UNT engineer's research looks beyond paint, metals and ceramics

Monday, April 11, 2016 - 15:07

A UNT materials scientist is investigating a secret underneath the final layer of paint on Alessandro Allori's Portrait of Grand Duchess Bianca Capello de Medici with Her Son. The portrait, which was painted more than 500 years ago, is one piece of a story about a controversial royal family. The painting currently is being treated and studied by Paintings Conservation Fellow Laura Hartman in the Dallas Museum of Art's visible conservation studio.

Marcus Young, assistant professor in UNT's Department of Materials Science and Engineering, is leading a project where he and students in UNT's College of Engineering use advanced materials characterization research equipment to look underneath the portrait's final layer. He also is exploring how 3D printing technologies can create reproductions of famous sculptures and is using a scanning electron microscope with a focused ion beam to learn how silver-plated metal objects in the museum's collection were created and can be conserved.

"Working with UNT engineers has been great because they've been able to bring their background into this project and come up with really interesting imaging and analysis techniques," Hartman said.

3D Printing, Metals

While much is known about the history of American silver and silver-plated objects in the Dallas Museum of Art's metals collection, which is one of the world's largest, information about the materials processing and manufacturing of many the objects is not well-known.

Young and his students are using a dual beam ultra-high resolution field emission scanning electron microscope with a focused ion beam in UNT's Center for Advanced Research and Technology to create a window – a 30×30×30 micron window, smaller than the width of a human hair – to look inside each object and learn about its processing history.

"Using this equipment we can determine what processing and manufacturing techniques the artist used to build the object, what base metals were used and even get details on grain size and plating," Young said. "The ion beam creates such a small hole that no one will ever know that we touched anything."

3D printing technology has advanced to the point that Young can now print near exact replicas of some of the museum's ceramic objects, which allows staff to be able to transport and display replicas without fear of damaging the original.

"You could build an exact replica of a ceramic object by hand, but with our equipment we get the exact dimensions and are able to print them nearly perfectly," Young said. "We're able to capture all the characteristics and flaws of the original, and staff from the museum can transport and display the replica without having to worry about damaging an irreplaceable art object."

Bianca Capello de Medici

Bianca was born in Venice in 1548. She eloped at 16 years old and moved to Florence with her husband, where she later fell in love with Grand Duke of Tuscany Francesco I de' Medici. Francesco, at the time, was married to Joanna of Austria, daughter of Holy Roman Emperor Ferdinand I.

The Medicis were well-known patrons of Renaissance art, and were famous for their large collection of family portraits, Hartman said. 

Bianca's husband was murdered in 1572, and Joanna died a few years later, opening the door for a romance between Bianca and Francesco that spurred a lot of questions and conflict.

"The portrait is of Bianca and her son with Francesco, his name was Antonio," Hartman said. "Antonio's story is interesting because there are questions about the legitimacy of his birth – was he born before or after his parents were officially married? Was he a changeling? All of the questions and rumors circled around his right to the throne and the title Grand Duke of Tuscany."

Bianca and Francesco died on the same day in 1587 from an unknown illness. Their deaths brought more intrigue and more unrest. 

"People asked if they were poisoned or if they were murdered," Hartman said. "After their deaths, Francesco's brother Ferdinando made a call to destroy all memory of Bianca – all images of her and her coat of arms. So, the fact that this painting survived is incredible."

Art conservators and historians who have looked at the painting notice something interesting about Antonio's face. His face appears to have been repainted at some point over an earlier younger face, but no one knows exactly when or by whom the alterations occurred. Young is using advanced materials equipment to find answers.

"It's of historical interest since the family used the painting to legitimize their son, the heir. What we believe is underneath is a younger version of their child, Antonio, which was later repainted," Young said.

Young and Hartman are using a combination of X-ray imaging, X-ray fluorescence spectroscopy and scanning electron microscopy as well as synchrotron radiation X-ray fluorescence spectroscopy available at the Advanced Photon Source at Argonne National Laboratory to create a detailed map of the underlying colors and shapes. He also is working to identify chemical differences in the paints used in the top and underlying layers, which will be used to reveal and reconstruct the underlying image of the child.

"There is so much to learn about history through this type of research and collaboration," Hartman said. "Bianca's story is such a tangled web, and we're looking forward to finding out what we can learn about the age of the paint and the portrait beneath."

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