikov-Katz, Marko Marinkovic, João Martins, Luisa Migliorati, Massimo Migliorini, Petros Patias, Veronika...

In conservation of cultural heritage (CCH), experts from diverse areas of knowledge work together, each of them contributing unique expertise. However, in modern dynamic multi- and interdisciplinary collaboration, new contributors often remain conservation outsiders, being deeply submerged in their own research areas with regard to their research m...

Study of the minor and trace element contents in the composition of early aluminium is interesting from a cultural history perspective because it can provide information on the evolution of aluminium smelting practice. A range of aluminium artefacts from the Swiss National Museum and the Lausanne Historical Museum, Switzerland, have been characteri...

In this unique collection the authors present a wide range of interdisciplinary methods to study, document, and conserve material cultural heritage. The methods used serve as exemplars of best practice with a wide variety of cultural heritage objects having been recorded, examined, and visualised. The objects range in date, scale, materials, and st...

In this unique collection the authors present a wide range of interdisciplinary methods to study, document, and conserve material cultural heritage. The methods used serve as exemplars of best practice with a wide variety of cultural heritage objects having been recorded, examined, and visualised. The objects range in date, scale, materials, and st...

To help metal conservators search for corrosion forms and find treatment protocols, this paper describes the augmentation of the MIFAC-Metal project through its migration to the internet and the addition of the MiCorr Decision Support System (DSS). The new online version of MIFAC-Metal enables conservators to digitally construct stratigraphies that...

The Pleco is an open-source electrolytic pencil that can be used for the local treatment of metal components in inseparable metal-organic composite artefacts. It is low-cost, easy to use and self-built from a kit. It was initially developed to clean tarnish from silver plates nailed to wooden cores in reliquaries. This paper presents two case studi...

Aluminium alloys were first used in the middle of the 19th century to produce luxury artefacts. Later these light materials were employed to fabricate artefacts that became icons of our modern societies (Piccadilly Circus Eros, cap of the Washington Monument) before becoming the favourite materials of newly emerging industries (aeronautics, packagi...

Collections of scientific and technical artefacts have a heritage value that is intricately linked to their industrial, economic, social and cultural context. When separated from their functional environment, they can suffer from de-contextualization and loss of significance. The OBS project aimed at developing an analytical method for the study an...

Technical, scientific and horological (STH) heritage artefacts are particular. They are often complex (their function and use might not be easy to understand at first glance) and sometimes unique (prototypes). Minimal intervention is rarely applicable when aiming at restoring their function. Therefore, their conservation-restoration requires a part...

To help metal conservators search for corrosion forms and find treatment protocols, this paper describes the augmentation of the MIFAC-Metal project through its migration to the internet and the addition of the MiCorr Decision Support System (DSS). The new online version of MIFAC-Metal enables conservators to digitally construct stratigraphies that...

Metal conservators confronted with unknown artefacts rely on previous literature to develop treatment protocols. This search can be tedious given the dissemination of information across corpus of unstructured texts, mainly in the form of research papers and semi-structured databases of artefacts. In order to improve the search of artefacts sharing...

The Château de Germolles is one of the rare palaces in France dating from the 14th century. The noble floor is decorated with wall paintings that are a unique example of courtly love spirit that infused the princely courts of the time. After being concealed sometime in the 19th century, the paintings were rediscovered and uncovered in the middle of...

Metal diagnosis of heritage objects is a difficult task performed by conservators, mainly due to the fact that invasive techniques are not allowed on these artifacts. Therefore, conservators have developed diagnosis methods based on the observation of the corrosion forms of the objects. However, although these methods are useful to share a common r...

Re-contextualisation of objects from the Neuchâtel Observatory

Metal diagnosis of heritage objects is a difficult task performed by conservators, mainly due to the fact that invasive techniques are not allowed on these artifacts. Therefore, conservators have developed diagnosis methods based on the observation of the corrosion forms of the objects. However, although these methods are useful to share a common r...

