POSTED BY Guest Blogger, ON April 04, 2012, 1 COMMENTS

If upon looking at the image below you are reminded of a pastry chef’s experiment gone wrong, think again. This is neither a layered cake nor a failed attempt at molecular gastronomy. And measuring less than 5 mm across, or roughly as big as a single sesame seed, it wouldn’t be very filling either.

What you see here is a paint cross-section: the result of going with a surgical scalpel at a painting. (If you are suddenly horrified at the mere mental association of scalpel and painting—like any true art-lover should be—know we do it in a very controlled and skilled way. In other words, please don’t try this at home!) Conservators and scientists typically sample at the edge of a painting or in unobtrusive areas, often by a pre-existing loss. We remove a microscopic fragment about the size of a grain of fine table salt and then embed the fragment in a clear resin. With some polishing, we’re able to expose all the painting layers that the artist applied in sequence on the canvas.

What you really see here though is a valuable piece of investigative evidence in the ongoing quest to understand a much debated work. It is a cross section from a painting (below) by El Greco entitled Saint Francis Kneeling in Meditation, 1595-1600. We are very fortunate at the Art Institute because this is one of several paintings on display at the museum by this great artist, who not only enjoyed public  recognition in his times, but also influenced some of the superstars of the modern and contemporary art world, including Pablo Picasso and Jeff Koons. And among Greco’s paintings at the Art Institute is the undisputed masterpiece of his early career, The Assumption of the Virgin.

Saint Francis, the founder of the Franciscan Order of friars, was a spiritual hero in late 16th century Spain. It has been estimated that nearly one fifth of the entire output of El Greco’s studio was represented by images of the saint. So if you go around the world and suddenly you think you have double vision because you could swear you have seen that same Francis pictured here, relax. You are not hallucinating. You are simply experiencing a clever production of multiples to satisfy an insatiable market.

How did El Greco do this?  What did he paint and what did he leave to an assistant?  One prominent 20th century scholar, Harold Wethey, thought he had all the answers in the 1960s based only on inspection of paintings and photographs. Citing “dull colors that lacked the brilliance of the master,“ the famous critic relegated our picture to art world purgatory: “workshop.”

But discerning between original work by the master, finishing touches to workshop productions, straight workshop versions, faithful copies, and outright forgeries sometimes takes more than the eye of the connoisseur. Nowadays the tools of science, in conjunction with conservation and art historical expertise, can help unravel some of these mysteries for good. In this case, our analysis disclosed pigments, a layer structure, and brushwork that are practically identical to the one unquestioned masterpiece of this subject: the St. Francis Venerating the Crucifix now in The Fine Arts Museums of San Francisco.

And so the sleuthing art detective found a trail of veritable fingerprints. We discovered bright, relatively expensive pigments (like azurite blue below and red lakes) in the priming layer, the layer that the artist applied as a basis for the painting itself. This points to the use of palette scrapings, or leftover bits of paint, a practice the young El Greco may have learned by the great masters Tintoretto and Titian during his training in Venice. On the other hand, a copyist would typically have imitated the warm color of the priming by using a much simplified and inexpensive mixture of pigments.

Moreover, X-radiography (a technique that uses x-rays to show the distribution of dense pigments and thus the artist’s changes) revealed subtle adjustments in the position of the head and hood of the saint. This is often considered a clear sign of the master rethinking his figure placement in paint, unlike what a pedantic assistant would do, preoccupied solely with producing an exact copy. Compositional changes (as revealed by comparing a visible image with an x-ray of the painting) likely denote an artist’s hand and not that of a copyist.

So in the end, art detective work—with scientists, conservators and art historians working together– provided convincing elements to the art historians to upgrade the judgment of the painting, assigning it to El Greco again. Call it a modern day redemption story: a comeback from art purgatory.

See the painting for yourself in our galleries, or come this Thursday, April 5th, at 6 pm in Fullerton Auditorium at the Art Institute, to hear the whole story during Copies as Originals—Decoding El Greco’s Studio Practice.

