Tag Archives: cultural heritage

Europe’s cathedrals get a ‘lift’ with nanoparticles

That headline is a teensy bit laboured but I couldn’t resist the levels of wordplay available to me. They’re working on a cathedral close to the leaning Tower of Pisa in this video about the latest in stone preservation in Europe.

I have covered the topic of preserving stone monuments before (most recently in my Oct. 21, 2014 posting). The action in this field seems to be taking place mostly in Europe, specifically Italy, although other countries are also quite involved.

Finally, getting to the European Commission’s latest stone monument preservation project, Nano-Cathedral, a Sept. 26, 2017 news item on Nanowerk announces the latest developments,

Just a few meters from Pisa’s famous Leaning Tower, restorers are defying scorching temperatures to bring back shine to the city’s Cathedral.

Ordinary restoration techniques like laser are being used on much of the stonework that dates back to the 11th century. But a brand new technique is also being used: a new material made of innovative nanoparticles. The aim is to consolidate the inner structure of the stones. It’s being applied mainly on marble.

A March 7, 2017 item on the Euro News website, which originated the Nanowerk news item, provides more detail,

“Marble has very low porosity, which means we have to use nanometric particles in order to go deep inside the stone, to ensure that the treatment is both efficient while still allowing the stone to breathe,” explains Roberto Cela, civil engineer at Opera Della Primaziale Pisana.

The material developed by the European research team includes calcium carbonate, which is a mix of calcium oxide, water and carbon dioxide.

The nano-particles penetrate the stone cementing its decaying structure.

“It is important that these particles have the same chemical nature as the stones that are being treated, so that the physical and mechanical processes that occur over time don’t lead to the break-up of the stones,” says Dario Paolucci, chemist at the University of Pisa.

Vienna’s St Stephen’s is another of the five cathedrals where the new restoration materials are being tested.

The first challenge for researchers is to determine the mechanical characteristics of the cathedral’s stones. Since there are few original samples to work on, they had to figure out a way of “ageing” samples of stones of similar nature to those originally used.

“We tried different things: we tried freeze storage, we tried salts and acids, and we decided to go for thermal ageing,” explains Matea Ban, material scientist at the University of Technology in Vienna. “So what happens is that we heat the stone at certain temperatures. Minerals inside then expand in certain directions, and when they expand they build up stresses to neighbouring minerals and then they crack, and we need those cracks in order to consolidate them.”

Consolidating materials were then applied on a variety of limestones, sandstones and marble – a selection of the different types of stones that were used to build cathedrals around Europe.

What researchers are looking for are very specific properties.

“First of all, the consolidating material has to be well absorbed by the stone,” says petrologist Johannes Weber of the University of Applied Arts in Vienna. “Then, as it evaporates, it has to settle properly within the stone structure. It should not shrink too much. All materials shrink when drying, including consolidating materials. They should adhere to the particles of the stone but shouldn’t completely obstruct its pores.”

Further tests are underway in cathedrals across Europe in the hope of better protecting our invaluable cultural heritage.

There’s a bit more detail about Nano-Cathedral on the Opera della Primaziale Pisana (O₽A) website (from their Nano-Cathedral project page),

With the meeting of June 3 this year the Nano Cathedral project kicked off, supported by the European Union within the nanotechnology field applied to Horizon 2020 cultural heritage with a fund of about 6.5 million euro.

A total of six monumental buildings will be for three years under the eyes and hands of petrographers, geologists, chemists and restorers of the institutes belonging to the Consortium: five cathedrals have been selected to represent the cultural diversity within Europe from the perspective of developing shared values and transnational identity, and a contemporary monumental building entirely clad in Carrara marble, the Opera House of Oslo.

Purpose: the testing of nanomaterials for the conservation of marble and the outer surfaces of our ‘cathedrals’.
The field of investigation to check degradation, testing new consolidating and protective products is the Cathedral of Pisa together with the Cathedrals of Cologne, Vienna, Ghent and Vitoria.
For the selection of case studies we have crosschecked requirements for their historical and architectural value but also for the different types of construction materials – marble, limestone and sandstone – as well as the relocation of six monumental buildings according to European climates.

The Cathedral of Pisa is the most southern, fully positioned in Mediterranean climate, therefore subject to degradation and very different from those which the weather conditions of the Scandinavian peninsula recorded; all the intermediate climate phases are modulated through Ghent, Vitoria, Cologne and Vienna.

At the conclusion of the three-year project, once the analysis in situ and in the laboratory are completed and all the experiments are tested on each different identified portion in each monumental building, an intervention protocol will be defined in detail in order to identify the mineralogical and petrographic characteristics of stone materials and of their degradation, the assessment of the causes and mechanisms of associated alteration, including interactions with factors of environmental pollution. Then we will be able to identify the most appropriate method of restoration and testing of nanotechnology products for the consolidation and protection of different stone materials.

In 2018 we hope to have new materials to protect and safeguard the ‘skin’ of our historic buildings and monuments for a long time.

Back to my headline and the second piece of wordplay, ‘lift’ as in ‘skin lift’ in that last sentence.

