Tag Archives: art authentication

Terahertz imagers at your fingertips

It seems to me that I stumbled across quite a few carbon nanotube (CNT) stories in 2018. This one comes courtesy of Japan (from a June 28, 2018 news item on Nanowerk),

Researchers at Tokyo Tech have developed flexible terahertz imagers based on chemically “tunable” carbon nanotube materials. The findings expand the scope of terahertz applications to include wrap-around, wearable technologies as well as large-area photonic devices.

Here’s a peek at an imager,

Figure 1. The CNT-based flexible THz imager (a) Resting on a fingertip, the CNT THz imager can easily wrap around curved surfaces. (b) Just by inserting and rotating a flexible THz imager attached to the fingertip, damage to a pipe was clearly detected. Courtesy Tokyo Tech

A June 28, 2018 Tokyo Tech Institute press release (also on Eurekalert), which originated the news item, provides more detail,

Carbon nanotubes (CNTs) are beginning to take the electronics world by storm, and now their use in terahertz (THz) technologies has taken a big step forward.

Due to their excellent conductivity and unique physical properties, CNTs are an attractive option for next-generation electronic devices. One of the most promising developments is their application in THz devices. Increasingly, THz imagers are emerging as a safe and viable alternative to conventional imaging systems across a wide range of applications, from airport security, food inspection and art authentication to medical and environmental sensing technologies.

The demand for THz detectors that can deliver real-time imaging for a broad range of industrial applications has spurred research into low-cost, flexible THz imaging systems. Yukio Kawano of the Laboratory for Future Interdisciplinary Research of Science and Technology, Tokyo Tech, is a world-renowned expert in this field. In 2016, for example, he announced the development of wearable terahertz technologies based on multiarrayed carbon nanotubes.

Kawano and his team have since been investigating THz detection performance for various types of CNT materials, in recognition of the fact that there is plenty of room for improvement to meet the needs of industrial-scale applications.

Now, they report the development of flexible THz imagers for CNT films that can be fine-tuned to maximize THz detector performance.

Publishing their findings in ACS Applied Nano Materials, the new THz imagers are based on chemically adjustable semiconducting CNT films.

By making use of a technology known as ionic liquid gating1, the researchers demonstrated that they could obtain a high degree of control over key factors related to THz detector performance for a CNT film with a thickness of 30 micrometers. This level of thickness was important to ensure that the imagers would maintain their free-standing shape and flexibility, as shown in Figure 1 [see above].

“Additionally,” the team says, “we developed gate-free Fermi-level2 tuning based on variable-concentration dopant solutions and fabricated a Fermi-level-tuned p-n junction3 CNT THz imager.” In experiments using this new type of imager, the researchers achieved successful visualization of a metal paper clip inside a standard envelope (see Figure 2.)

Non-contact, non-destructive visualization

Figure 2. Non-contact, non-destructive visualization

The CNT THz imager enabled clear, non-destructive visualization of a metal paper clip inside an envelope.

The bendability of the new THz imager and the possibility of even further fine-tuning will expand the range of CNT-based devices that could be developed in the near future.

Moreover, low-cost fabrication methods such as inkjet coating could make large-area THz imaging devices more readily available.

1 Ionic liquid gating

A technique used to modulate a material’s charge carrier properties.

2 Fermi level

A measure of the electrochemical potential for electrons, which is important for determining the electrical and thermal properties of solids. The term is named after the Italian–American physicist Enrico Fermi.

3 p-n junction

Refers to the interface between positive (p-type) and negative (n-type) semiconducting materials. These junctions form the basis of semiconductor electronic devices.

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

Fermi-Level-Controlled Semiconducting-Separated Carbon Nanotube Films for Flexible Terahertz Imagers by Daichi Suzuki, Yuki Ochiai, Yota Nakagawa, Yuki Kuwahara, Takeshi Saito, and Yukio Kawano. ACS Appl. Nano Mater., 2018, 1 (6), pp 2469–2475 DOI: 10.1021/acsanm.8b00421 Publication Date (Web): June 6, 2018

Copyright © 2018 American Chemical Society

This paper is behind a paywall.

NANOART Research Tool offers affordable paint analysis

There’s some encouraging news for art conservators and authenticators, an affordable nanotech-based kit for greater accuracy analyzing ancient (or old)  paint is one step closer according to a Jan. 11, 2016 notice on CORDIS,

Developed through the EU-funded NANOART project, the new testing kit has already been applied to identify binders such as collagen and ovalbumin in ancient paint, not only in model samples painted in the lab but also in real samples collected from works of art.

‘Once fully completed, our new tool will be made available to conservation scientists from around the world at an affordable cost (an assay can cost around EUR 0.5 per target), which will facilitate greater knowledge about historical works of art and help international museums, restoration art studios and laboratories to plan the best conservation and preventive strategies,’ explains NANOART project coordinator Dr Jesus de la Fuente from the CSIC/University of Zaragoza, Spain.

In addition, the sensitiveness of the project’s new nanotechnology-based methods means that smaller samples are required to be taken from the artwork for analysis. This in itself will help to better preserve our cultural heritage.

In order to characterise ancient paints, experts have often relied on conventional molecular biology methodologies that were developed decades ago. The concept behind the NANOART project was that these techniques could be substituted by more sensitive, inexpensive and faster techniques that take advantage of emerging nanotechnologies.

Furthermore, conventional methods – apart from being expensive – are also only available at a few laboratories, and require specialised personnel and equipment. A key objective of the NANOART project has been to address the cost issue by applying techniques developed for clinical diagnosis. In this way, the project is also highly original as it aims to take latest developments in clinical medicine and apply them to the conservation and preservation of cultural heritage.

