Tag Archives: art restoration

Non-invasive chemical imaging reveals the Eykian Lamb of God’s secrets

Left: color image after the 1950s treatment. The ears of the Eyckian Lamb were revealed after removal of the 16th-century overpaint obscuring the background. Right: color image after the 2019 treatment that removed all of the 16th century overpaint, revealing the face of the Eyckian Lamb. The dotted lines indicate the outline of the head before removal of 16th-century overpaint.

Fascinating, yes? More than one person has noticed that the ‘new’ lamb is “disturbingly human-like.” First, here’s more about this masterpiece and the technology used to restore it (from a July 29, 2020 University of Antwerp (Belgium) press release (Note: I do not have all of the figures (images) described in this press release embedded here),

Two non-invasive chemical imaging modalities were employed to help understand the changes made over time to the Lamb of God, the focal point of the Ghent Altarpiece (1432) by Hubert and Jan Van Eyck. Two major results were obtained: a prediction of the facial features of the Lamb of God that had been hidden beneath non-original overpaint dating from the 16th century (and later), and evidence for a smaller earlier version of the Lamb’s body with a more naturalistic build. These non-invasive imaging methods, combined with analysis of paint cross-sections and magnified examination of the paint surface, provide objective chemical evidence to understand the extent of overpaints and the state of preservation of the original Eyckian paint underneath.

The Ghent Altarpiece is one of the founding masterpieces of Western European painting. The central panel, The Adoration of the Lamb, represents the sacrifice of Christ with a depiction of the Lamb of God standing on an altar, blood pouring into a chalice. During conservation treatment and technical analysis in the 1950s, conservators recognized the presence of overpaint on the Lamb and the surrounding area. But based on the evidence available at that time, the decision was made to remove only the overpaint obscuring the background immediately surrounding the head. As a result, the ears of the Eyckian Lamb were uncovered, leading to the surprising effect of a head with four ears (Figure 1).

Figure 1: Left: Color image after the 1950s treatment. The ears of the Eyckian Lamb were revealed after removal of the 16th century overpaint obscuring the background. (© Lukasweb.be – Art in Flanders vzw). Right: Color image after the 2019 treatment that removed all of the 16th century overpaint, revealing the face of the Eyckian Lamb. The dotted lines indicate the outline of the head before removal of 16th century overpaint. (© Lukasweb.be – Art in Flanders vzw).

During the recent conservation treatment of the central panel, chemical images collected before 16th century overpaint was removed revealed facial features that predicted aspects of the Eyckian Lamb, at that time still hidden below the overpaint. For example, the smaller, v-shaped nostrils of the Eyckian Lamb are situated higher than the 16th century nose, as revealed in the map for mercury, an element associated with the red pigment vermilion (Figure 2, red arrow). A pair of eyes that look forward, slightly lower than the 16th century eyes, can be seen in a false-color hyperspectral infrared reflectance image (Figure 2, right). This image also shows dark preparatory underdrawing lines that define pursed lips, and in conjunction with the presence of mercury in this area, suggest the Eyckian lips were more prominent. In addition, the higher, 16th century ears were painted over the gilded rays of the halo (Figure 2, yellow rays). Gilding is typically the artist’s final touch when working on a painting, which supports the conclusion that the lower set of ears is the Eyckian original. Collectively, these facial features indicate that, compared to the 16th century restorer’s overpainted face, the Eyckian Lamb has a smaller face with a distinctive expression.

Figure 2: Left: Colorized composite elemental map showing the distribution of gold (in yellow), mercury (in red), and lead (in white). The red arrow indicates the position of the Eyckian Lamb’s nostrils. (University of Antwerp). Right: Composite false-color infrared reflectance image (blue – 1000 nm, green – 1350 nm, red – 1650 nm) shows underdrawn lines indicating the position of facial features of the Eyckian Lamb, including forward-gazing eyes, the division between the lips, and the jawline. (National Gallery of Art, Washington). The dotted lines indicate the outline of the head before removal of 16th century overpaint.

The new imaging also revealed previously unrecognized revisions to the size and shape of the Lamb’s body: a more naturalistically shaped Lamb, with slightly sagging back, more rounded hindquarters and a smaller tail. The artist’s underdrawing lines used to lay out the design of the smaller shape can be seen in the false-color hyperspectral infrared reflectance image (Figure 3, lower left, white arrows). Mathematical processing of the reflectance dataset to emphasize a spectral feature associated with the pigment lead white resulted in a clearer image of the smaller Lamb (Figure 3, lower right). Differences between the paint handling of the fleece in the initial small Lamb and the revised area of the larger Lamb also were found upon reexamination of the x-radiograph and the paint surface under the microscope.

Figure 3: Upper left: Color image before removal of all 16th century overpaint. (© Lukasweb.be – Art in Flanders vzw). Upper right: Color image after removal of all 16th century overpaint. (© Lukasweb.be – Art in Flanders vzw). Lower left: False-color infrared reflectance image (blue – 1000 nm, green – 1350 nm, red – 1650 nm) reveals underdrawing lines that denote the smaller hindquarters of the initial Lamb. Lower right: Map derived from processing the infrared reflectance image cube showing the initial Lamb with a slightly sagging back, more rounded hindquarters and a smaller tail. Brighter areas of the map indicate stronger absorption from the -OH group associated with one of the forms of lead white. (National Gallery of Art, Washington).

During the conservation treatment completed in 2019, decisions were informed by well-established conservation methods (high-resolution color photography, X-radiography, infrared imaging, paint sample analysis) as well as the new chemical imaging. In this way, the conservation treatment uncovered the smaller face of the Eyckian Lamb, with forward-facing eyes that meet the viewer’s gaze. Only overpaints that could be identified as being later additions dating from the 16th century onward were carefully and safely removed. The body of the Lamb, however, has not changed. The material evidence indicates that the lead white paint layer used to define the larger squared-off hindquarters was applied prior to the 16th century restoration, but because analysis at the present time cannot definitively establish whether this was a change by the original artist(s) or a very early restoration or alteration by another artist, the enlarged contour of the Lamb was left untouched.