I realize this is a bit off topic but it’s worth taking a look at ORA’s home page,

Gabriele D’Annunzio effectively condenses the wonder and admiration that catch whoever visits the Duomo Square of Pisa.

The Opera della Primaziale Pisana (O₽A) is a non-profit organisation which was established in order to oversee the first works for the construction of the monuments in the Piazza del Duomo, subject to its own charter which includes the protection, promotion and enhancement of its heritage, in order to pass the religious and artistic meaning onto future generations.

«L’Ardea roteò nel cielo di Cristo, sul prato dei Miracoli.»
Gabriele d’Annunzio in Forse che sì forse che no (1910)

If you go to the home page, you can buy tickets to visit the monuments surrounding the square and there are other notices including one for a competition (it’s too late to apply but the details are interesting) to construct four stained glass windows for the Pisa cathedral.

World heritage music stored in DNA

It seems a Swiss team from the École Polytechnique de Lausanne (EPFL) have collaborated with American companies Twist Bioscience and Microsoft, as well as, the University of Washington (state) to preserve two iconic jazz pieces on DNA (deoxyribonucleic acid) according to a Sept. 29, 2017 news item on phys.org,,

Thanks to an innovative technology for encoding data in DNA strands, two items of world heritage – songs recorded at the Montreux Jazz Festival [held in Switzerland] and digitized by EPFL – have been safeguarded for eternity. This marks the first time that cultural artifacts granted UNESCO heritage status have been saved in such a manner, ensuring they are preserved for thousands of years. The method was developed by US company Twist Bioscience and is being unveiled today in a demonstrator created at the EPFL+ECAL Lab.

“Tutu” by Miles Davis and “Smoke on the Water” by Deep Purple have already made their mark on music history. Now they have entered the annals of science, for eternity. Recordings of these two legendary songs were digitized by the Ecole Polytechnique Fédérale de Lausanne (EPFL) as part of the Montreux Jazz Digital Project, and they are the first to be stored in the form of a DNA sequence that can be subsequently decoded and listened to without any reduction in quality.

A Sept. 29, 2017 EPFL press release by Emmanuel Barraud, which originated the news item, provides more details,

This feat was achieved by US company Twist Bioscience working in association with Microsoft Research and the University of Washington. The pioneering technology is actually based on a mechanism that has been at work on Earth for billions of years: storing information in the form of DNA strands. This fundamental process is what has allowed all living species, plants and animals alike, to live on from generation to generation.

The entire world wide web in a shoe box

All electronic data storage involves encoding data in binary format – a series of zeros and ones – and then recording it on a physical medium. DNA works in a similar way, but is composed of long strands of series of four nucleotides (A, T, C and G) that make up a “code.” While the basic principle may be the same, the two methods differ greatly in terms of efficiency: if all the information currently on the internet was stored in the form of DNA, it would fit in a shoe box!

Recent advances in biotechnology now make it possible for humans to do what Mother Nature has always done. Today’s scientists can create artificial DNA strands, “record” any kind of genetic code on them and then analyze them using a sequencer to reconstruct the original data. What’s more, DNA is extraordinarily stable, as evidenced by prehistoric fragments that have been preserved in amber. Artificial strands created by scientists and carefully encapsulated should likewise last for millennia.

To help demonstrate the feasibility of this new method, EPFL’s Metamedia Center provided recordings of two famous songs played at the Montreux Jazz Festival: “Tutu” by Miles Davis, and “Smoke on the Water” by Deep Purple. Twist Bioscience and its research partners encoded the recordings, transformed them into DNA strands and then sequenced and decoded them and played them again – without any reduction in quality.

The amount of artificial DNA strands needed to record the two songs is invisible to the naked eye, and the amount needed to record all 50 years of the Festival’s archives, which have been included in UNESCO’s [United Nations Educational, Scientific and Cultural Organization] Memory of the World Register, would be equal in size to a grain of sand. “Our partnership with EPFL in digitizing our archives aims not only at their positive exploration, but also at their preservation for the next generations,” says Thierry Amsallem, president of the Claude Nobs Foundation. “By taking part in this pioneering experiment which writes the songs into DNA strands, we can be certain that they will be saved on a medium that will never become obsolete!”

A new concept of time

At EPFL’s first-ever ArtTech forum, attendees got to hear the two songs played after being stored in DNA, using a demonstrator developed at the EPFL+ECAL Lab. The system shows that being able to store data for thousands of years is a revolutionary breakthrough that can completely change our relationship with data, memory and time. “For us, it means looking into radically new ways of interacting with cultural heritage that can potentially cut across civilizations,” says Nicolas Henchoz, head of the EPFL+ECAL Lab.

Quincy Jones, a longstanding Festival supporter, is particularly enthusiastic about this technological breakthrough: “With advancements in nanotechnology, I believe we can expect to see people living prolonged lives, and with that, we can also expect to see more developments in the enhancement of how we live. For me, life is all about learning where you came from in order to get where you want to go, but in order to do so, you need access to history! And with the unreliability of how archives are often stored, I sometimes worry that our future generations will be left without such access… So, it absolutely makes my soul smile to know that EPFL, Twist Bioscience and their partners are coming together to preserve the beauty and history of the Montreux Jazz Festival for our future generations, on DNA! I’ve been a part of this festival for decades and it truly is a magnificent representation of what happens when different cultures unite for the sake of music. Absolute magic. And I’m proud to know that the memory of this special place will never be lost.