‘The innovative nature of the project is also denoted by the fact that there is currently no method or kit available that can be easily used at point-of-care to analyse paints without requiring expensive equipment and extensive training,’ says Ana Claro, research fellow from the INA/University of Zaragoza. ‘With the NANOART kit, the final user will be able to conduct an affordable analysis (in some cases at the cost of only a few euros) by simply following the instructions. Within a four-hour period, the results will be available.’

The potential opportunities opened up by the new analytical nanotechnology are huge. For example, developed in parallel with the NANOART kit, a spin-off company called NanoImmunotech has been launched in order to develop devices to detect bacterial infection in meat using the same technology as used in NANOART.

‘This opens our technology to other applications far from cultural heritage applications,’ says de la Fuente. ‘However, we would like to continue further developing novel uses of NANOART technology for other applications in cultural heritage, and our next step will be to look for funding to develop an even more user friendly device.’

This announcement comes just as the NANOART project is scheduled to be completed (Jan. 31, 2016) according to its webpage on CORDIS.

For those with Spanish language skills, there’s this Jan. 11, 2016 news item on the Catalunya Vanguardista website (I believe the English language version above is a machine translation with this being the original text),

Nanotecnología para analizar pinturas históricas de forma barata y precisa

Empleando nanotecnologías, se ha creado un equipo de diagnóstico clínico destinado a analizar capas de pintura antiguas que podría ahorrar costes a los profesionales de la conservación y permitirles alcanzar mayor precisión.

Cordis / El nuevo equipo de ensayo, desarrollado mediante el proyecto financiado con fondos europeos NANOART, ya se ha empleado en la identificación de aglutinantes como el colágeno y la ovoalbúmina en pinturas históricas. Además, los resultados se han obtenido tanto con muestras pintadas en el laboratorio como con otras extraídas de obras de arte.

«Una vez completemos su desarrollo, nuestra herramienta quedará a disposición de científicos de todo el mundo dedicados a la conservación por un módico precio (cada ensayo costará cerca de medio euro por objetivo). De este modo se obtendrá un conocimiento más profundo sobre las obras de arte históricas y tanto museos como talleres de restauración y laboratorios podrán plantear las estrategias de conservación y prevención idóneas», explicó el coordinador del proyecto, el Dr. Jesús de la Fuente del Instituto de Ciencia de los Materiales —centro mixto dependiente del CSIC y la Universidad de Zaragoza (España)—.Además, la sensibilidad ofrecida por los métodos nanotecnológicos propuestos por el proyecto permite extraer muestras de menor tamaño de las obras de arte, lo cual contribuirá a conservar mejor el patrimonio cultural.Para caracterizar pinturas antiguas, hasta ahora los expertos solían emplear metodologías convencionales de la biología molecular desarrolladas hace decenios. La propuesta del proyecto NANOART pasa por sustituir estas técnicas por otras más sensibles, baratas y rápidas que se valen de las nanotecnologías emergentes.

Es más, los métodos convencionales, además de resultar caros, sólo están a disposición de unos pocos laboratorios que cuentan con equipos y personal especializados. NANOART se propuso sobre todo abaratar los costes mediante el empleo de técnicas de diagnóstico del ámbito clínico. La originalidad de este planteamiento es notoria, pues aprovecha los últimos progresos logrados en medicina clínica para aplicarlos a la conservación y la protección del patrimonio cultural.

«La naturaleza innovadora del proyecto también obedece a la carencia hoy en día de un método o equipo que pueda emplearse con facilidad in situ para analizar pinturas sin necesidad de equipos caros ni formación exhaustiva», afirmó Ana Claro, investigadora del INA de la Universidad de Zaragoza. «Gracias al equipo de NANOART, el usuario final podrá ejecutar ensayos asequibles, en algunos casos por valor de tan sólo unos pocos euros, siguiendo las instrucciones proporcionadas. Los resultados estarán disponibles en cuatro horas».

Las oportunidades que ofrece la nueva nanotecnología analítica son enormes. Por ejemplo, la empresa derivada NanoImmunotech se ha puesto en marcha en paralelo al desarrollo del equipo de NANOART para que cree servicios con los que detectar infecciones bacterianas en la carne mediante los mismos métodos empleados por el proyecto en el ámbito del arte.

«De esta forma se amplían las aplicaciones de la tecnología a otros campos muy alejados del patrimonio cultural», afirmó de la Fuente. «No obstante, seguiremos indagando en nuevos usos de la tecnología de NANOART relacionados con el patrimonio cultural y procederemos ya a buscar fuentes de financiación que nos permitan crear un dispositivo aún más fácil de usar».

I expect the folks at the Canadian Conservation Institute (CCI) and other such insitutions are keeping a close eye on developments of this nature. The institute was mentioned here in the context of a series I wrote on attempts to authenticate a painting, Autumn Harbour, as a Lawren Harris (one of Canada’s Group of Seven painters). My July 14, 2014 post was devoted to a response from Marie-Claude Corbeil to a query about scientific investigation of visual art,

… [the response],

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.

I was quite fascinated by the whole thing and wrote a four-part series about Autumn Harbour, Lawren Harris, and much more, as well as, the July 14, 2014 post, which has links to the Autumn Harbour series along with the response from the CCI and links to articles recommended by Corbeil.