Chemical imaging technologies can be used to build confidence about the state of preservation of original paint and help guide the decision to remove overpaint. Combined with the conservators’ thorough optical examination, informed by years of experience and insights derived from paint cross-sections, chemical imaging methods will no doubt be central to ongoing interdisciplinary research, helping to resolve long-standing art-historical issues on the Ghent Altarpiece as well as other works of art. These findings were obtained by researchers from the University of Antwerp using macroscale X-ray fluorescence imaging and researchers at the National Gallery of Art, Washington using infrared reflectance imaging spectroscopy, interpreted in conjunction with the observations of the scientists and the conservation team from The Royal Institute for Cultural Heritage (KIK-IRPA), Brussels.

A January 22, 2020 British Broadcasting Corporation (BBC) online news item notes some of the response to the ‘new’ lamb (Note: A link has been removed),

Restorers found that the central panel of the artwork, known as the Adoration of the Mystic Lamb, had been painted over in the 16th Century.

Another artist had altered the Lamb of God, a symbol for Jesus depicted at the centre of the panel.

Now conservationists have stripped away the overpaint, revealing the lamb’s “intense gaze” and “large frontal eyes”.

Hélène Dubois, the head of the restoration project, told the Art Newspaper the original lamb had a more “intense interaction with the onlookers”.

She said the lamb’s “cartoonish” depiction, which departs from the painting’s naturalistic style, required more research.

The lamb has been described as having an “alarmingly humanoid face” with “penetrating, close-set eyes, full pink lips and flared nostrils” by the Smithsonian Magazine.

These features are “eye-catching, if not alarmingly anthropomorphic”, said the magazine, the official journal of the Smithsonian Institution.

There was also disbelief on social media, where the lamb was called “disturbing” by some and compared to an “alien creature”. Some said they felt it would have been better to not restore the lamb’s original face.

The painter of the panel, Jan Van Eyck, is considered to be one of the most technical and talented artists of his generation. However, it is widely believed that The Ghent Altarpiece was started by his brother, Hubert Van Eyck.

Taken away by the Nazis during World War Two and Napoleon’s troops in the 1700s, the altarpiece is thought to be one of the most frequently stolen artworks of all time.

If you have the time, do read the January 22, 2020 BBC news item in its entirety as it conveys more of the controversy.

Jennifer Ouellette’s July 29, 2020 article for Ars Technica delves further into the technical detail along with some history about this particular 21st Century restoration. The conservators and experts used artificial intelligence (AI) to assist.

Here’s a link to and a citation for the paper,

Dual mode standoff imaging spectroscopy documents the painting process of the Lamb of God in the Ghent Altarpiece by J. and H. Van Eyck by Geert Van der Snickt, Kathryn A. Dooley, Jana Sanyova, Hélène Dubois, John K. Delaney, E. Melanie Gifford, Stijn Legrand, Nathalie Laquiere and Koen Janssens. Science Advances 29 Jul 2020: Vol. 6, no. 31, eabb3379 DOI: 10.1126/sciadv.abb3379

This paper is open access.

Rijksmuseum’s ‘live’ restoration of Rembrandt’s masterpiece: The Nightwatch: is it or isn’t it like watching paint dry?

Somewhere in my travels, I saw ‘like watching paint dry’ as a description for the experience of watching researchers examining Rembrandt’s Night Watch. Granted it’s probably not that exciting but there has to be something to be said for being present while experts undertake an extraordinary art restoration effort. The Night Watch is not only a masterpiece—it’s huge.

This posting was written closer to the time the ‘live’ restoration first began. I have an update at the end of this posting.

A July 8, 2019 news item on the British Broadcasting Corporation’s (BBC) news online sketches in some details,

The masterpiece, created in 1642, has been placed inside a specially designed glass chamber so that it can still be viewed while being restored.

Enthusiasts can follow the latest on the restoration work online.

The celebrated painting was last restored more than 40 years ago after it was slashed with a knife.

The Night Watch is considered Rembrandt’s most ambitious work. It was commissioned by the mayor and leader of the civic guard of Amsterdam, Frans Banninck Cocq, who wanted a group portrait of his militia company.

The painting is nearly 4m tall and 4.5m wide (12.5 x 15 ft) and weighs 337kg (743lb) [emphasis mine]. As well as being famous for its size, the painting is acclaimed for its use of dramatic lighting and movement.

But experts at Amsterdam’s Rijksmuseum are concerned that aspects of the masterpiece are changing, pointing as an example to the blanching of the figure of a small dog. The museum said the multi-million euro research and restoration project under way would help staff gain a better understanding of the painting’s condition.

An October 16, 2018 Rijksmuseum press release announced the restoration work months prior to the start (Note: Some of the information is repetitive;),

Before the restoration begins, The Night Watch will be the centrepiece of the Rijksmuseum’s display of their entire collection of more than 400 works by Rembrandt in an exhibition to mark the 350th anniversary of the artist’s death opening on 15 February 2019.

Commissioned in 1642 by the mayor and leader of the civic guard of Amsterdam, Frans Banninck Cocq, to create a group portrait of his shooting company, The Night Watch is recognised as one of the most important works of art in the world today and hangs in the specially designed “Gallery of Honour” at the Rijksmuseum. It is more than 40 years since The Night Watch underwent its last major restoration, following an attack on the painting in 1975.

The Night Watch will be encased in a state-of-the-art clear glass chamber designed by the French architect Jean Michel Wilmotte. This will ensure that the painting can remain on display for museum visitors. A digital platform will allow viewers from all over the world to follow the entire process online [emphasis mine] continuing the Rijksmuseum innovation in the digital field.