A Sept. 29, 2017 Twist Bioscience news release is repetitive in some ways but interesting nonetheless,

Twist Bioscience, a company accelerating science and innovation through rapid, high-quality DNA synthesis, today announced that, working with Microsoft and University of Washington researchers, they have successfully stored archival-quality audio recordings of two important music performances from the archives of the world-renowned Montreux Jazz Festival.
These selections are encoded and stored in nature’s preferred storage medium, DNA, for the first time. These tiny specks of DNA will preserve a part of UNESCO’s Memory of the World Archive, where valuable cultural heritage collections are recorded. This is the first time DNA has been used as a long-term archival-quality storage medium.
Quincy Jones, world-renowned Entertainment Executive, Music Composer and Arranger, Musician and Music Producer said, “With advancements in nanotechnology, I believe we can expect to see people living prolonged lives, and with that, we can also expect to see more developments in the enhancement of how we live. For me, life is all about learning where you came from in order to get where you want to go, but in order to do so, you need access to history! And with the unreliability of how archives are often stored, I sometimes worry that our future generations will be left without such access…So, it absolutely makes my soul smile to know that EPFL, Twist Bioscience and others are coming together to preserve the beauty and history of the Montreux Jazz Festival for our future generations, on DNA!…I’ve been a part of this festival for decades and it truly is a magnificent representation of what happens when different cultures unite for the sake of music. Absolute magic. And I’m proud to know that the memory of this special place will never be lost.”
“Our partnership with EPFL in digitizing our archives aims not only at their positive exploration, but also at their preservation for the next generations,” says Thierry Amsallem, president of the Claude Nobs Foundation. “By taking part in this pioneering experiment which writes the songs into DNA strands, we can be certain that they will be saved on a medium that will never become obsolete!”
The Montreux Jazz Digital Project is a collaboration between the Claude Nobs Foundation, curator of the Montreux Jazz Festival audio-visual collection and the École Polytechnique Fédérale de Lausanne (EPFL) to digitize, enrich, store, show, and preserve this notable legacy created by Claude Nobs, the Festival’s founder.
In this proof-of-principle project, two quintessential music performances from the Montreux Jazz Festival – Smoke on the Water, performed by Deep Purple and Tutu, performed by Miles Davis – have been encoded onto DNA and read back with 100 percent accuracy. After being decoded, the songs were played on September 29th [2017] at the ArtTech Forum (see below) in Lausanne, Switzerland. Smoke on the Water was selected as a tribute to Claude Nobs, the Montreux Jazz Festival’s founder. The song memorializes a fire and Funky Claude’s rescue efforts at the Casino Barrière de Montreux during a Frank Zappa concert promoted by Claude Nobs. Miles Davis’ Tutu was selected for the role he played in music history and the Montreux Jazz Festival’s success. Miles Davis died in 1991.
“We archived two magical musical pieces on DNA of this historic collection, equating to 140MB of stored data in DNA,” said Karin Strauss, Ph.D., a Senior Researcher at Microsoft, and one of the project’s leaders.  “The amount of DNA used to store these songs is much smaller than one grain of sand. Amazingly, storing the entire six petabyte Montreux Jazz Festival’s collection would result in DNA smaller than one grain of rice.”
Luis Ceze, Ph.D., a professor in the Paul G. Allen School of Computer Science & Engineering at the University of Washington, said, “DNA, nature’s preferred information storage medium, is an ideal fit for digital archives because of its durability, density and eternal relevance. Storing items from the Montreux Jazz Festival is a perfect way to show how fast DNA digital data storage is becoming real.”
Nature’s Preferred Storage Medium
Nature selected DNA as its hard drive billions of years ago to encode all the genetic instructions necessary for life. These instructions include all the information necessary for survival. DNA molecules encode information with sequences of discrete units. In computers, these discrete units are the 0s and 1s of “binary code,” whereas in DNA molecules, the units are the four distinct nucleotide bases: adenine (A), cytosine (C), guanine (G) and thymine (T).
“DNA is a remarkably efficient molecule that can remain stable for millennia,” said Bill Peck, Ph.D., chief technology officer of Twist Bioscience.  “This is a very exciting project: we are now in an age where we can use the remarkable efficiencies of nature to archive master copies of our cultural heritage in DNA.   As we develop the economies of this process new performances can be added any time.  Unlike current storage technologies, nature’s media will not change and will remain readable through time. There will be no new technology to replace DNA, nature has already optimized the format.”
DNA: Far More Efficient Than a Computer 
Each cell within the human body contains approximately three billion base pairs of DNA. With 75 trillion cells in the human body, this equates to the storage of 150 zettabytes (1021) of information within each body. By comparison, the largest data centers can be hundreds of thousands to even millions of square feet to hold a comparable amount of stored data.