Authenticating ancient Mesoamerican artifacts with nanoSEM

A Nov. 12, 2014 news item on Azonano describes an upcoming Nov. 14, 2014 presentation from researchers at the Smithsonian Institute about authenticating artifacts at the 61st annual AVS symposium being held in Maryland (US) from Nov. 9 – 14 , 2014,

Geologist Timothy Rose of the Smithsonian Institution’s Analytical Laboratories is accustomed to putting his lab’s high-tech nanoscale scanning electron microscope (nanoSEM) to work evaluating the mineral composition of rocks and meteorites. Lately, though, the nanoSEM has been enlisted for a different kind of task: determining the authenticity of ancient Mesoamerican artifacts.

In ongoing studies, Rose and his colleague Jane Walsh have now analyzed hundreds of artifacts, including carved stone figurines and masks and ceramic pieces from the ancient Olmec, Maya, Teotihuacan and Mezcala civilizations dating from 1500 B.C. to A.D. 600. “With our modern imaging and analytical tools we can look at objects at very high magnification, which can reveal new details about how, and sometimes when, objects were created,” he said.

A Nov. 12, 2014 AVS news release, which originated the news item, describes the work in more detail,

The nanoSEM used by Rose and his colleagues has the ability to function over a range of pressures. “Being able to work in the low-vacuum mode allows us to put samples into the microscope au naturel without coating them with an electrically conductive material such as carbon, which would be almost impossible to remove from a specimen,” he said.

In one study, Rose and colleagues used the nanoSEM to study stone masks from Teotihuacan, a pre-Columbian site located 30 miles northwest of Mexico City. The masks, about the size of a human face, were too big to be put into the device (and, more importantly, could not be removed from their respective museums or drilled or otherwise altered to obtain samples for analysis). However, silicone molds that were made of the objects to study tool marks with an optical microscope did remove tiny mineral grains from deep within cracks and drill holes. Chemical evaluation of these grains using the nanoSEM’s X-ray spectrographic analysis system showed that some were diatoms—common single-celled algae with cell walls made of silica. Diatomaceous earth is “a very fine powdery siliceous rock comprised entirely of diatoms that would make very nice polish for the stone of these specific masks,” Rose said. “We believe we found abrasive grains and polish that was used in the manufacturing process.”

In a separate study of artifacts confiscated by the federal government, the researchers found some pieces to be partially coated with a layer of what looked to be modern gypsum plaster. In other words, the pieces were fakes. However, Rose noted, a surprisingly small percentage of the objects evaluated to date have shown modern tools marks or other evidence of recent origins. One unique ceramic handled pot analyzed in detail, for example, had five chemically distinct layers that appeared to be original Olmec fresco paint—a level of craftsmanship that, he said, is unlikely to have been the work of modern artisans.

Presentation #CS-FrM3, “Faces from the Past: Microbeam Imaging and Analysis of Artifacts from Ancient Mesoamerica,” is at 9:00 a.m. Eastern Time on Friday, Nov. 14, 2014.

AVS provides a symposium introduction page explaining the purpose of these meetings,

The AVS International Symposium and Exhibition addresses cutting-edge issues associated with materials, processing, and interfaces in both the research and manufacturing communities. The weeklong Symposium fosters a multidisciplinary environment that cuts across traditional boundaries between disciplines, featuring papers from AVS technical divisions, technology groups, and focus topics on emerging technologies. The equipment exhibition is one of the largest in the world and provides an excellent opportunity to view the latest products and services offered by over 200 participating companies. More than 2,000 scientists and engineers gather from around the world to attend.

At one time, AVS stood for American Vacuum Society but over time things change and while I imagine they didn’t want to lose their branding as AVS, they also didn’t want to constrain themselves with the word ‘vacuum’, hence the change to AVS as a ‘word’ much like IBM doesn’t refer to itself by its original name, International Business Machines.

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.

Art (Lawren Harris and the Group of Seven), science (Raman spectroscopic examinations), and other collisions at the 2014 Canadian Chemistry Conference (part 4 of 4)

Cultural heritage and the importance of pigments and databases

Unlike Thom (Ian Thom, curator at the Vancouver Art Gallery), I believe that the testing was important. Knowing the spectra emitted by the pigments in Hurdy Gurdy and Autumn Harbour could help to set benchmarks for establishing the authenticity of the pigments used by artists (Harris and others) in the early part of Canada’s 20th century.

Europeans and Americans are more advanced in their use of technology as a tool in the process of authenticating, restoring, or conserving a piece of art. At the Chicago Institute of Art they identified the red pigment used in a Renoir painting as per my March 24, 2014 posting,

… The first item concerns research by Richard Van Duyne into the nature of the red paint used in one of Renoir’s paintings. A February 14, 2014 news item on Azonano describes some of the art conservation work that Van Duyne’s (nanoish) technology has made possible along with details about this most recent work,

Scientists are using powerful analytical and imaging tools to study artworks from all ages, delving deep below the surface to reveal the process and materials used by some of the world’s greatest artists.

Northwestern University chemist Richard P. Van Duyne, in collaboration with conservation scientists at the Art Institute of Chicago, has been using a scientific method he discovered nearly four decades ago to investigate masterpieces by Pierre-Auguste Renoir, Winslow Homer and Mary Cassatt.

Van Duyne recently identified the chemical components of paint, now partially faded, used by Renoir in his oil painting “Madame Léon Clapisson.” Van Duyne discovered the artist used carmine lake, a brilliant but light-sensitive red pigment, on this colorful canvas. The scientific investigation is the cornerstone of a new exhibition at the Art Institute of Chicago.