—Francesca C., Andrew W. Mellon Senior Conservation Scientist

Image Credits: El Greco (Domenikos Theotokopoulos), Saint Francis Kneeling in Meditation, 1595–1600. The Art Institute of Chicago, Robert A. Waller Memorial Fund.

http://www.mines.unr.edu/museum/minerals/Azurite.htm

Contour line overlays by Kuniej Berry Associates, LLC

POSTED BY Guest Blogger, ON March 09, 2012, Comments Off

In the latest Woody Allen movie Midnight in Paris the protagonist, played by Owen Wilson, is writing a book on nostalgia. Similarly, the man I was with in Paris’s Tuileries gardens some days ago was also most definitely trafficking in nostalgia. Charmingly scruffy and with fingers still encrusted with remnants of his work, he is a restorer I met during his lunch break. He was working on the conservation of a 17th c. Venetian ceiling in the Louvre – complete with gilded plaster, frescoed putti, and all the splendor of a bygone era.

Halfway through our lunch he went rummaging into his well-worn leather sack, a mischievous grin on his lips. To my delight, he extracted a bag full of five or six small and oddly shaped bottles containing amber colored, resinous liquids at various stages of solidification. My eyes went quickly scanning for those oh-so familiar elements… the pungent smell of solvent, the encrusted caps…all signs confirming that the content was old!

Siccatif de Harlem, the resinous liquid in those bottles, is an artist’s material based on hard copal varnishes. Secreted by the trees of Trachylobium species in Africa, Hymenaea courbaril in South America, and Agathis australis in New Zealand, copals are also obtained as fossil resins from Zaire and Zanzibar. This hard resin cannot simply be diluted in oil or thinned with solvents; it needs to be boiled for a long time and thus melted at high temperature. When mixed with traditional fine artist’s oil paint from a tube this material can accelerate its drying (from several months to a few days!) and dramatically alters the paint’s look and flow. Research conservators here at the Art Institute recently put on the sorcerer’s hat and made replicas of what results an artist may obtain in his studio with this siccatif: see for yourself how the viscous consistency of oil paint is transformed into a glossy, flat, almost enamel-like surface.

Here’s an image of the typical, viscous consistency of oil paint from an artist’s tube:

And here’s an image from the same tube of paint, but after the addition of Siccatif de Harlem:

In many ways science is like love: sometimes it is hard to find a match if you don’t know what you are looking for. And the siccatif you can buy today has often nothing more in common with the original turn of the century product than a name on its label, just like those photos people post on dating websites, picturing a 10-year younger version of themselves.

But now, with these bottles of Siccatif de Harlem in my suitcase I felt like a true art-detective, collecting fingerprints of likely candidates to compare with my mystery paints. The unknown paint is a minuscule fragment of a painting from the Art Institute of Chicago’s Still Life, 1922, by Pablo Picasso, nearly invisible to the naked eye. Painstakingly going through the online archives of the Picasso Museum in Paris we found another clue—a receipt proving that Picasso did indeed buy Siccatif de Harlem.

I can feel the excitement as the pieces of the puzzle are coming together. And so the quest begins. After unpacking my suitcase I’ll analyze the resinous material from the small bottles. Keep your fingers crossed that it is a match.

—Francesca C., Andrew W. Mellon Senior Conservation Scientist

POSTED BY Guest Blogger, ON October 04, 2011, 3 COMMENTS

The other day when we asked “Where’s the Caillebotte?,” we explained that it was being x-rayed in the conservation lab and invited visitors to strike a pose with the frame—an invitation that was taken up by a few of our art handlers. But really, the extent of what was done in our lab was more complicated than that, so I thought I would expand on the process.

The first step was taking an x-ray, which requires a special set-up for such a large painting. Here in the lab the painting was placed face-up on long beams to hold it above the x-ray unit. It was measured and a grid of thin thread was pinned to the edges to help line up the sheets of film and avoid any gaps. The x-ray unit itself is inside a lead-lined box on wheels with a rectangular opening facing the painting. It allows the x-ray beam through the painting to expose the film, in a light-protective sheet on top. The small beige booth behind the painting at the center of this picture is where I manned the controls.

This little booth is leaded, as well as the glass, to protect the operator while the x-ray unit was energized (as indicated by the red light below). For each capture, a new x-ray film and protective sheet was placed on the grid, and the x-ray unit was rolled underneath to correspond with that space.