The Elegance of DNA as a Storage Medium
Like music, which can be widely varied with a finite number of notes, DNA encodes individuality with only four different letters in varied combinations. When using DNA as a storage medium, there are several advantages in addition to the universality of the format and incredible storage density. DNA can be stable for thousands of years when stored in a cool dry place and is easy to copy using polymerase chain reaction to create back-up copies of archived material. In addition, because of PCR, small data sets can be targeted and recovered quickly from a large dataset without needing to read the entire file.
How to Store Digital Data in DNA
To encode the music performances into archival storage copies in DNA, Twist Bioscience worked with Microsoft and University of Washington researchers to complete four steps: Coding, synthesis/storage, retrieval and decoding. First, the digital files were converted from the binary code using 0s and 1s into sequences of A, C, T and G. For purposes of the example, 00 represents A, 10 represents C, 01 represents G and 11 represents T. Twist Bioscience then synthesizes the DNA in short segments in the sequence order provided. The short DNA segments each contain about 12 bytes of data as well as a sequence number to indicate their place within the overall sequence. This is the process of storage. And finally, to ensure that the file is stored accurately, the sequence is read back to ensure 100 percent accuracy, and then decoded from A, C, T or G into a two-digit binary representation.
Importantly, to encapsulate and preserve encoded DNA, the collaborators are working with Professor Dr. Robert Grass of ETH Zurich. Grass has developed an innovative technology inspired by preservation of DNA within prehistoric fossils.  With this technology, digital data encoded in DNA remains preserved for millennia.
About UNESCO’s Memory of the World Register
UNESCO established the Memory of the World Register in 1992 in response to a growing awareness of the perilous state of preservation of, and access to, documentary heritage in various parts of the world.  Through its National Commissions, UNESCO prepared a list of endangered library and archive holdings and a world list of national cinematic heritage.
A range of pilot projects employing contemporary technology to reproduce original documentary heritage on other media began. These included, for example, a CD-ROM of the 13th Century Radzivill Chronicle, tracing the origins of the peoples of Europe, and Memoria de Iberoamerica, a joint newspaper microfilming project involving seven Latin American countries. These projects enhanced access to this documentary heritage and contributed to its preservation.
“We are incredibly proud to be a part of this momentous event, with the first archived songs placed into the UNESCO Memory of the World Register,” said Emily Leproust, Ph.D., CEO of Twist Bioscience.
About ArtTech
The ArtTech Foundation, created by renowned scientists and dignitaries from Crans-Montana, Switzerland, wishes to stimulate reflection and support pioneering and innovative projects beyond the known boundaries of culture and science.
Benefitting from the establishment of a favorable environment for the creation of technology companies, the Foundation aims to position itself as key promoter of ideas and innovative endeavors within a landscape of “Culture and Science” that is still being shaped.
Several initiatives, including our annual global platform launched in the spring of 2017, are helping to create a community that brings together researchers, celebrities in the world of culture and the arts, as well as investors and entrepreneurs from Switzerland and across the globe.
About EPFL
EPFL, one of the two Swiss Federal Institutes of Technology, based in Lausanne, is Europe’s most cosmopolitan technical university with students, professors and staff from over 120 nations. A dynamic environment, open to Switzerland and the world, EPFL is centered on its three missions: teaching, research and technology transfer. EPFL works together with an extensive network of partners including other universities and institutes of technology, developing and emerging countries, secondary schools and colleges, industry and economy, political circles and the general public, to bring about real impact for society.
About Twist Bioscience
At Twist Bioscience, our expertise is accelerating science and innovation by leveraging the power of scale. We have developed a proprietary semiconductor-based synthetic DNA manufacturing process featuring a high throughput silicon platform capable of producing synthetic biology tools, including genes, oligonucleotide pools and variant libraries. By synthesizing DNA on silicon instead of on traditional 96-well plastic plates, our platform overcomes the current inefficiencies of synthetic DNA production, and enables cost-effective, rapid, high-quality and high throughput synthetic gene production, which in turn, expedites the design, build and test cycle to enable personalized medicines, pharmaceuticals, sustainable chemical production, improved agriculture production, diagnostics and biodetection. We are also developing new technologies to address large scale data storage. For more information, please visit www.twistbioscience.com. Twist Bioscience is on Twitter. Sign up to follow our Twitter feed @TwistBioscience at https://twitter.com/TwistBioscience.