Taco Dibbits, General Director Rijksmuseum: The Night Watch is one of the most famous paintings in the world. It belongs to us all, and that is why we have decided to conduct the restoration within the museum itself – and everyone, wherever they are, will be able to follow the process online.

The Rijksmuseum continually monitors the condition of The Night Watch, and it has been discovered that changes are occurring, such as the blanching [emphasis mine] on the dog figure at the lower right of the painting. To gain a better understanding of its condition as a whole, the decision has been taken to conduct a thorough examination. This detailed study is necessary to determine the best treatment plan, and will involve imaging techniques, high-resolution photography and highly advanced computer analysis. Using these and other methods, we will be able to form a very detailed picture of the painting – not only of the painted surface, but of each and every layer, from varnish to canvas.

A great deal of experience has been gained in the Rijksmuseum relating to the restoration of Rembrandt’s paintings. Last year saw the completion of the restoration of Rembrandt’s spectacular portraits of Marten Soolmans and Oopjen Coppit. The research team working on The Night Watch is made up of researchers, conservators and restorers from the Rijksmuseum, which will conduct this research in close collaboration with museums and universities in the Netherlands and abroad.

The Night Watch

The group portrait of the officers and other members of the militia company of District II, under the command of Captain Frans Banninck Cocq and Lieutenant Willem van Ruytenburch, now known as The Night Watch, is Rembrandt’s most ambitious painting. This 1642 commission by members of Amsterdam’s civic guard is Rembrandt’s first and only painting of a militia group. It is celebrated particularly for its bold and energetic composition, with the musketeers being depicted ‘in motion’, rather than in static portrait poses. The Night Watch belongs to the city of Amsterdam, and it been the highlight of the Rijksmuseum collection since 1808. The architect of the Rijksmuseum building Pierre Cuypers (1827-1921) even created a dedicated gallery of honour for The Night Watch, and it is now admired there by more than 2.2 million people annually.

2019, The Year of Rembrandt

The Year of Rembrandt, 2019, marks the 350th anniversary of the artist’s death with two major exhibitions honouring the great master painter. All the Rembrandts of the Rijksmuseum (15 February to 10 June 2019) will bring together the Rijksmuseum’s entire collection of Rembrandt’s paintings, drawings and prints, for the first time in history. The second exhibition, Rembrandt-Velázquez (11 October 2019 to 19 January 2020), will put the master in international context by placing 17th-century Spanish and Dutch masterpieces in dialogue with each another.

First, the restoration work is not being livestreamed; the digital platform Operation Night Watch is a collection of resources, which are being updated constantly, For example, the first scan was placed online in Operation Night Watch on July 16, 2019.

Second, ‘blanching’ reminded me of a June 22, 2017 posting where I featured research into why masterpieces were turning into soap, (Note: The second paragraph should be indented to indicated that it’s an excerpt fro the news release. Unfortunately, the folks at WordPress appear to have removed the tools that would allow me to do that and more),

This piece of research has made a winding trek through the online science world. First it was featured in an April 20, 2017 American Chemical Society news release on EurekAlert

A good art dealer can really clean up in today’s market, but not when some weird chemistry wreaks havoc on masterpieces. Art conservators started to notice microscopic pockmarks forming on the surfaces of treasured oil paintings that cause the images to look hazy. It turns out the marks are eruptions of paint caused, weirdly, by soap that forms via chemical reactions. Since you have no time to watch paint dry, we explain how paintings from Rembrandts to O’Keefes are threatened by their own compositions — and we don’t mean the imagery.

….

Getting back to the Night Watch, there’s a July 8, 2019 Rijksmuseum press release which provides some technical details,

On 8 July 2019 the Rijksmuseum starts Operation Night Watch. It will be the biggest and most wide-ranging research and conservation project in the history of Rembrandt’s masterpiece. The goal of Operation Night Watch is the long-term preservation of the painting. The entire operation will take place in a specially designed glass chamber so the visiting public can watch.

Never before has such a wide-ranging and thorough investigation been made of the condition of The Night Watch. The latest and most advanced research techniques will be used, ranging from digital imaging and scientific and technical research, to computer science and artificial intelligence. The research will lead to a better understanding of the painting’s original appearance and current state, and provide insight into the many changes that The Night Watch has undergone over the course of the last four centuries. The outcome of the research will be a treatment plan that will form the basis for the restoration of the painting.

Operation Night Watch can also be followed online from 8 July 2019 at rijksmuseum.nl/nightwatch

From art historical research to artificial intelligence

Operation Night Watch will look at questions regarding the original commission, Rembrandt’s materials and painting technique, the impact of previous treatments and later interventions, as well as the ageing, degradation and future of the painting. This will involve the newest and most advanced research methods and technologies, including art historical and archival research, scientific and technical research, computer science and artificial intelligence.

During the research phase The Night Watch will be unframed and placed on a specially designed easel. Two platform lifts will make it possible to study the entire canvas, which measures 379.5 cm in height and 454.5 cm in width.

Advanced imaging techniques

Researchers will make use of high resolution photography, as well as a variety of advanced imaging techniques, such as macro X-ray fluorescence scanning (macro-XRF) and hyperspectral imaging, also called infrared reflectance imaging spectroscopy (RIS), to accurately determine the condition of the painting.

56 macro-XRF scans

The Night Watch will be scanned millimetre by millimetre using a macro X-ray fluorescence scanner (macro-XRF scanner). This instrument uses X-rays to analyse the different chemical elements in the paint, such as calcium, iron, potassium and cobalt. From the resulting distribution maps of the various chemical elements in the paint it is possible to determine which pigments were used. The macro-XRF scans can also reveal underlying changes in the composition, offering insights into Rembrandt’s painting process. To scan the entire surface of the The Night Watch it will be necesary to make 56 scans, each one of which will take 24 hours.