There are some similarities between the worlds of science (in this case, chemistry) and art (collectors,  institutions, curators, etc.). They are worlds where one must be very careful.

The scientists/chemists choose their words with precision while offering no certainties. Even the announcement for the discovery (by physicists) of the Higgs Boson is not described in absolute terms as I noted in my July 4, 2012 posting titled: Tears of joy as physicists announce they’re pretty sure they found the Higgs Boson. As the folks from ProsPect Scientific noted,

This is why the science must be tightly coupled with art expertise for an effective analysis.  We cannot do all of that for David [Robertson]. [He] wished to show a match between several pigments to support an interpretation that the ‘same’ paints were used. The availability of Hurdy Gurdy made this plausible because it offered a known benchmark that lessened our dependency on the databases and art-expertise. This is why Raman spectroscopy more often disproves authenticity (through pigment anachronisms). Even if all of the pigments analysed showed the same spectra we don’t know that many different painters didn’t buy the same brand of paint or that some other person didn’t take those same paints and use them for a different painting. Even if all pigments were different, that doesn’t mean Lawren Harris didn’t paint it, it just means different paints were used.

In short they proved that one of the pigments used in Autumn Harbour was also used in the authenticated Harris, Hurdy Gurdy, and the other pigment was in use at that time (early 20th century) in Canada. It doesn’t prove it’s a Harris painting but, unlike the Pollock painting where they found an anachronistic pigment, it doesn’t disprove Robertson’s contention.

To contrast the two worlds, the art world seems to revel in secrecy for its own sake while the world of science (chemistry) will suggest, hint, or hedge but never state certainties. The ProSpect* Scientific representative commented on authentication, art institutions, and databases,

We know that some art institutions are extremely cautious about any claims towards authentication, and they decline to be cited in anything other than the work they directly undertake. (One director of a well known US art institution said to me that they pointedly do not authenticate works, she offered advice on how to conduct the analysis but declined any reference to her institution.) We cannot comment on any of the business plans of any of our customers but the customers we have that use Raman spectroscopy on paintings generally build databases from their collected studies as a vital tool to their own ongoing work collecting and preserving works of art.

We don’t know of anyone with a database particular to pigments used by Canadian artists and neither did David R. We don’t know that any organization is developing such a database.The database we used is a mineral database (as pigments in the early 20th century were pre-synthetic this database contains some of the things commonly used in pigments at that time) There are databases available for many things:  many are for sale, some are protected intellectual property. We don’t have immediate access to a pigments database. Some of our art institution/museum customers are developing their own but often these are not publicly available. Raman spectroscopy is new on the scene relative to other techniques like IR and X-Ray analysis and the databases of Raman spectra are less mature.


Canadian cultural heritage

Whether or not Autumn Harbour is a Lawren Harris painting may turn out to be less important than establishing a means for better authenticating, restoring, and conserving Canadian cultural heritage. (In a June 13, 2014 telephone conversation, David Robertson claims he will forward the summary version of the data from the tests to the Canadian Conservation Institute once it is received.)

If you think about it, Canadians are defined by the arts and by research. While our neighbours to the south went through a revolutionary war to declare independence, Canadians have declared independence through the visual and literary arts and the scientific research and implementation of technology (transportation and communication in the 19th and 20th centuries).

Thank you to both Tony Ma and David Robertson.

Finally, Happy Canada Day on July 1, 2014!

Part 1

Part 2

Part 3

* ‘ProsPect’ changed to ‘ProSpect’ on June 30, 2014.

ETA July 14, 2014 at 1300 hours PDT: There is now an addendum to this series, which features a reply from the Canadian Conservation Institute to a query about art pigments used by Canadian artists and access to a database of information about them.

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

Art (Lawren Harris and the Group of Seven), science (Raman spectroscopic examinations), and other collisions at the 2014 Canadian Chemistry Conference (part 3 of 4)

Dramatic headlines (again)

Ignoring the results entirely, Metro News Vancouver, which favours the use of the word ‘fraud’, featured it in the headline of a second article about the testing, “Alleged Group of Seven work a fraud: VAG curator” by Thandi Fletcher (June 5, 2014 print issue); happily the online version of Fletcher’s story has had its headline changed to the more accurate: “Alleged Group of Seven painting not an authentic Lawren Harris, says Vancouver Art Gallery curator.” Fletcher’s article was updated after its initial publication with some additional text (it is worth checking out the online version even if you’re already seen the print version). There had been a second Vancouver Metro article on the testing of the authenticated painting by Nick Wells but that in common, with his June 4, 2014 article about the first test, “A fraud or a find?” is no longer available online. Note: Standard mainstream media practice is that the writer with the byline for the article is not usually the author of the article’s headline.

There are two points to be made here. First, Robertson has not attempted to represent ‘Autumn Harbour’ as an authentic Lawren Harris painting other than in a misguided headline for his 2011 news release.  From Robertson’s July 26, 2011 news release (published by Reuters and published by Market Wired) where he crossed a line by stating that Autumn Harbour is a Harris in his headline (to my knowledge the only time he’s done so),

Lost Lawren Harris Found in Bala, Ontario

Unknown 24×36 in. Canvas Piques a Storm of Controversy

VANCOUVER, BRITISH COLUMBIA–(Marketwire – July 26, 2011) –
Was Autumn Harbour painted by Lawren Harris in the fall of 1912? That summer Lawren Harris was 26 years old and had proven himself as an accomplished and professional painter. He had met J.E.H. MacDonald in November of 1911. They became fast friends and would go on to form the Group of Seven in 1920 but now in the summer of 1912 they were off on a sketching expedition to Mattawa and Temiscaming along the Quebec-Ontario border. Harris had seen the wilderness of the northern United States and Europe but this was potentially his first trip outside the confines of an urban Toronto environment into the Canadian wilderness.

