Notes to user
What you can find in the technical files
The results of this research are being shared in the Ensor Online Scholarly Catalogue (EOSC), which provides the public with access to the findings of the ERP. The research is ongoing, which means that new findings are continually being added to the EOSC. To date, we have carried out in-depth material and technical research on ten paintings. At the moment, we are focusing on the paintings from the KMSKA collection, but this will be extended to works from other collections in the future.
Among the paintings researched to date are a number of works from Ensor's early, realistic and rather dark period; some from his second, grotesque period, characterised by bright and contrasting colours, the inclusion of masks and skeletons and an overall lighter colour palette; and a few from his third or late period, characterised by a light but still contrasting use of colour, where he applied dilute and transparent paint mostly leaving the ground layer visible. 1 We hope that by doing so we can present an evolution in Ensor’s technique and use of materials.
Every painting is examined as thoroughly as possible, both from an art historical perspective, with an art historical summary of context, style and iconography, and with a technical file that describes the materials and techniques of the painting. Each file begins with a short identification of the work, listing its title, the year in which it was made, its inventory number, support, technique and dimensions. This is followed by art historical information about what is depicted (iconography), how it is depicted (style), what the purpose and function of the painting are, and how it was received and interpreted. The art historical explanation is followed by the technical part, which begins with a short summary of the technical file. This short text lists the research results briefly and concisely.
The technical part is supported by research images. For this purpose, we use an IIIF viewer with high-resolution images of the works in visual light, raking light, UV light and infrared light as well as in x-ray. This viewer makes it possible to display and compare images side by side. As well as zooming in and out, which offers an interactive way of discovering information about the work.
The actual research findings are listed in the Materials and techniques section. Every painting is described in the same way, examining the painting layer by layer. It starts with the support, describing whether the painting is painted on a stretched canvas, cardboard or panel and what the particular characteristics of the support are (labels, damage, original parts or not, and in the case of canvas, tensioning method). This is followed by a description of the ground layer, in terms of composition, thickness, colour, condition and visibility. Ensor often used lead white grounds which are sometimes beige-tinted and sometimes not. From time to time, he added a (zinc) white paint layer on top of this ground, probably to modify its colour.
After that, we look for the presence of a carbon-based underdrawing, which is a sketch of the initial composition. This is researched both visually and on infrared images. Ensor did not always sketch out his composition in pencil or chalk, but frequently made painted sketches instead. The section on the paint layer is split under several sub-headings. It begins with a description of the technique, followed by a description of the materials used to apply the paint, after which we list the pigments used, and lastly, we describe the signature. This is followed by a description of any damage and restorations.
The varnish section describes the presence or absence of varnish, how this was applied, the materials it was made of, and its current condition.
The History of the Painting is divided under three separate subheadings. Under Acquisition History, we provide information about the provenance of the work and how it entered the KMSKA collection. All restorations and condition reports are listed under Restoration History including information about all interventions and findings (or a summary thereof). Under Exhibition History all the exhibitions in which the painting has been displayed are listed in chronological order.
Navigating the catalogue
The Online Scholarly Catalogue is organised according to a research project, and these are linked in turn to an artist. This allows search and navigation features to be specifically tailored to research needs. The Ensor Research project is currently being made public. All the navigation pages can be found on the landing page, namely the Introduction, Acknowledgements, Notes to reader, Glossary, Bibliography and Copyright. All the research files are listed on this page with a thumbnail of the artwork, its title, publication date, date and dimensions. One way of searching for information is to click on a file. You will then be immediately shown the art history essay, the technical research, the research images and footnotes.
A second way of searching is by using ‘Search in Catalogue’. This search feature uses several specific filters. A combination of filters ensures a more accurate search, so we chose not to include a search bar for free searches. The search filters can be combined in different ways. You may search according to general category (such as support, type, colour), by technical aspect (such as condition, restoration process), or by research image type (image spectrum). You can type a search term into a search filter.
There is also a glossary of frequently used terms. These terms are also highlighted in the text. If you click on the term in the text, a definition will appear; you can also click through to the full glossary. Whenever possible, you can click on the glossary-term in the list to navigate to the Arts and Architecture Thesaurus (AAT).