12,500 high-resolution photographs

A total of some 12,500 photographs will be taken at extremely high resolution, from 180 to 5 micrometres, or a thousandth of a millimetre. Never before has such a large painting been photographed at such high resolution. In this way it will be possible to see details such as pigment particles that normally would be invisible to the naked eye. The cameras and lamps will be attached to a dynamic imaging frame designed specifically for this purpose.

Glass chamber

Operation Night Watch is for everyone to follow and will take place in full view of the visiting public in an ultra-transparent glass chamber designed by the French architect Jean Michel Wilmotte.

Research team

The Rijksmuseum has extensive experience and expertise in the investigation and treatment of paintings by Rembrandt. The conservation treatment of Rembrandt’s portraits of Marten Soolmans and Oopjen Coppit was completed in 2018. The research team working on The Night Watch is made up of more than 20 Rijksmuseum scientists, conservators, curators and photographers. For this research, the Rijksmuseum is also collaborating with museums and universities in the Netherlands and abroad, including the Dutch Cultural Heritage Agency (RCE), Delft University of Technology (TU Delft), the University of Amsterdam (UvA), Amsterdam University Medical Centre (AUMC), University of Antwerp (UA) and National Gallery of Art, Washington DC.

The Night Watch

Rembrandt’s Night Watch is one of the world’s most famous works of art. The painting is the property of the City of Amsterdam, and it is the heart of Amsterdam’s Rijksmuseum, where it is admired by more than two million visitors each year. The Night Watch is the Netherland’s foremost national artistic showpiece, and a must-see for tourists.

Rembrandt’s group portrait of officers and other civic guardsmen of District 2 in Amsterdam under the command of Captain Frans Banninck Cocq and Lieutenant Willem van Ruytenburch has been known since the 18th century as simply The Night Watch. It is the artist’s most ambitious painting. One of Amsterdam’s 20 civic guard companies commissioned the painting for its headquarters, the Kloveniersdoelen, and Rembrandt completed it in 1642. It is Rembrandt’s only civic guard piece, and it is famed for the lively and daring composition that portrays the troop in active poses rather than the traditional static ones.

Donors and partners

AkzoNobel is main partner of Operation Night Watch.

Operation Night Watch is made possible by The Bennink Foundation, PACCAR Foundation, Piet van der Slikke & Sandra Swelheim, American Express Foundation, Familie De Rooij, Het AutoBinck Fonds, Segula Technologies, Dina & Kjell Johnsen, Familie D. Ermia, Familie M. van Poecke, Henry M. Holterman Fonds, Irma Theodora Fonds, Luca Fonds, Piek-den Hartog Fonds, Stichting Zabawas, Cevat Fonds, Johanna Kast-Michel Fonds, Marjorie & Jeffrey A. Rosen, Stichting Thurkowfonds and the Night Watch Fund.

With the support of the Ministry of Education, Culture and Science, the City of Amsterdam, Founder Philips and main sponsors ING, BankGiro Loterij and KPN every year more than 2 million people visit the Rijksmuseum and The Night Watch.

Details:
Rembrandt van Rijn (1606-1669)
The Night Watch, 1642
oil on canvas
Rijksmuseum, on loan from the Municipality of Amsterdam

Update as of November 22, 2019

I just clicked on the Operation Night Watch link and found a collection of resources including videos of live updates from October 2019. As noted earlier, they’re not livestreaming the restoration. The October 29, 2019 ‘live update’ features a host speaking in Dutch (with English subtitles in the version I was viewing) and interviews with the scientists conducting the research necessary before they start actually restoring the painting.

Masterpieces seen in a new light

Caption: This image shows: After Raphael 1483 - 1520 probably before 1600 Oil on wood 87 x 61.3 cm Wynn Ellis Bequest, 1876 Credit: © National Gallery, London

Caption: This image shows: After Raphael 1483 – 1520
probably before 1600
Oil on wood
87 x 61.3 cm
Wynn Ellis Bequest, 1876
Credit: © National Gallery, London

An April 13, 2015 Optical Society news release (also on EurekAlert) describes a new technique for ‘seeing’ below the surface of a painting without taking samples,

A painting hanging on the wall in an art gallery tells one story. What lies beneath its surface may tell quite another.

Often in a Rembrandt, a Vermeer, a Leonardo, a Van Eyck, or any other great masterpiece of western art, the layers of paint are covered with varnish, sometimes several coats applied at different times over their history. The varnish was originally applied to protect the paint underneath and make the colors appear more vivid, but over the centuries it can degrade. Conservators carefully clean off the old varnish and replace it with new, but to do this safely it is useful to understand the materials and structure of the painting beneath the surface. Conservation scientists can glean this information by analyzing the hidden layers of paint and varnish.

Now, researchers from Nottingham Trent University’s School of Science and Technology have partnered with the National Gallery in London to develop an instrument capable of non-invasively capturing subsurface details from artwork at a high resolution. Their setup, published in an Optics Express paper, will allow conservators and conservation scientists to more effectively peek beneath the surface of paintings and artifacts to learn not only how the artist built up the original composition, but also what coatings have been applied to it over the years.

Traditionally, analyzing the layers of a painting requires taking a very small physical sample — usually around a quarter of a millimeter across — to view under a microscope. The technique provides a cross-section of the painting’s layers, which can be imaged at high resolution and analyzed to gain detailed information on the chemical composition of the paint, but does involve removing some original paint, even if only a very tiny amount. When studying valuable masterpieces, conservation scientists must therefore sample very selectively from already-damaged areas, often only taking a few minute samples from a large canvas.

More recently, researchers have begun to use non-invasive imaging techniques to study paintings and other historical artifacts. For example, Optical Coherence Tomography (OCT) was originally developed for medical imaging but has also been applied to art conservation. Because it uses a beam of light to scan the intact painting without removing physical samples, OCT allows researchers to analyze the painting more extensively. However, the spatial resolution of commercially-available OCT setups is not high enough to fully map the fine layers of paint and varnish.