By all accounts he was overwhelmed by what he saw and struggled to find new meaning in his talents that would capture these scenes in oil and canvas. There are only two small works credited to this period, archived in the McMichael gallery in Kleinburg, Ontario. Dennis Reid, Assistant Curator of the National Gallery of Canada stated in 1970 about this period: “Both Harris and (J.E.H.) MacDonald explored new approaches to handling of colour and overall design in these canvases. Harris in particular was experimenting with new methods of paint handling, and Jackson pointed out the interest of the other painters in these efforts, referring to the technique affectionately as ‘Tomato Soup’.” For most authorities the summer and fall of 1912 are simply called his ‘lost period’ because it was common for Harris to destroy, abandon or give away works that did not meet his standards. The other trait common to Harris works, is the lack of a signature and some that are signed were signed on his behalf. The most common proxy signatory was Betsy Harris, his second wife who signed canvases on his behalf when he could no longer do so.

So the question remains. Can an unsigned 24×36 in. canvas dated to 1900-1920 that was found in a curio shop in Bala, Ontario be a long lost Lawren Harris? When pictures were shown to Charles C. Hill, Curator of Canadian Art, National Gallery of Canada, he replied: “The canvas looks like no Harris I have ever seen…” A similar reply also came from Ian Thom, Head Curator for the Vancouver Art Gallery: “I do not believe that your work can be connected with Harris in any way.” [emphases mine] Yet the evidence still persists. The best example resides within the National Art Gallery. A 1919, 50.5 X 42.5 in. oil on rough canvas shows Harris’s style of under painting, broad brush strokes and stilled composition. Shacks, painted in 1919 and acquired the Gallery in 1920 is an exact technique clone of Autumn Harbour. For a list of comparisons styles with known Harris works and a full list of the collected evidence please consult www.1912lawrenharris.ca/ and see for yourself.

If Robertson was intent on perpetrating a fraud, why would he include the negative opinions from the curators or attempt to authenticate his purported Harris? The 2011 website is no longer available but Robertson has established another website, http://autumnharbour.ca/.

It’s not a crime (fraud) to have strong or fervent beliefs. After all, Robertson was the person who contacted ProSpect* Scientific to arrange for a test.

Second, Ian Thom, the VAG curator did not call ‘Autumn Harbour’ or David Robertson, a fraud. From the updated  June 5, 2014 article sporting a new headline by Thandi Fletcher,

“I do not believe that the painting … is in fact a Lawren Harris,” said Ian Thom, senior curator at the Vancouver Art Gallery, “It’s that simple.”

It seems Thom feels as strongly as Robertson does; it’s just that Thom holds an opposing opinion.

Monetary value was mentioned earlier as an incentive for Robertson’s drive to prove the authenticity of his painting, from the updated June 5, 2014 article with the new headline by Thandi Fletcher,

Still, Robertson, who has carried out his own research on the painting, said he is convinced the piece is an authentic Harris. If it were, he said it would be worth at least $3 million. [emphasis mine]

“You don’t have to have a signature on the canvas to recognize brushstroke style,” he said.

Note: In a June 13, 2014 telephone conversation, Robertson used the figure of $1M to denote his valuation of Autumn Harbour and claimed a degree in Geography with a minor in Fine Arts from the University of Waterloo. He also expressed the hope that Autumn Harbour would prove to be a* Rosetta Stone of sorts for art pigments used in the early part of the 20th century.

As for the owner of Hurdy Gurdy and the drama that preceded its test on June 4, 2014, Fletcher had this in her updated and newly titled article,

Robertson said the painting’s owner, local Vancouver businessman Tony Ma, had promised to bring the Harris original to the chemistry conference but pulled out after art curator Thom told him not to participate.

While Thom acknowledged that Ma did ask for his advice, he said he didn’t tell him to pull out of the conference.

“It was more along the lines of, ‘If I were you, I wouldn’t do it, because I don’t think it’s going to accomplish anything,’” said Thom, adding that the final decision is up to Ma. [emphasis mine]

A request for comment from Ma was not returned Wednesday [June 5, 2014].

Thom, who already examined Robertson’s painting a year ago [in 2013? then, how is he quoted in a 2011 news release?], said he has no doubt Harris did not paint it.

“The subject matter is wrong, the handling of the paint is wrong, and the type of canvas is wrong,” he said, adding that many other art experts agree with him.

Part 1

Part 2

Part 4

* ‘ProsPect’ changed to ‘ProSpect’ on June 30, 2014. Minor grammatical change made to sentence: ‘He also expressed the hope that Autumn Harbour would prove to a be of Rosetta Stone of sorts for art pigments used in the early part of the 20th century.’ to ‘He also expressed the hope that Autumn Harbour would prove to be a* Rosetta Stone of sorts for art pigments used in the early part of the 20th century.’ on July 2, 2014.

ETA July 14, 2014 at 1300 hours PDT: There is now an addendum to this series, which features a reply from the Canadian Conservation Institute to a query about art pigments used by Canadian artists and access to a database of information about them.