If you hadn’t read the EPFL press release first, it might have taken a minute to figure out why EPFL is being mentioned in the Twist Bioscience news release. Presumably someone was rushing to make a deadline. Ah well, I’ve seen and written worse.

I haven’t been able to find any video or audio recordings of the DNA-preserved performances but there is an informational video (originally published July 7, 2016) from Microsoft and the University of Washington describing the DNA-based technology,

I also found this description of listening to the DNA-preserved music in an Oct. 6, 2017 blog posting for the Canadian Broadcasting Corporation’s (CBC) Day 6 radio programme,

To listen to them, one must first suspend the DNA holding the songs in a solution. Next, one can use a DNA sequencer to read the letters of the bases forming the molecules. Then, algorithms can determine the digital code those letters form. From that code, comes the music.

It’s complicated but Ceze says his team performed this process without error.

You can find out more about UNESCO’s Memory of the World and its register here , more about the EPFL+ECAL Lab here, and more about Twist Bioscience here.

Historic and other buildings get protection from pollution?

This Sept. 15, 2017 news item on Nanowerk announces a new product for protecting buildings from pollution,

The organic pollution decomposing properties of titanium dioxide (TiO2 ) have been known for about half a century. However, practical applications have been few and hard to develop, but now a Greek paint producer claims to have found a solution

A Sept. 11, 2017 Youris (European Research Media Center) press release by Koen Mortelmans which originated the news item expands on the theme,

The photocatalytic properties of anatase, one of the three naturally occurring forms of titanium dioxide, were discovered in Japan in the late 1960s. Under the influence of the UV-radiation in sunlight, it can decompose organic pollutants such as bacteria, fungi and nicotine, and some inorganic materials into carbon dioxide. The catalytic effect is caused by the nanostructure of its crystals.

Applied outdoors, this affordable and widely available material could represent an efficient self-cleaning solution for buildings. This is due to the chemical reaction, which leaves a residue on building façades, a residue then washed away when it rains. Applying it to monuments in urban areas may save our cultural heritage, which is threatened by pollutants.

However, “photocatalytic paints and additives have long been a challenge for the coating industry, because the catalytic action affects the durability of resin binders and oxidizes the paint components,” explains Ioannis Arabatzis, founder and managing director of NanoPhos, based in the Greek town of Lavrio, in one of the countries home to some of the most important monuments of human history. The Greek company is testing a paint called Kirei, inspired by a Japanese word meaning both clean and beautiful.

According to Arabatzis, it’s an innovative product because it combines the self-cleaning action of photocatalytic nanoparticles and the reflective properties of cool wall paints. “When applied on exterior surfaces this paint can reflect more than 94% of the incident InfraRed radiation (IR), saving energy and reducing costs for heating and cooling”, he says. “The reflection values are enhanced by the self-cleaning ability. Compared to conventional paints, they remain unchanged for longer.”

The development of Kirei has been included in the European project BRESAER (BREakthrough Solutions for Adaptable Envelopes in building Refurbishment) which is studying a sustainable and adaptable “envelope system” to renovate buildings. The new paint was tested and subjected to quality controls following ISO standard procedures at the company’s own facilities and in other independent laboratories. “The lab results from testing in artificial, accelerated weathering conditions are reliable,” Arabatzis claims. “There was no sign of discolouration, chalking, cracking or any other paint defect during 2,000 hours of exposure to the simulated environmental conditions. We expect the coating’s service lifetime to be at least ten years.”

Many studies are being conducted to exploit the properties of titanium dioxide. Jan Duyzer, researcher at the Netherlands Organisation for Applied Scientific Research (TNO) in Utrecht, focused on depollution: “There is no doubt about the ability of anatase to decrease the levels of nitrogen oxides in the air. But in real situations, there are many differences in pollution, wind, light, and temperature. We were commissioned by the Dutch government specifically to find a way to take nitrogen oxides out of the air on roads and in traffic tunnels. We used anatase coated panels. Our results were disappointing, so the government decided to discontinue the research. Furthermore, we still don’t know what caused the difference between lab and life. Our best current hypothesis is that the total surface of the coated panels is very small compared to the large volumes of polluted air passing over them,” he tells youris.com.

Experimental deployment of titanium dioxide panels on an acoustic wall along a Dutch highway – Courtesy of Netherlands Organisation for Applied Scientific Research (TNO)

“In laboratory conditions the air is blown over the photocatalytic surface with a certain degree of turbulence. This results in the NOx-particles and the photocatalytic material coming into full contact with one another,” says engineer Anne Beeldens, visiting professor at KU Leuven, Belgium. Her experience with photocatalytic TiO2 is also limited to nitrogen dioxide (NOx) pollution.

In real applications, the air stream at the contact surface becomes laminar. This results in a lower velocity of the air at the surface and a lower depollution rate. Additionally, not all the air will be in contact with the photocatalytic surfaces. To ensure a good working application, the photocatalytic material needs to be positioned so that all the air is in contact with the surface and flows over it in a turbulent manner. This would allow as much of the NOx as possible to be in contact with photocatalytic material. In view of this, a good working application could lead to a reduction of 5 to 10 percent of NOx in the air, which is significant compared to other measures to reduce pollutants.”

The depollution capacity of TiO2 is undisputed, but most applications and tests have only involved specific kinds of substances. More research and measurements are required if we are to benefit more from the precious features of this material.

I think the most recent piece here on protecting buildings, i.e., the historic type, from pollution is an Oct. 21, 2014 posting: Heart of stone.

The science behind a hidden portrait by Edgar Degas

Rebecca Morelle’s Aug. 4, 2016 article for BBC (British Broadcasting Corporation) News online describes an intriguing piece of research into artists and how they work,

A hidden portrait by the French Impressionist painter Edgar Degas has been revealed by scientists.