The Nottingham Trent University researchers gave OCT an upgrade. “We’re trying to see how far we can go with non-invasive techniques. We wanted to reach the kind of resolution that conventional destructive techniques have reached,” explained Haida Liang, who led the project.

In OCT, a beam of light is split: half is directed towards the sample, and the other half is sent to a reference mirror. The light scatters off both of these surfaces. By measuring the combined signal, which effectively compares the returned light from the sample versus the reference, the apparatus can determine how far into the sample the light penetrated. By repeating this procedure many times across an area, researchers can build up a cross-sectional map of the painting.

Liang and her colleagues used a broadband laser-like light source — a concentrated beam of light containing a wide range of frequencies. The wider frequency range allows for more precise data collection, but such light sources were not commercially available until recently.

Along with a few other modifications, the addition of the broadband light source enabled the apparatus to scan the painting at a higher resolution. When tested on a late 16th-century copy of a Raphael painting, housed at the National Gallery in London, it performed as well as traditional invasive imaging techniques.

“We are able to not only match the resolution but also to see some of the layer structures with better contrast. That’s because OCT is particularly sensitive to changes in refractive index,” said Liang. In some places, the ultra-high resolution OCT setup identified varnish layers that were almost indistinguishable from each other under the microscope.

Eventually, the researchers plan to make their instrument available to other art institutions. It could also be useful for analyzing historical manuscripts, which cannot be physically sampled in the same way that paintings can.

In a parallel paper recently published in Optics Express, the researchers also improved the depth into the painting that their apparatus can scan. The two goals are somewhat at odds: using a longer wavelength light source could enhance the penetration depth, but shorter wavelength light (as used in their current setup) provides the best resolution.

“The next challenge is perhaps to be able to do that in one instrument, as well as to extract chemical information from different layers,” said Liang.

Here are links to and citations for the two recent papers published by Liang and her team,

Ultra-high resolution Fourier domain optical coherence tomography for old master paintings by C. S. Cheung, M. Spring, and H. Liang. Optics Express, Vol. 23, Issue 8, pp. 10145-10157 (2015) http://dx.doi.org/10.1364/OE.23.010145

High resolution Fourier domain optical coherence tomography in the 2 μm wavelength range using a broadband supercontinuum source by C. S. Cheung, J. M. O. Daniel, M. Tokurakawa, W. A. Clarkson, and H. Liang. Optics Express, Vol. 23, Issue 3, pp. 1992-2001 (2015) http://dx.doi.org/10.1364/OE.23.001992

Both papers are open access.

Lawren Harris (Group of Seven), art authentication, and the Canadian Conservation Institute* (addendum to four-part series)

I recently wrote an exhaustive four-part series (links at the end of this posting) featuring Raman spectroscopy testing of an authenticated (Hurdy Gurdy) and a purported (Autumn Harbour) Lawren Harris paintings. During the course of my research, I sent a query to the Canadian Conservation Institute to disprove or confirm my statements regarding Canada and its database of art pigments,

.. According to some informal sources, Canada has a very small (almost nonexistent) data bank of information about pigments used in its important paintings. For example, the federal government’s Canadian Conservation Institute has a very small database of pigments and nothing from Lawren Harris paintings [unconfirmed at time of publication; June 18, 2014 query outstanding] …

Marie-Claude Corbeil, Ph.D. Gestionnaire de la Division de la science de la conservation | Manager of Conservation Science Division, very kindly replied to my query with this on July 10, 2014 (I believe she was on holidays [en vacances] when my query was received in June),

The Canadian Conservation Institute (CCI) has been conducting research into the materials and techniques of Canadian artists (mainly 20th-century artists) since the early 1990s. Databases were created for each artists. At the moment CCI has no such database on Harris.

The CCI is the only institution in Canada carrying out this kind of research. I would add that European conservation institutes or laboratories have a long tradition of conducting this type of research focusing mainly on European art, basically because many were created long before North-American conservation institutes or laboratories were established.

… An important point to make is that scientific investigation is only one part of an authentication study. Authentication should start with stylistic study and research into the provenance of the artwork which are carried out by curators and art historians.

Regarding your question about Raman spectroscopy, I would say that Raman spectroscopy is only one of many techniques that can be used to analyse paint or any other material. At CCI we often use up to six techniques to analyse paint to obtain the full makeup of the sample including pigments, fillers and binding media. I should also add that analysis of material is carried out at CCI to answer questions related to a number of issues, including but not limited to authentication. Analysis is often carried out to understand the degradation of museum objects and works of art, or to provide information required during the course of a conservation treatment.

Thank you for this excellent explanation and for your time.

Art (Lawren Harris and the Group of Seven), science (Raman spectroscopic examinations), and other collisions at the 2014 Canadian Chemistry Conference

Part 1

Part 2

Part 3

Part 4

ETA July 14, 2014 at 1305 PDT: For those who want more information, Ms. Corbeil has provided some articles about the CCI and its Canadian Artists Painting Materials Research Project:

The Canadian Artists’ Painting Materials Project, 1992, J. M. Taylor. (PDF)

CCI 1992 Taylor

Detecting Art Fraud: Sometimes Scientific Examination Can Help, 1993. J. M. Taylor (PDF)

CCI 1993 Taylor
The Canadian Artists Painting Materials Research Project, 1995, Marie-Claude Corbeil (PDF)

CCI 1995 Corbeil

*’Istitute’ changed to ‘Institute’ on Jan. 14, 2016.

