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Art Scene Investigation: Testing the DNA of Sculptures

POSTED BY , ON May 10, 2013, Comments Off

Most of the time when I read about science and art in the newspaper, the story involves forensics and fakes. Now, I hold no grudges to CSI (after all, they’re the ones who made science look riveting), but analyzing art is so much more than fake-busting.

For example, one thing we are always very interested in here at the museum is where things come from, or “provenance” in art-speak. Frequently, the museum’s records can easily show the path of ownership from the artist to the museum. But when that path is not so clear, curators determine provenance by combing through papers and archives: letters, diaries, photos, newspaper clips, exhibition reviews, catalogues, contracts etc. Nothing escapes their peering eyes. But in situations when archives might not hold the answer, we look to science.

The bronze sculpture Head of a Woman (Fernande) (image below left)—which you can find surrounded by arresting works on paper in one of the galleries of Picasso and Chicago—has a rock-solid provenance. It was once part of the collection of Alfred Stieglitz, the famous pioneer of all things photography and champion of avant-garde art. He bought it directly from Ambroise Vollard, to whom Picasso had sold the plaster version and rights to cast.

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But unlike Fernande, Jester (image above right) has a more fragmented paper trail. So where are these sculptures really from? Where were they made?

If you look closely at bronze sculptures of the period (But not too close! Or a guard may rightly offer a reprimand. Nobody wants nose-prints on their collection…) you will notice foundry marks like the ones below.

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A bit like cowboys do with cattle in fact, the different Parisian foundries would imprint their names on the sculptures they cast. But not all the time. To complicate the situation further, unlike today when an artist may issue a limited numbered edition  of his or her work, in the early 1900s dealers like Vollard would have a bronze cast made only when they had a definite client for it. And we don’t have good records of all these different casts for Picasso. Also, to complicate things even further, you have to take in account when the casting occurred. Sculptures that are cast later are less valuable than very early editions.

So what does the art detective do? Interrogate the sculptures themselves!

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We first took a look at the materials and specifically the composition of bronze or brass. (Bronze is made primarily of copper, tin, and lead and brass is made of copper, zinc, and lead.) We used a portable elemental analyzer (or x-ray fluorescence (XRF) spectrometer ) to test the type and amount of these components on all the  sculptures (68 total) we could get our hands on that were cast in Paris at the beginning of the 20th century. The good news is that, just like your aunt’s favorite brownie recipe, which she would not give away even if you bribed her, foundries had their secret mixtures that allowed the molten metal to flow better, produced fewer casting flaws, reduced the filing work after the cast, took up the patina better, etc.

This is good for us, because then the composition of the metal becomes the sculpture’s DNA that we can trace all the way down to the original foundry. And so we were able to rejoin Jester with his family of bronzes, some of which had a foundry mark of the firm Bingen and Constenoble (whose foundry mark is pictured below).

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Flowers in a Vase, also in the exhibition, grouped very well with the lost wax casts of the Valsuani foundry, one that produced many other works by Picasso. And Fernande? She proudly remains isolated, with a unique alloy of which, to this very day, we have found no equals. Only more analysis on more sculptures will help us nail down the foundry that made it. In the meantime I am pleased that with the help of science we have finally rejoined the Jester with its own makers.

Believe it or not, the whole story is told in the graph below. Now, after a tale of molten metal sparks, industrial secrets, and the mystery of the missing stamps, who can say science is boring?

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—Francesca Casadio, Andrew W. Mellon Senior Conservation Scientist

Image Credits:

Pablo Picasso. Head of a Woman (Fernande), 1909. The Art Institute of Chicago, Alfred Stieglitz Collection. © 2013 Estate of Pablo Picasso / Artists Rights Society (ARS), New York.

Pablo Picasso. Jester, 1905. The Art Institute of Chicago, Kate L. Brewster Collection. © 2013 Estate of Pablo Picasso / Artists Rights Society (ARS), New York.

 

Conservation Station

POSTED BY , ON November 09, 2012, 1 COMMENTS

When the new Mary and Michael Jaharis Galleries of Greek, Roman, and Byzantine Art open to the public this Sunday, November 11th, visitors will have the opportunity to examine never before seen pieces alongside favorites from the collection. But even if you’ve seen some of these artworks before, they’ll look better than ever thanks to work recently done by the museum’s conservation team.

A special education section of the gallery will now feature a display that explains the conservation process for some of these works. This area will include a video detailing the different techniques used, as well as the process of conserving ancient art. In anticipation of the opening, check out these behind the scenes photos of Art Institute staffers and a visiting conservator restoring and cleaning some of the objects in the new galleries.

—Chris Audain, Assistant to the Chair, Department of Ancient and Byzantine Art

Art Scene Investigation: Copies as Originals, or a Strange Case of Double Vision

POSTED BY , 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

Art Scene Investigation: The Art Detective Goes to Paris

POSTED BY , 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

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So Where Exactly Was the Caillebotte?

POSTED BY , 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

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