Researchers in Australia used powerful X-rays to bring to light the painting of a young woman concealed beneath a work called Portrait of a Woman.

The researchers believe the subject is Emma Dobigny, who appeared in other Degas paintings.

Dr Daryl Howard, a co-author of the study, told BBC News: “I think what is really exciting is that we have now been able to add one more Degas artwork for the world to see.”

Edgar Degas, French, 1834–1917, Portrait of a Woman (Portrait de Femme), c. 1876–80, oil on canvas, 46.3 × 38.2 cm, National Gallery of Victoria, Melbourne, Felton Bequest, 1937. (a) Visible light image. The boxed region highlights the XRF scan area. (b) X-radiograph. The obscured portrait is rotated 180 degrees relative to the upper portrait. The face and ear of the obscured sitter are the primary source of contrast. (c) Reflected infrared image (detail). A partial outline of the obscured sitter’s face is indicated with a dotted line. The extensive use of highly infrared-absorbing black paint in the final composition provides a limited view of the underlying figure. Courtesy: National Gallery of Victoria, Australia

Edgar Degas, French, 1834–1917, Portrait of a Woman (Portrait de Femme), c. 1876–80, oil on canvas, 46.3 × 38.2 cm, National Gallery of Victoria, Melbourne, Felton Bequest, 1937. (a) Visible light image. The boxed region highlights the XRF scan area. (b) X-radiograph. The obscured portrait is rotated 180 degrees relative to the upper portrait. The face and ear of the obscured sitter are the primary source of contrast. (c) Reflected infrared image (detail). A partial outline of the obscured sitter’s face is indicated with a dotted line. The extensive use of highly infrared-absorbing black paint in the final composition provides a limited view of the underlying figure. Courtesy: National Gallery of Victoria, Australia

Morelle describes how the second portrait deteriorated such that a previous painting on the canvas was becoming perceptible and how scientists were able to ‘peel’ back the original to see what lay beneath,

It had long been known that Degas’ portrait of a woman wearing a black bonnet and dress, which he painted in the late 1870s, covered an earlier painting.

A ghostly impression of the composition appears as a dark stain on the sitter’s face, and over the years has become more prominent as the oil paint thinned.

Conventional X-rays revealed the outline of another image was lurking beneath, but without scraping away the outer painting, the researchers required a much more powerful technique to show any detail.

For that, they used the Australian Synchrotron, a huge accelerator that generates more powerful X-rays, to peer beneath the top layers of paint.

They were able to detect the metallic elements in the pigments that Degas had used in his underlying artwork.

Dr Howard, from the Australian Synchrotron, said: “Each element has its own unique signature, and so that gets collected.

“And what we do is analyse that data and build up these ‘elemental maps’. And that allows us to image all the different pigments used in the painting.”

Through this they were able to see in colour and in remarkable detail Degas’ hidden work: a portrait of a woman with auburn hair.

False colour reconstruction of Degas’ hidden portrait (detail). The image was created from the X-ray fluorescence microscopy elemental maps. (Edgar Degas, French, 1834–1917, Portrait of a Woman (Portrait de femme) c. 1876–80, oil on canvas, 46.3 × 38.2 cm, National Gallery of Victoria, Melbourne, Felton Bequest, 1937).

False colour reconstruction of Degas’ hidden portrait (detail). The image was created from the X-ray fluorescence microscopy elemental maps. (Edgar Degas, French, 1834–1917, Portrait of a Woman (Portrait de femme) c. 1876–80, oil on canvas, 46.3 × 38.2 cm, National Gallery of Victoria, Melbourne, Felton Bequest, 1937).

Apparently, Degas had a tendency, in his early paintings, to give his models pixie-like (longish and pointed) ears. Unusually, he has incorporated some of the features of the first painting into the second painting.

Getting back to the science, the technique used to ‘uncover’ the first painting is nondestructive (many techniques used in conservation are destructive as scrapings are required) and more powerful than previous x-ray techniques used to uncover artists’ secrets.

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

A Hidden Portrait by Edgar Degas by David Thurrowgood, David Paterson, Martin D. de Jonge, Robin Kirkham, Saul Thurrowgood, & Daryl L. Howard. Scientific Reports 6, Article number: 29594 (2016) doi:10.1038/srep29594 Published online: 04 August 2016

This paper is open access but for anyone who doesn’t have the time to read it, here’s a bit from the paper’s Discussion section (Note: Links have been removed),

We are not aware of any other current analytical technique that could have achieved such an imaging outcome for this painting. The data generated by this study has provided a better understanding of the artist’s technique. The 60 μm [micrometre] spatial resolution allows us to observe with confidence that a majority of the hidden sitter’s face has been achieved as one action. However the disproportionate and blurred form of the ears is indicative of several attempts to achieve the final proportions and features. Degas is reported as having painted “pixie” like ears at about this period46. By examining single elemental maps of the painting it is possible to observe such a “pixie” like ear shape (e.g., Mn and Fe, Fig. 3) which appears to have been reworked to a more conventional form (e.g., Co and Hg, Fig. 3). Careful study of the data reveals numerous intricacies of painting technique and brush stroke direction of the underpainting. It reveals stylistic information and elemental composition information that is unlikely to be reproducible by persons attempting to copy a work, and the technique has strong potential for application in authentication studies4,5.