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

Art (Lawren Harris and the Group of Seven), science (Raman spectroscopic examinations), and other collisions at the 2014 Canadian Chemistry Conference (part 2 of 4)

Testing the sample and Raman fingerprints

The first stage of the June 3, 2010 test of David Robertson’s Autumn Harbour, required taking a tiny sample from the painting,. These samples are usually a fleck of a few microns (millionths of an inch), which can then be tested to ensure the lasers are set at the correct level assuring no danger of damage to the painting. (Robertson extracted the sample himself prior to arriving at the conference. He did not allow anyone else to touch his purported Harris before, during, or after the test.)

Here’s how ProSpect* Scientific describes the ‘rehearsal’ test on the paint chip,

Tests on this chip were done simply to ensure we knew what power levels were safe for use on the painting.  While David R stated he believed the painting was oil on canvas without lacquer, we were not entirely certain of that.  Lacquer tends to be easier to burn than oil pigments and so we wanted to work with this chip just to be entirely certain there was no risk to the painting itself.

The preliminary (rehearsal) test resulted in a line graph that showed the frequencies of the various pigments in the test sample. Titanium dioxide, for example, was detected and its frequency (spectra) reflected on the graph.

I found this example of a line graph representing the spectra (fingerprint) for a molecule of an ultramarine (blue) pigment along with a general explanation of a Raman ‘fingerprint’. There is no indication as to where the ultramarine pigment was obtained. From the  WebExhibits.org website featuring a section on Pigments through the Ages and a webpage on Spectroscopy,


Ultramarine [downloaded from http://www.webexhibits.org/pigments/intro/spectroscopy.html]

Raman spectra consist of sharp bands whose position and height are characteristic of the specific molecule in the sample. Each line of the spectrum corresponds to a specific vibrational mode of the chemical bonds in the molecule. Since each type of molecule has its own Raman spectrum, this can be used to characterize molecular structure and identify chemical compounds.

Most people don’t realize that the chemical signature (spectra) for pigment can change over time with new pigments being introduced. Finding a pigment that was on the market from 1970 onwards in a painting by Jackson Pollock who died in 1956 suggests strongly that the painting couldn’t have come from Pollock’s hand. (See Michael Shnayerson’s May 2012 article, A Question of Provenance, in Vanity Fair for more about the Pollock painting. The article details the fall of a fabled New York art gallery that had been in business prior to the US Civil War.)

The ability to identify a pigment’s molecular fingerprint means that an examination by Raman spectroscopy can be part of an authentication, a restoration, or a conservation process. Here is how a representative from ProSpect Scientific describes the process,

Raman spectroscopy is non-destructive (when conducted at the proper power levels) and identifies the molecular components in the pigments, allowing characterization of the pigments for proper restoration or validation by comparison with other pigments of the same place/time. It is valuable to art institutions and conservators because it can do this.  In most cases of authentication Raman spectroscopy is one of many tools used and not the first in line. A painting would be first viewed by art experts for technique, format etc, then most often analysed with IR or X-Ray, then perhaps Raman spectroscopy. It is impossible to use Raman spectroscopy to prove authenticity as paint pigments are usually not unique to any particular painter.  Most often Raman spectroscopy is used by conservators to determine proper pigments for appropriate restoration.  Sometimes Raman will tell us that the pigment isn’t from the time/era the painting is purported to be from (anachronisms).

Autumn Harbour test

Getting back to the June 3, 2014 tests, once the levels were set then it was time to examine Autumn Harbour itself to determine the spectra for the various pigments.  ProSpect Scientific has provided an explanation of the process,

This spectrometer was equipped with an extension that allowed delivery of the laser and collection of the scattered light at a point other than directly under the microscope. We could also have used a flexible fibre optic probe for this, but this device is slightly more efficient. This allowed us to position the delivery/collection point for the light just above the painting at the spot we wished to test. For this test, we don’t sweep across the surface, we test a small pinpoint that we feel is a pigment of the target colour.

We only use one laser at a time. The system is built so we can easily select one laser or another, depending on what we wish to look at. Some researchers have 3 or 4 lasers in their system because different lasers provide a better/worse raman spectrum depending on the nature of the sample. In this case we principally used the 785nm laser as it is better for samples that exhibit fluorescence at visible wavelengths. 532nm is a visible wavelength.  For samples that didn’t produce good signal we tried the 532nm laser as it produces better signal to noise than 785nm, generally speaking. I believe the usable results in our case were obtained with the 785nm laser.

The graphed Raman spectra shows peaks for the frequency of scattered light that we collect from the laser-illuminated sample (when shining a laser on a sample the vast majority of light is scattered in the same frequency of the laser, but a very small amount is scattered at different frequencies unique to the molecules in the sample). Those frequencies correspond to and identify molecules in the sample. We use a database (on the computer attached to the spectrometer) to pattern match the spectra to identify the constituents.

One would have thought ‘game over’ at this point. 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 (CCI) has a very small database of pigments and nothing from Lawren Harris paintings [See the CCI’s response in this addendum], so the chances that David Robertson would have been able to find a record of pigments used by Lawren Harris roughly in the same time period that Autumn Harbour seems to have been painted are not good.

Everything changes

In a stunning turn of events and despite the lack of enthusiasm from Vancouver Art Gallery (VAG) curator, Ian Thom, on Wednesday, June 4, 2014 the owner of the authenticated Harris, Hurdy Gurdy, relented and brought the painting in for tests.

Here’s what the folks from ProSpect Scientific had to say about the comparison,

Many pigments were evaluated. Good spectra were obtained for blue and white. The blue pigment matched on both paintings, the white didn’t match. We didn’t get useful Raman spectra from other pigments. We had limited time, with more time we might fine tune and get more data.