Here’s the view from where I stand during the process:

Each sheet of film was developed and placed on the big wall-sized light box in our examination room. Once we did some test shots to figure out our exposure settings, we developed the film in batches. Putting the film up like this is a bit like a puzzle, but it helped us see the overall picture and make sure we haven’t skipped anything. The grid we made also takes into account a certain amount of overlap between the films—seen here on the light box—which will help us when we scan and digitally composite them.

We also took the opportunity to take some infrared images of the painting in both reflected and transmitted light. In the infrared part of the light spectrum, the longer wavelengths penetrate the upper paint layers and we have the ability to see changes in the paint not visible on the surface, as well as some kinds of underdrawing. The camera is tethered to the computer so I can see the images as they are generated. Along with the x-ray, these images give us a better picture of Caillebotte’s working process.

Finally when our work is done, the installers placed the painting back in its frame on the gallery wall for your continued viewing pleasure. Stay tuned for the results of our technical imaging in conjunction with the Impressionism, Fashion, and Modernity exhibition.

—Kelly K., Andrew W. Mellon Fellow, Paintings Conservation

POSTED BY Katie R., ON September 28, 2011, 1 COMMENTS

Where’s the Caillebotte? It’s a common question around the museum today, both because Paris Street; Rainy Day is among the most beloved works in the museum’s collection and because it is quite obvious that something is missing in Gallery 201. The truth of the matter is that the Caillebotte will be off-view for just a few days—it’s currently in our conservation studios being x-rayed for research purposes before it begins its extended run in the upcoming exhibition Impressionism, Fashion, and Modernity.

It will be back late on Friday, but before then, its absence presents a great chance for a photo op!

POSTED BY Guest Blogger, ON August 01, 2011, Comments Off

If I say “ring” you might first think of Frodo. Or maybe Wagner if you’re an opera lover. But you’ll find neither Hobbits nor Valkyries at the ring-shaped Argonne National Laboratory just outside Chicago. What you will find is Art Institute conservation scientists, as we visited the Lab this month on a mission to bring Picasso to the ring.

Let me qualify that: we brought minuscule samples of Picasso paintings from the Art Institute to the Advanced Photon Source, the Western hemisphere’s brightest source of X-ray beams. At this top-notch facility, scientists rip electrons from atoms and make them spin furiously around the circumference of the experiment hall—which is large enough to encircle a baseball stadium. These enraged electrons (always charged with that negative attitude!) give off enormous amounts of energy, which the scientists can bend and direct to do wonderful things.

We used the energy from this process to penetrate every single grain of white pigment that Picasso used with nanometric resolution (that is, splitting human hair eighty thousand times to get down to a nanometer) in order to determine where it came from. Was it from a wrinkled tube from one of the artist’s storied houses, produced on the banks of the river Seine in chi-chi Paris? Or did it come from a drippy can of mass-market produced house paint? Could the paint possibly have been made in the U.S.? By looking at infinitesimal contaminants in these zinc oxide pigment particles we hope we will be able to answer these questions and advance our Picasso-related detective work.

Often conservators are surprised to find themselves in facilities such as these. But at Argonne, scientists riding around on tricycles (the facility’s favored mode of transportation) were probably just as surprised to find us. These scientists were encountering Picasso in unexpected places: posted in a note with our project title on our experimental station’s door and attached with a drop of nail polish (an ironic fate for a known womanizer!) on a small pin!

Outside, at night (yes, because when you are awarded time for an experiment, you work 24/7 for 5 days: science cannot wait), dragonflies sparkle amidst the grass in the calm, bucolic setting. Inside, it sparkles too…we are brimming with the excitement of discovery. And that is how Picasso, a trailblazer in both life and death, went nanotech at Argonne on a hot day in July 2011.

—Francesca C., Andrew W. Mellon Senior Conservation Scientist

Image Captions:

Top image: The Advanced Photon source inside and out: the “ring” at Argonne National Laboratory (left) and one of the tricycles used to circulate around the 2/3 of a mile circumference (right)

Bottom image: Beamline scientist Volker Rose inside the control room. At right, tools of the trade, and our Picasso sample (try to spot the almost invisible white paint chip hanging in the circular hole!)