Consideration has been given to the properties of synchrotron radiation, and the research group used visible and chemical observation to look for radiation-induced change in preliminary experiments. Pigment binder matrices were studied by Fourier Transform Infrared (FTIR) spectroscopy before and after extended X-ray exposure at the XFM beamline, and spectroscopic changes were not detected. No evidence for any chemical or physical change was observed for radiation doses 10,000 times that reported for this study, which is in accord with recent findings by other research groups using intense radiation sources47,48.

This study has successfully demonstrated a virtual reconstruction of a hidden portrait by Edgar Degas and has delivered a better understanding of his work and artistic practices. The authors propose that the unfolding technological developments for examining artwork using synchrotron radiation-based techniques will significantly impact the ways cultural heritage is studied for authentication, preservation and scholarly purposes. We anticipate that the high quality outcome presented here and the propagation of the rapid-scanning XRF detector technology used will further stimulate growing interest in the better understanding of our cultural assets. Parallel work using portable XRF systems7 is demonstrating that a version of the technique is becoming viable (at substantially reduced spatial resolution and increased data collection time) outside of a synchrotron facility, raising a strong likelihood that precedents being set at synchrotron facilities will directly influence emerging field-based technologies. Until recently XRF large area scanning facilities were built in-house, and this had limited the technique’s availability. With the introduction of commercial large scanning area instruments on the market49, the technique has the potential to expand rapidly.

And here’s just a bit from the paper’s Methods section (Note: Links have been removed),

The scanning XRF mapping of the painting Portrait of a Woman was performed at the X-ray fluorescence microscopy (XFM) beamline of the Australian Synchrotron31. The X-ray fluorescence was acquired with the Maia 384A detector array, which integrates the sample stage motion with continuous fly scanning, leading to zero data readout overhead50,51. An incident excitation beam energy of 12.6 keV was used to circumvent intense fluorescence from the Pb L absorption edges, which would originate primarily from the painting’s Pb-based ground layer and thereby limit detection sensitivity to other elements in the pictorial paint layers. The low-energy sensitivity of the detector is limited to approximately 4 keV, thus Pb-M fluorescence (~2.3 keV) was not detectable for example. The energy resolution of the detector is 375 eV at Mn Kα.

The artwork was fitted to a custom manufactured cradle for scanning. The painting was placed approximately 13 mm from Maia detector rather than the optimal distance of 10 mm, since the painting was not perfectly flat. The painting is shown mounted at the XFM beamline in Supplementary Material Fig. S1. A 426 × 267 mm2 area was raster-scanned at 16.4 mm s−1, providing a dwell time of approximately 3.7 ms per 60 × 60 μm2 pixel and yielded a 31.6 megapixel data set in 33 h. Given the 10 × 10 μm2 incident beam size used, the average time an area of the painting was in the beam was 0.6 ms. The average incident flux on the painting was 1.5 × 109 photons s−1.

For art historians, conservationists, scientists, and people like me (the curious), this is pretty exciting stuff.

I recommend reading Morelle’s piece for anyone who finds the science a little hard going as she does an excellent job of describing the science and the art.

YBC 7289: a 3,800-year-old mathematical text and 3D printing at Yale University

1,300 years before Pythagoras came up with the theorem associated with his name, a school kid in Babylon formed a disc out of clay and scratched out the theorem when the surface was drying.  According to an April 12, 2016 news item on phys.org the Bablyonians got to the theorem first, (Note: A link has been removed),

Thirty-eight hundred years ago, on the hot river plains of what is now southern Iraq, a Babylonian student did a bit of schoolwork that changed our understanding of ancient mathematics. The student scooped up a palm-sized clump of wet clay, formed a disc about the size and shape of a hamburger, and let it dry down a bit in the sun. On the surface of the moist clay the student drew a diagram that showed the people of the Old Babylonian Period (1,900–1,700 B.C.E.) fully understood the principles of the “Pythagorean Theorem” 1300 years before Greek geometer Pythagoras was born, and were also capable of calculating the square root of two to six decimal places.

Today, thanks to the Internet and new digital scanning methods being employed at Yale, this ancient geometry lesson continues to be used in modern classrooms around the world.

Just when you think it’s all about the theorem, the story which originated in an April 11, 2016 Yale University news release by Patrick Lynch takes a turn,

“This geometry tablet is one of the most-reproduced cultural objects that Yale owns — it’s published in mathematics textbooks the world over,” says Professor Benjamin Foster, curator of the Babylonian Collection, which includes the tablet. It’s also a popular teaching tool in Yale classes. “At the Babylonian Collection we have a very active teaching and learning function, and we regard education as one of the core parts of our mission,” says Foster. “We have graduate and undergraduate groups in our collection classroom every week.”