One might be tempted to say that the results were 50/50 with one matching and the other not, The response from the representative of ProSpect Scientific is more measured,

We noted that the mineral used in the pigment was the same.  Beyond that is interpretation:  Richard offered the view that lapis-lazuli was a typical and characteristic component for blue in that time period (early 1900’s).   We saw different molecules in the whites used in the two paintings, and Richard offered that both were characteristic of the early 1900’s.

Part 1

Part 3

Part 4

* ‘ProsPect’ changed to ‘ProSpect’ on June 30, 2014.

ETA July 14, 2014 at 1300 hours PDT: There is now an addendum to this series, which features a reply from the Canadian Conservation Institute to a query about art pigments used by Canadian artists and access to a database of information about them.

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


Art (Lawren Harris and the Group of Seven), science (Raman spectroscopic examinations), and other collisions at the 2014 Canadian Chemistry Conference (part 1 of 4)

One wouldn’t expect the 97th Canadian Chemistry Conference held in Vancouver, Canada from  June 1 – 5, 2014 to be an emotional rollercoaster. One would be wrong. Chemists and members of the art scene are not only different from thee and me, they are different from each other.

Setting the scene

It started with a May 30, 2014 Simon Fraser University (SFU) news release,

During the conference, ProSpect Scientific has arranged for an examination of two Canadian oil paintings; one is an original Lawren Harris (Group of Seven) titled “Hurdy Gurdy” while the other is a painting called “Autumn Harbour” that bears many of Harris’s painting techniques. It was found in Bala, Ontario, an area that was known to have been frequented by Harris.

Using Raman Spectroscopy equipment manufactured by Renishaw (Canada), Dr. Richard Bormett will determine whether the paint from both works of art was painted from the same tube of paint.

As it turns out, the news release got it somewhat wrong. Raman spectroscopy testing does not make it possible to* determine whether the paints came from the same tube, the same batch, or even the same brand. Nonetheless, it is an important tool for art authentication, restoration and/or conservation and both paintings were scheduled for testing on Tuesday, June 3, 2014. But that was not to be.

The owner of the authenticated Harris (Hurdy Gurdy) rescinded permission. No one was sure why but the publication of a June 2, 2014 article by Nick Wells for Metro News Vancouver probably didn’t help in a situation that was already somewhat fraught. The print version of the Wells article titled, “A fraud or a find?” showed only one painting “Hurdy Gurdy” and for anyone reading quickly, it might have seemed that the Hurdy Gurdy painting was the one that could be “a fraud or a find.”

The dramatically titled article no longer seems to be online but there is one (also bylined by Nick Wells) dated June 1, 2014 titled, Chemists in Vancouver to use lasers to verify Group of Seven painting. It features (assuming it is still available online) images of both paintings, the purported Harris (Autumn Harbour) and the authenticated Harris (Hurdy Gurdy),

"Autumn Harbour" [downloaded from http://metronews.ca/news/vancouver/1051693/chemists-in-vancouver-to-use-lasers-to-verify-group-of-seven-painting/]

“Autumn Harbour” [downloaded from http://metronews.ca/news/vancouver/1051693/chemists-in-vancouver-to-use-lasers-to-verify-group-of-seven-painting/]

Heffel Fine Art Auction

Lawren Harris’‚ Hurdy Gurdy, a depiction of Toronto’s Ward district is shown in this handout image. [downloaded from http://metronews.ca/news/vancouver/1051693/chemists-in-vancouver-to-use-lasers-to-verify-group-of-seven-painting/]

David Robertson who owns the purported Harris (Autumn Harbour) and is an outsider vis à vis the Canadian art world, has been trying to convince people for years that the painting he found in Bala, Ontario is a “Lawren Harris” painting. For anyone unfamiliar with the “Group of Seven” of which Lawren Harris was a founding member, this group is legendary to many Canadians and is the single most recognized name in Canadian art history (although some might argue that status for Emily Carr and/or Tom Thomson; both of whom have been, on occasion, honorarily included in the Group).  Robertson’s incentive to prove “Autumn Harbour” is a Harris could be described as monetary and/or prestige-oriented and/or a desire to make history.

The owner of the authenticated Harris “Hurdy Gurdy” could also be described as an outsider of sorts [unconfirmed at the time of publication; a June 26, 2014 query is outstanding], gaining entry to that select group of people who own a ‘Group of Seven’ painting at a record-setting price in 2012 with the purchase of a piece that has a provenance as close to unimpeachable as you can get. From a Nov. 22, 2012 news item on CBC (Canadian Broadcasting Corporation) news online,

Hurdy Gurdy, one of the finest urban landscapes ever painted by Lawren Harris, sold for $1,082,250, a price that includes a 17 per cent buyer’s premium. The pre-sale estimate suggested it could go for $400,000 to $600,000 including the premium.

The Group of Seven founder kept the impressionistic painting of a former Toronto district known as the Ward in his own collection before bequeathing it to his daughter. It has remained in the family ever since.

Occasionally, Harris “would come and say, ‘I need to borrow this back for an exhibition,’ and sometimes she wouldn’t see [the paintings] again,” Heffel vice-president Robert Heffel said. “Harris asked to have this painting back for a show…and she said ‘No, dad. Not this one.’ It was a painting that was very, very dear to her.”

It had been a coup to get access to an authenticated Harris for comparison testing so Hurdy Gurdy’s absence was a major disappointment. Nonetheless, Robertson went through with the scheduled June 3, 2014 testing of his ‘Autumn Harbour’.