The Online Scholarly Catalogue uses a Mirador IIIF viewer. This offers the following features: zooming in and out and opening different images alongside one another to compare images. Therefore, click on the plus sign in the top right-hand corner. You can open already existing images in the viewer or you can add a new IIIF-image by clicking on 'add resource' in the bottom right corner. A separate viewer shows the entire artwork and all the research images made of it in all the different image spectra. The images in the texts can also be opened in the viewer.
Techniques used
Stylistic research
The stylistic research of paintings is the analysis of the visual style of the artist. This includes matters like the artist’s use of colour, brushwork, composition and subject matter. This provides an understanding of how the artist approached his work and reveals how his style evolved over the passage of time.
Visual research
Visual research is an essential part of painting research, both with the naked eye and under magnification with a headset magnifier or stereomicroscope. This visual research makes it possible to study any zones of interest on a painting closely and provides an initial understanding of the condition of the work, the materials, techniques used to make it, and the way it was constructed.
Stereomicroscope
During visual research it is often helpful to view the paint layer under magnification. We can do this with a stereomicroscope. This is a microscope placed on a studio stand so it is easy to position in front of the painting. We used a SZ-40 Olympus stereomicroscope with GSWH 10X/22 eye pieces. This allows between 6.7 x and 40 x magnification. A Leica MC 170 HD digital camera was mounted on the microscope and was used with Leica Application Suite (LAS) software.
3D microscope
The 3D microscope is a digital microscope that is able to zoom in closely on the paint layer and make high-resolution images of very small details of paintings. It is even possible to create 3D images of certain areas, making the topography of the paint layer visible, and providing a better understanding of the stratigraphy or build-up of layers. This microscope is mounted on an x and y axis to allow large areas to be scanned in detail.
This microscope allows us to look at minute details of paintings, such as brushstrokes, craquelure (cracks in the paint), damage and deterioration. As a result, the microscope allows us to see things that we would miss if were we only to look with the naked eye.
We used the Hirox 3D Digital Microscope for this research. The system is placed on an X-Y-Z software-controlled motorised stand with a range of 50 cm x 50 cm and 8 cm on the Z axis. We used the telecentric Ultra-High Resolution Motorised Zoom Lens (HR-1020E) with 10x, x30 and x90 magnification and an AC-1020P polarising filter, the HR-2500(E) with 20x to 2500x magnification and the HR-2016(E) lens with 6x-320x magnification. The paintings were studied in normal light, as well as under raking light and UV. 2
Raking light
Paintings can be studied and photographed under raking light. A light source is placed at one side of the work, at an oblique angle to the painting’s surface. This causes the light to ‘rake’ the surface, creating strong shadows. This sort of lighting reveals subtle variations in height in the paint layer and helps document the topography of the paint layer and support. This makes it easier to see patterns of damage and undulations, old restorations and the artist’s techniques than in visual light. In this way, impastos, strong craquelure or distortions of the support become clearly visible. 3
Ultraviolet Induced Visual Fluorescence Photography (UIVFP) or Ultraviolet light (UV)
When we look at paintings under UV light, we do not see the UV itself – it is invisible to the naked eye – but rather the reflected visible light that arises through the interaction of the UV light and the materials in the painting. These emissions of visible light are called fluorescence and can be captured with UV photography. Not all materials fluoresce, but when they do, they often do so in a unique way. The various colours of fluorescence can therefore provide information about the presence of varnish layers and their manner of application, or the presence of old restorations and overpaintings. It sometimes tells us something about the pigments used and whether or not these have deteriorated too. 4
Infrared Photography
This technique is used to render the underdrawings of paintings visible. Infrared light is used for this. It is invisible to the naked eye and has a longer wavelength than visible light, therefore penetrating deeper into the painting. Infrared can penetrate through most of the upper paint layers, is reflected by the ground layer and absorbed by carbon-based materials, like pencil drawings. This creates a contrasting black-and-white image that makes the underdrawing visible. Infrared photography can also reveal changes in the composition and old damage and repairs. Infrared reflectography uses longer wavelengths than infrared radiation, which means they penetrate certain layers of paint even better. As a result, carbon-based underdrawings can often be visualised even better. However, the drawback is that the resolution of this technique is often less good, and the images created are often blurry. 5
Infrared False Colour
Infrared False Colour is a technique used to help the eye distinguish between various shades of grey. It starts from the monochrome infrared photo or infrared reflectogram. The information contained in these infrared images is combined with a normal colour photograph to create a ‘false colour image’. It is essential that both images are taken from exactly the same position. In Adobe Photoshop, the blue channel of the colour photograph is replaced by the monochrome infrared image. This brings out any nuances in the grey of the monochrome infrared image and makes it easier to distinguish between materials. Certain pigments have unique characteristics in the infrared spectrum and can therefore be detected on false colour images. 6
X-ray
We are all familiar with X-rays from the medical world, where, for example, broken bones are visualised with x-rays. We can use this same technique to look through paintings to visualise their underlying structures and hidden characteristics without damaging the painting.