Various electrochemical measurement techniques (polarization, electrochemical impedance spectroscopy [EIS], and electrochemical quartz microbalance [EQCM]) and accelerated corrosion tests were used to show that phosphates can be used as iron corrosion inhibitors in 20% polyethylene glycol (PEG 400) solutions. Their action mechanisms were found to m...

The prototyping of a newly designed electrolytic pencil for the local cleaning of silver tarnish on artifacts comprising inseparable organic components is described. The pencil helps determine the type and amount of tarnish, define the cleaning parameters (treatment potential and duration), and provides a safe and efficient way to locally and elect...

A presentation of the conservation approach to clean tarnished silver based artefacts from Saint-Maurice Abbey treasury

The Pleco, a new electrolytic pencil, was used for the local cleaning of silver plates nailed to the wooden core of the reliquary head of Saint Candide, one of the masterpieces in the Treasury of Saint-Maurice Abbey, Valais (Switzerland). The versatility of the tool is demonstrated in terms of its ability to precisely determine the type and amount...

Colour and Space in Cultural Heritage (www.COSCH.info) is a transdomain European Action (TD1201) in the area of Materials, Physics and Nanosciences (MPNS). The Action runs from 2013 to 2017 and benefits from the support of the European Cooperation in Science and Technology http://www.cost.eu/domains_actions/mpns/Actions/TD1201. The Authors are acti...

The paper introduces some key interdisciplinary questions concerning the development of optical measuring techniques and electronic imaging applied to documentation and presentation of artefacts, as identified through the work of Colour and Space in Cultural Heritage (www.COSCH.info), a trans-domain European Action (TD1201) in the area of Materials...

Silver artefacts exposed indoor in uncontrolled environments often show an unpleasant heterogeneous tarnish. In the absence of any cleaning procedures adapted to these localised forms of corrosion, tarnished silver is usually cleaned electrolytically by full immersion. When organic materials are associated to these metallic elements within composit...

Development of the Pleco electrolytic pencil

Annex of the internal report

Database of Swiss corrosion models - preliminary steps of the MiCorr application

Development of the Discovery-Mat application to analyse metals using Ecorr versus time measurements _ follow up of the SPAMT-Test project

Testing different protection systems for steel and brass exposed to uncontrolled environments

Use of Ecorr measurements to analyse copper based alloys

New protection systems for cultural heritage artefacts can be tested and their efficiency, compared to traditional systems, assessed using artificial metal coupons. The manufacturing of these coupons requires though a thorough investigation of the artefacts that they are supposed to simulate. Not only their composition, but their surface preparatio...

Two non-toxic corrosion inhibitors in a solution elaborated from a carboxylic acid were tested for the temporary protection of iron and copper alloy objects in the collections of the Historical Swiss Army Material Foundation (HSAM Foundation). These objects are stored in an uncontrolled environmental in storage facilities in or near Thun and Burgdo...

This paper describes an electrochemical tool developed to measure the corrosion potential of metal surfaces, often expressed as Ecorr, versus time, as a technique used in the qualitative analysis of copper alloys. The instrument is easy to use and transport, and is ideally adapted to the work of conservators during on-site condition survey. Along w...

This paper describes an electrochemical tool developed to measure the corrosion potential of metal surfaces, often expressed as Ecorr, versus time, as a technique used in the qualitative analysis of copper alloys. The instrument is easy to use and transport, and is ideally adapted to the work of conservators during on-site condition survey. Along w...

Localized electrolytic cleaning has been tested on a gilt silver artefact to remove its tarnish.

Localized electrolytic cleaning has been tested on a gilt silver artefact to remove its tarnish.

Marine artefacts are often excavated to prevent looting. Therefore conservation procedures must be appropriately planned & budgets adequate for the labour & resource intensive processes required to keep marine artefacts stable in their post-excavation environment. This poster describes a low-budget re-treatment of a 16th-17th century iron swivel gu...

A new analytical tool for copper alloys based on the monitoring of E corr vs time is presented. This tool is particularly adapted to condition surveys carried out on-site by conservators on historic objects and was optimised so to respond to the needs of the conservation field such as the minimal impact on the artefacts, the portability of the inst...