Italians and Polish collaborate on nanoscale study of vanishing Da Vinci self-portrait

In addition to a new nondamaging technique to examine paintings (my June 2, 2014 post: Damage-free art authentication and spatially offset Raman spectroscopy [SORS]), there’s a new report in a June 3, 2014 news item on ScienceDaily about a nondamaging technique to examine paper such as the paper on which holds a Da Vinci self-portrait,

One of Leonardo da Vinci’s masterpieces, drawn in red chalk on paper during the early 1500s and widely believed to be a self-portrait, is in extremely poor condition. Centuries of exposure to humid storage conditions or a closed environment has led to widespread and localized yellowing and browning of the paper, which is reducing the contrast between the colors of chalk and paper and substantially diminishing the visibility of the drawing.

A group of researchers from Italy and Poland with expertise in paper degradation mechanisms was tasked with determining whether the degradation process has now slowed with appropriate conservation conditions — or if the aging process is continuing at an unacceptable rate.

Caption: This is Leonardo da Vinci's self-portrait as acquired during diagnostic studies carried out at the Central Institute for the Restoration of Archival and Library Heritage in Rome, Italy. Credit: M. C. Misiti/Central Institute for the Restoration of Archival and Library Heritage, Rome

Caption: This is Leonardo da Vinci’s self-portrait as acquired during diagnostic studies carried out at the Central Institute for the Restoration of Archival and Library Heritage in Rome, Italy.
Credit: M. C. Misiti/Central Institute for the Restoration of Archival and Library Heritage, Rome

The June 3, 2014 American Institute of Physics news release on EurekAlert provides more detail about the work,

… the team developed an approach to nondestructively identify and quantify the concentration of light-absorbing molecules known as chromophores in ancient paper, the culprit behind the “yellowing” of the cellulose within ancient documents and works of art.

“During the centuries, the combined actions of light, heat, moisture, metallic and acidic impurities, and pollutant gases modify the white color of ancient paper’s main component: cellulose,” explained Joanna Łojewska, a professor in the Department of Chemistry at Jagiellonian University in Krakow, Poland. “This phenomenon is known as ‘yellowing,’ which causes severe damage and negatively affects the aesthetic enjoyment of ancient art works on paper.”

Chromophores are the key to understanding the visual degradation process because they are among the chemical products developed by oxidation during aging and are, ultimately, behind the “yellowing” within cellulose. Yellowing occurs when “chromophores within cellulose absorb the violet and blue range of visible light and largely scatter the yellow and red portions — resulting in the characteristic yellow-brown hue,” said Olivia Pulci, a professor in the Physics Department at the University of Rome Tor Vergata.

To determine the degradation rate of Leonardo’s self-portrait, the team created a nondestructive approach that centers on identifying and quantifying the concentration of chromophores within paper. It involves using a reflectance spectroscopy setup to obtain optical reflectance spectra of paper samples in the near-infrared, visible, and near-ultraviolet wavelength ranges.

Once reflectance data is gathered, the optical absorption spectrum of cellulose fibers that form the sheet of paper can be calculated using special spectroscopic data analysis.

Then, computational simulations based on quantum mechanics — in particular, Time-Dependent Density Functional Theory, which plays a key role in studying optical properties in theoretical condensed matter physics — are tapped to calculate the optical absorption spectrum of chromophores in cellulose.

“Using our approach, we were able to evaluate the state of degradation of Leonardo da Vinci’s self-portrait and other paper specimens from ancient books dating from the 15th century,” said Adriano Mosca Conte, a researcher at the University of Rome Tor Vergata. “By comparing the results of ancient papers with those of artificially aged samples, we gained significant insights into the environmental conditions in which Leonardo da Vinci’s self-portrait was stored during its lifetime.”

Their work revealed that the type of chromophores present in Leonardo’s self portrait are “similar to those found in ancient and modern paper samples aged in extremely humid conditions or within a closed environment, which agrees with its documented history,” said Mauro Missori, a researcher at the Institute for Complex Systems, CNR, in Rome, Italy.

One of the most significant implications of their work is that the state of degradation of ancient paper can be measured and quantified by evaluation of the concentrations of chromophores in cellulose fibers. “The periodic repetition of our approach is fundamental to establishing the formation rate of chromophores within the self-portrait. Now our approach can serve as a precious tool to preserve and save not only this invaluable work of art, but others as well,” Conte noted.

Absolutely fascinating stuff to those of use who care about yellowing paper. (Having worked in an archives, I care deeply.) Here’s a link to and a citation for the study,

Visual degradation in Leonardo da Vinci’s iconic self-portrait: A nanoscale study by A. Mosca Conte, O. Pulci, M. C. Misiti, J. Lojewska, L. Teodonio1, C. Violante, and M. Missori. Appl. Phys. Lett. 104, 224101 (2014); http://dx.doi.org/10.1063/1.4879838

This is an open access study.

Bacterial art lovers

With all the emphasis on eradicating bacteria (with signs everywhere telling you to wash your hands, often will illustrated instructions), it’s easy to forget that some bacteria are necessary for health. It also turns out that some bacteria can help us preserve art works. From the June 7, 2011 news item on Nanowerk,

Researchers at the Institute of Heritage Restoration (IRP) and the Centre for Advanced Food Microbiology (CAMA), both from the Polytechnic University of Valencia (Spain), are beginning to experiment with this new technique on the frescoes of Antonio Palomino from the 17th century in the Church of Santos Juanes in Valencia.

They have shown that a certain type of micro-organism is capable of cleaning works of art in a fast, specific and respectful way as well as being non-toxic for the restorer or the environment.

Here’s the background on the problem the art restorers were trying to fix (from the news item),

The project came about when the IRP [Institute of Heritage Restoration] was in the process of restoring the murals of the Church of Santos Juanes that were virtually destroyed after a fire in 1936 and were improperly restored in the 1960s. The researchers tested new techniques for filling with transferred printed digital images in spaces without painting, but had great difficulty dealing with salt efflorescence, the white scabs caused by the build up of crystallized salts and the enormous amount of gelatine glue remaining on the pulled-off murals.