X-rays are invisible to the naked eye. When a painting is exposed to x-rays, different materials absorb these rays to different degrees, depending on their density and composition. This difference in absorption is recorded on an x-ray film or digital sensor, resulting in a black-and-white image. The white parts show high-density materials, while the black parts show low-density materials. This works well with paintings because up until the 19th century, lead white paint – a white lead-based pigment – was often used. Lead has a high atomic number (82) and therefore absorbs x-ray strongly. This gives rise to informative black-and-white images or x-rays.
Because x-rays go right through paintings, they provide detailed images of the underlying structures and enable the discovery of changes in composition, hidden (overpainted) paintings, damage and earlier restorations. It can also reveal things about the materials and techniques the painter used. 7
Portable X-Ray Fluorescence (pXRF)
pXRF is a non-destructive, analytical technique used to detect the chemical elements of materials. pXRF is a portable, handheld device, that emits x-rays. The x-rays are directed at a point on the painting, interact with the materials in the paint layer and send back a second ray. The device captures and analyses this to obtain a spectrum of measurements of all the chemical elements in the paint layer. These measurements allow us to figure out which pigments have been used for the painting. The measurements provide the chemical composition of all the paint layers at the point where the measurement is taken, but it is not possible to distinguish between the different layers. As a result, pigment use is sometimes difficult to determine if the paint layers are mixed or if there are many superimposed layers of paint. If we detect both copper and arsenic in a green paint layer, it could be either Emerald or Scheele’s green. Therefore, this technique does not actually identify the pigments themselves, but simply provides an indication of which pigments are likely to have been used. It cannot provide information about organic pigments either. 8
If you would like to learn more about this technique and the results of pXRF research on Ensor’s paintings, please consult Geert Van der Snickt, ‘James Ensor’s Pigments studied by means of portable and Synchrotron Radiation-based X-ray Techniques: Evolution, Context and Degradation,” (PhD diss, University of Antwerp, 2012)’, which provides a good overview of the evolution of Ensor’s pigment use.
Macro X-Ray Fluorescence (MA-XRF)
The MA-XRF scanner emits x-rays that are sent to the painting, interact with the materials in the paint layer and send a secondary ray back that is picked up by the scanner. The scanner measures the chemical composition of the paint layer on a point-by-point basis, and does this by scanning surfaces of approximately 57x60 cm with an automated, software-controlled X and Y axis. These scans result in several black-and-white images each showing the distribution of a single chemical element within the paint layer. 9 The white areas of the image show where a particular element was found; the black areas show where it was lacking. This provides an overview of where the various pigments were used. For example, the cobalt image will show where there is cobalt in the paint layer. Cobalt is often found in blue paint, indicated the use of cobalt blue in the painting. If mercury is detected in a red paint layer then we know that vermillion – a red pigment containing mercury – was used.
As x-rays penetrate more deeply into the paint layer, we also get information about aspects that are no longer visible to the naked eye, such as elements that have been overpainted. This technique allows us to digitally reconstruct compositions that have been overpainted. 10
The MA-XRF scans were performed with the University of Antwerp’s (AXIS and Arches research groups’) AXIL scanner, built in-house. This comprises a Vortex EX-90 SDD detector, a 50 W XOS tube with a rhodium (Rh) anode, carried out with 50 kV and 1 mA, with a spot size of 200 µm with a polycapillary lens. The data processing was carried out in PyMCA and DataMuncher.