The tablet, formally known as YBC 7289, “Old Babylonian Period Mathematical Text,” came to Yale in 1909 as part of a much larger collection of cuneiform tablets assembled by J. Pierpont Morgan and donated to Yale. In the ancient Mideast cuneiform writing was created by using a sharp stylus pressed into the surface of a soft clay tablet to produce wedge-like impressions representing pictographic words and numbers. Morgan’s donation of tablets and other artifacts formed the nucleus of the Yale Babylonian Collection, which now incorporates 45,000 items from the ancient Mesopotamian kingdoms.

Discoverying [sic] the tablet’s mathematical significance

The importance of the geometry tablet was first recognized by science historians Otto Neugebauer and Abraham Sachs in their 1945 book “Mathematical Cuneiform Texts.”

“Ironically, mathematicians today are much more fascinated with the Babylonians’ ability to accurately calculate irrational numbers like the square root of two than they are with the geometry demonstrations,” notes associate Babylonian Collection curator Agnete Lassen.

“The Old Babylonian Period produced many tablets that show complex mathematics, but it also produced things you might not expect from a culture this old, such as grammars, dictionaries, and word lists,” says Lassen “One of the two main languages spoken in early Babylonia  was dying out, and people were careful to document and save what they could on cuneiform tablets. It’s ironic that almost 4,000 years ago people were thinking about cultural preservation, [emphasis mine] and actively preserving their learning for future generations.”.

This business about ancient peoples trying to preserve culture and learning for future generations suggests that the efforts in Palmyra, Syria (my April 6, 2016 post about 3D printing parts of Palmyra) are born of an age-old impulse. And then the story takes another turn and becomes a 3D printing story (from the Yale University news release),

Today, however, the tablet is a fragile lump of clay that would not survive routine handling in a classroom. In looking for alternatives that might bring the highlights of the Babylonian Collection to a wider audience, the collection’s curators partnered with Yale’s Institute for the Preservation of Cultural Heritage (IPCH) to bring the objects into the digital world.

Scanning at the IPCH

The IPCH Digitization Lab’s first step was to do reflectance transformation imaging (RTI) on each of fourteen Babylonian Collection objects. RTI is a photographic technique that enables a student or researcher to look at a subject with many different lighting angles. That’s particularly important for something like a cuneiform tablet, where there are complex 3D marks incised into the surface. With RTI you can freely manipulate the lighting, and see subtle surface variations that no ordinary photograph would reveal.

Chelsea Graham of the IPCH Digitization Lab and her colleague Yang Ying Yang of the Yale Computer Graphics Group then did laser scanning of the tablet to create a three-dimensional geometric model that can be freely rotated onscreen. The resulting 3D models can be combined with many other types of digital imaging to give researchers and students a virtual tablet onscreen, and the same data can be use to create a 3D printed facsimile that can be freely used in the classroom without risk to the delicate original.
3D printing digital materials

While virtual models on the computer screen have proved to be a valuable teaching and research resource, even the most accurate 3D model on a computer screen doesn’t convey the tactile  impact, and physicality of the real object. Yale’s Center for Engineering Innovation and Design has collaborated with the IPCH on a number of cultural heritage projects, and the center’s assistant director, Joseph Zinter, has used its 3D printing expertise on a wide range of engineering, basic science, and cultural heritage projects.

“Whether it’s a sculpture, a rare skull, or a microscopic neuron or molecule highly magnified, you can pick up a 3D printed model and hold it, and it’s a very different and important way to understand the data. Holding something in your hand is a distinctive learning experience,” notes Zinter.

Sharing cultural heritage projects in the digital world

Once a cultural artifact has entered the digital world there are practical problems with how to share the information with students and scholars. IPCH postdoctoral fellows Goze Akoglu and Eleni Kotoula are working with Yale computer science faculty member Holly Rushmeier to create an integrated collaborative software platform to support the research and sharing of cultural heritage artifacts like the Babylonian tablet.

“Right now cultural heritage professionals must juggle many kinds of software, running several types of specialized 2D and 3D media viewers as well as conventional word processing and graphics programs. Our vision is to create a single virtual environment that accommodates many kinds of media, as well as supporting communication and annotation within the project,” says Kotoula.

The wide sharing and disseminating of cultural artifacts is one advantage of digitizing objects, notes professor Rushmeier, “but the key thing about digital is the power to study large virtual collections. It’s not about scanning and modeling the individual object. When the scanned object becomes part of a large collection of digital data, then machine learning and search analysis tools can be run over the collection, allowing scholars to ask questions and make comparisons that aren’t possible by other means,” says Rushmeier.

Reflecting on the process that brings state-of-the-art digital tools to one of humanity’s oldest forms of writing, Graham said “It strikes me that this tablet has made a very long journey from classroom to classroom. People sometimes think the digital or 3D-printed models are just a novelty, or just for exhibitions, but you can engage and interact much more with the 3D printed object, or 3D model on the screen. I think the creators of this tablet would have appreciated the efforts to bring this fragile object back to the classroom.”

There is also a video highlighting the work,