With the problem defined, the researchers then investigated a technique developed in Italy that looked promising (from the news item),

Therefore, Rosa María Montes and Pilar Bosch travelled to Italy to learn from the authors about the pioneering studies that used bacteria to remove hardened glue that was very difficult to treat with conventional methods.

The restoration of the Campo Santo di Pisa wall paintings was performed under the direction of Gianluiggi Colalucci, restorer of the Sistine Chapel, and his colleagues Donatella Zari and Carlo Giantomassi who applied the technique developed by microbiologist Giancarlo Ranalli. The researcher had also been testing with black crusts that appear on sculptures and artistic monuments.

The team returned to Spain to practice the technique and add some refinements (from the news item),

Back in Valencia, the multidisciplinary team perfected this method and trained the most suitable strain of Pseudomonas bacteria to literally eat the saline efflorescence found in the lunettes of the vault behind which pigeons nest.

“By the action of gravity and evaporation, the salts of organic matter in decomposition migrate to the paintings and produce a white crust hiding the work of art and sometimes can also cause the loose of the painting layer” says Pilar Bosch.

These scientists have managed to reduce the application time, and have also innovated in the way of extending the bacteria. According to Dr. Bosch: “In Italy they use cotton wool to apply the micro-organisms. We, however, have developed a gel that acts on the surface, which prevents moisture from penetrating deep into the material and causing new problems.

“After an hour and a half, we remove the gel with the bacteria. The surface is then cleaned and dried.” Without a wet environment, the remaining bacteria die.

Here’s a picture that demonstrates the advantages of the new process according to whomever wrote up the caption in Spanish (I may have gotten the translation wrong),

Las ventajas del nuevo proceso (The advantages of the new process) image downloaded from RUVID website

If you do have the Spanish language skills you can read the article as it was written originally here.

I have from time to time (in my Sept. 20, 2010 posting and Oct. 26, 2009 posting) featured a different nano art restoration technique as it’s practiced by Piero Baglioni’s (Correction Mar. 1, 2013: Name was changed from Pier Baglioni) team on projects in Mexico and Italy. Baglioni and his cohorts use a technique involving a micro-emulsion partially derived from cellulose. From an Oct. 26, 2009 article written by Michael Berger on Nanowerk,

The solution developed by Baglioni and his team has been to develop a micro-emulsion cleaning agent that is designed to dissolve only the organic molecules on the surface of a painting or other artwork. This emulsion is not only suitable for removing the aged coating on paintings but also for the removal of aged organic varnishes from the surface of easel paintings or gilded surfaces, as an alternative to gels traditionally used in conservation.

The cleaning agent is made by dissolving the volatile solvent p-xylene in water and thickening it into a gel with hydrophobically modified hydroxyethylcellulose (hmHEC) – a gelling and thickening agent derived from cellulose. This oil-in-water emulsion has a microstructure of tiny droplets of oil-coated water trapped in the cellulose chains, and these will dissolve organic polymers on the painting’s surface, thereby restoring the original, clean finish.

Painting whisperers: McGill University scientists develop photoacoustic technique for art restoration

Listening to a paint pigment to determine its composition is a new technique for art restoration that scientists at McGill University (Montréal, Canada) have developed. From the news release,

A team of McGill chemists have discovered that a technique known as photoacoustic infrared spectroscopy could be used to identify the composition of pigments used in art work that is decades or even centuries old. Pigments give artist’s materials colour, and they emit sounds when light is shone on them.

“The chemical composition of pigments is important to know, because it enables museums and restorers to know how the paints will react to sunlight and temperature changes,” explained Dr. Ian Butler, lead researcher and professor at McGill’s Department of Chemistry. Without a full understanding of the chemicals involved in artworks, preservation attempts can sometimes lead to more damage than would occur by just simply leaving the works untreated.

Photoacoustic infrared spectroscopy is based on Alexander Graham Bell’s 1880 discovery that showed solids could emit sounds when exposed to sunlight, infrared radiation or ultraviolet radiation. Advances in mathematics and computers have enabled chemists to apply the phenomenon to various materials, but the Butler’s team is the first to use it to analyze typical inorganic pigments that most artists use.

The researchers have classified 12 historically prominent pigments by the infrared spectra they exhibit – i.e., the range of noises they produce – and they hope the technique will be used to establish a pigment database. “Once such a database has been established, the technique may become routine in the arsenal of art forensic laboratories,” Butler said. The next steps will be to identify partners interested in developing standard practices that would enable this technique to be used with artwork.

Strictly speaking this is not usually in my bailiwick but art restoration does interest me and there’s been a fair amount of interest in using nanotechnology-enabled techniques to minimize the damage that art restoration paradoxically imposes as conservators try to save the art work. There is a blog for the restoration of Van Gogh’s The Bedroom (no nano-enabled techniques) which is taking place at the Van Gogh Museum (first mentioned here in my March 16, 2010 posting).

Science policy, innovation and more on the Canadian 2010 federal budget; free access in the true north; no nano for Van Gogh’s The Bedroom; frogs, foam and biofuels

There are more comments about Canada’s 2010 federal budget on the Canadian Science Policy Centre website along with listings of relevant news articles which they update regularly. There’s also a federal budget topic in the forums section but it doesn’t seem have attracted much commentary yet.

The folks at The Black Hole blog offer some pointed commentary with regard to the budget’s treatment of post doctorate graduates. If I understand the comments correctly, the budget has clarified the matter of taxation, i. e., post doctoral grants are taxable income, which means that people who were getting a break on taxes are now losing part of their income. The government has also created a new class of $70,000 post doctoral grants but this will account for only 140 fellowships. With some 6000 post doctoral fellows this means only 2% of the current pool of applicants will receive these awards. Do read The Black Hole post as they clarify what this means in very practical terms.