Chemistry, spectroscopy, the Raman system, and the experts

Primarily focused on a technical process, the chemists (from ProSpect* Scientific and Renishaw) were unprepared for the drama and excitement that anyone associated with the Canadian art scene might have predicted.  From the chemists’ perspective, it was an opportunity to examine a fabled piece of Canadian art (Hurdy Gurdy) and, possibly, play a minor role in making Canadian art history.

The technique the chemists used to examine the purported Harris, Autumn Harbour, is called Raman spectroscopy and its beginnings as a practical technique date back to the 1920s. (You can get more details about Raman spectroscopy in this Wikiipedia entry then will be given here after the spectroscopy description.)

Spectroscopy (borrowing heavily from this Wikipedia entry) is the process where one studies the interaction between matter and radiated energy and which can be measured as frequencies and/or wavelengths. Raman spectroscopy systems can be used to examine radiated energy with low frequency emissions as per this description in the Raman spectroscopy Wikipedia entry,

Raman spectroscopy (/ˈrɑːmən/; named after Sir C. V. Raman) is a spectroscopic technique used to observe vibrational, rotational, and other low-frequency modes in a system.[1] It relies on inelastic scattering, or Raman scattering, of monochromatic light, usually from a laser in the visible, near infrared, or near ultraviolet range. The laser light interacts with molecular vibrations, phonons or other excitations in the system, resulting in the energy of the laser photons being shifted up or down.

The reason for using Raman spectroscopy for art authentication, conservation, and/or restoration purposes is that the technique, as noted earlier, can specify the specific chemical composition of the pigments used to create the painting. It is a technique used in many fields as a representative from ProSpect Scientific notes,

Raman spectroscopy is a vital tool for minerologists, forensic investigators, surface science development, nanotechnology research, pharmaceutical research and other applications.  Most graduate level university labs have this technology today, as do many government and industry researchers.  Raman spectroscopy is now increasingly available in single purpose hand held units that can identify the presence of a small number of target substances with ease-of-use appropriate for field work by law enforcers, first responders or researchers in the field.

About the chemists and ProSpect Scientific and Renishaw

There were two technical experts attending the June 3, 2014 test for the purported Harris painting, Autumn Harbour, Dr. Richard Bormett of Renishaw and Dr. Kelly Akers of ProSpect Scientific.

Dr. Kelly Akers founded ProSpect Scientific in 1996. Her company represents Renishaw Raman spectroscopy systems for the most part although other products are also represented throughout North America. Akers’ company is located in Orangeville, Ontario. Renishaw, a company based in the UK. offers a wide line of products including Raman spectroscopes. (There is a Renishaw Canada Ltd., headquartered in Mississauga, Ontario, representing products other than Raman spectroscopes.)

ProSpect Scientific runs Raman spectroscopy workshops, at the Canadian Chemistry Conferences as a regular occurrence, often in conjunction with Renishaw’s Bormett,. David Robertson, on learning the company would be at the 2014 Canadian Chemistry Conference in Vancouver, contacted Akers and arranged to have his purported Harris and Hurdy Gurdy, the authenticated Harris, tested at the conference.

Bormett, based in Chicago, Illinois, is Renishaw’s business manager for the Spectroscopy Products Division in North America (Canada, US, & Mexico).  His expertise as a spectroscopist has led him to work with many customers throughout the Americas and, as such, has worked with several art institutions and museums on important and valuable artifacts.  He has wide empirical knowledge of Raman spectra for many things, including pigments, but does not claim expertise in art or art authentication. You can hear him speak at a 2013 US Library of Congress panel discussion titled, “Advances in Raman Spectroscopy for Analysis of Cultural Heritage Materials,” part of the Library of Congress’s Topics in Preservation Series (TOPS), here on the Library of Congress website or here on YouTube. The discussion runs some 130 minutes.

Bormett has a PhD in analytical chemistry from the University of Pittsburgh. Akers has a PhD in physical chemistry from the University of Toronto and is well known in the Raman spectroscopy field having published in many refereed journals including “Science” and the “Journal of Physical Chemistry.”  She expanded her knowledge of industrial applications of Raman spectroscopy substantive post doctoral work in Devon, Alberta at the CANMET Laboratory (Natural Resources Canada).

About Renishaw InVia Reflex Raman Spectrometers

The Raman spectroscopy system used for the examination, a Renishaw InVia Reflex Raman Spectrometer, had

  • two lasers (using 785nm [nanometres] and 532nm lasers for this application),
  • two cameras,
    (ProSpect Scientific provided this description of the cameras: The system has one CCD [Charged Coupled Device] camera that collects the scattered laser light to produce Raman spectra [very sensitive and expensive]. The system also has a viewing camera mounted on the microscope to allow the user to visually see what the target spot on the sample looks like. This camera shows on the computer what is visible through the eyepieces of the microscope.)
  • a microscope,
  • and a computer with a screen,

all of which fit on a tabletop, albeit a rather large one.

For anyone unfamiliar with the term CCD (charged coupled device), it is a sensor used in cameras to capture light and convert it to digital data for capture by the camera. (You can find out more here at TechTerms.com on the CCD webpage.)

Part 2

Part 3

Part 4

* ‘to’ added to sentence on June 27, 2014 at 1340 hours (PDT). ‘ProsPect’ corrected to ‘ProSpect’ on June 30, 2014.

ETA July 14, 2014 at 1300 hours PDT: There is now an addendum to this series, which features a reply from the Canadian Conservation Institute to a query about art pigments used by Canadian artists and access to a database of information about them.

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