There’s been another discussion outcome from the 2010 budget, a renewed interest in innovation. I’m kicking off my ‘innovation curation efforts’ with this from an editorial piece by Carol Goar in the Toronto Star,

Five Canadian finance ministers have tried to crack the productivity puzzle. All failed. Now Jim Flaherty is taking a stab at it.

Here is the conundrum: We don’t use our brainpower to create new wealth. We have a highly educated population, generous tax incentives for research and development and lower corporate tax rates than any leading economic power. Yet our businesses remain reluctant to invest in new products and technologies (with a few honourable exceptions such as Research in Motion, Bombardier and Magna). They don’t even capitalize on the exciting discoveries made in our universities and government laboratories.

Economists are starting to ask what’s wrong. Canada ranked 14th in business spending on research and development – behind all the world’s leading industrial powers and even smaller nations such as Belgium and Ireland – in the latest statistical roundup by the Organization for Economic Cooperation and Development.

I believe she’s referring to the 2009 OECD scorecard in that last bit (you can find the Canada highlights here).

There are many parts to this puzzle about why Canadians and their companies are not innovative.  Getting back to Goar’s piece,

Kevin Lynch, who served as Stephen Harper’s top adviser from 2006 to 2009 [and is now the vice-chair of the Bank of Montreal Financial Group], has just written an article in Policy Options, an influential magazine, laying the blame squarely on corporate Canada. He argues that, unless business leaders do their part, it makes little sense to go on spending billions of dollars on research and development. “In an era of fiscal constraint, there has to be a compelling narrative to justify new public investments when other areas are being constrained,” he says.

Here’s a possible puzzle piece, in yesterday’s (March 15, 2010) posting I noted a study by academic, Mary J. Benner, where she pointed out that securities analysts do not reward/encourage established US companies such as Polaroid (now defunct) and Kodak to adopt new technologies. I would imagine that the same situation exists here in Canada.

For another puzzle piece: I’ve made mention of the mentality that a lot of entrepreneurs (especially in Canadian high tech) have and see confirmation  in a Globe and Mail article by Simon Avery about the continuing impact of the 2000 dot com meltdown where he investigates some of the issues with venture capital and investment as well as this,

“It’s a little bit about getting into the culture of winning, like the Olympics we just had,” says Ungad Chadda, senior vice-president of the Toronto Stock Exchange. “I don’t think the technology entrepreneurs around here are encouraged and supported to think beyond the $250-million cheque that a U.S. company can give them.”

One last comment from  Kevin Lynch (mentioned in the second of the Goar excerpts) about innovation and Canada from his recent opinion piece in the Globe and Mail,

A broader public dialogue is essential. We need to make the question “What would it take for Canada to be an innovative economy for the 21st century?” part of our public narrative – partly because our innovation deficit is a threat to our competitiveness and living standards, and partly because we can be a world leader in innovation. We should aspire to be a nation of innovators. We should rebrand Canada as technologically savvy, entrepreneurial and creative.

Yes, Mr. Lynch a broader dialogue would be delightful but there does seem to be an extraordinary indifference to the notion from many quarters. Do I seem jaundiced? Well, maybe that’s because I’ve been trying to get some interest in having a Canadian science policy debate and not getting very far with it. In principle, people call for more dialogue but that requires some effort to organize and a willingness to actually participate.

(As for “rebranding”, is anyone else tired of hearing that word or its cousin branding?)

On a completely other note, the University of Ottawa has announced that it is supporting open access to its faculty’s papers with institutional funding. From the news release,

According to Leslie Weir, U of Ottawa’s chief librarian, the program encompasses several elements, including a new Open Access (or OA) repository for peer-reviewed papers and other “learning objects”; an “author fund” for U of Ottawa researchers to help them cover open-access fees charged by journal publishers; a $50,000-a-year budget to digitize course materials and make them available to anyone through the repository; and support for the University of Ottawa Press’s OA journals.

But the university stopped short of requiring faculty members to deposit their papers with the new repository. “We all agreed that incentives and encouragement was the best way to go,” said Ms. Weir, who worked on the program with an internal group of backers, including Michael Geist, professor of intellectual property law, and Claire Kendall, a professor in the faculty of medicine who has been active in OA medical journals.

There is some criticism of the decision to make the programme voluntary. Having noticed the lack of success that voluntary reporting of nanomaterials has had, I’m inclined to agree with the critics. (Thanks to Pasco Phronesis for pointing me to the item.)

If you’ve ever been interested in art restoration (how do they clean and return the colours of an old painting to its original hues?, then the Van Gogh blog is for you. A member of the restoration team is blogging each step of The Bedroom’s (a famous Van Gogh painting) restoration. I was a little surprised that they don’t seem to be using any of the new nano-enabled techniques for examining the painting or doing the restoration work.

Given the name for this website, I have to mention the work done with frogs in pursuit of developing new biofuels by scientists at the University of Cincinnati. From the news item on Nanotechnology Now,

In natural photosynthesis, plants take in solar energy and carbon dioxide and then convert it to oxygen and sugars. The oxygen is released to the air and the sugars are dispersed throughout the plant — like that sweet corn we look for in the summer. Unfortunately, the allocation of light energy into products we use is not as efficient as we would like. Now engineering researchers at the University of Cincinnati are doing something about that.

The researchers are finding ways to take energy from the sun and carbon from the air to create new forms of biofuels, thanks to a semi-tropical frog species [Tungara frog].

Their work focused on making a new artificial photosynthetic material which uses plant, bacterial, frog and fungal enzymes, trapped within a foam housing, to produce sugars from sunlight and carbon dioxide.

Here’s an illustration of the frog by Megan Gundrum, 5th year DAAP student (I tried find out what DAAP stands for but was unsuccessful, ETA: Mar.31.10, it is the Design, art, and architecture program at the University of Cincinnati),

illustration by Megan Gundrum, 5th year DAAP student

Thank you to the University of Cincinnati for making the image available.