Hi-tech reveals ‘hidden doors’ in ancient artifacts, paintings

‘The idea is that you use technology to find information that cannot be seen by the naked eye,’ says expert at Jerusalem conference.

By DANIEL K. EISENBUD
Updated: DECEMBER 12, 2016 23:36
A screenshot of an oil painting next to its x-ray image showing hidden elements. (photo credit: DANIEL K. EISENBUD)
A screenshot of an oil painting next to its x-ray image showing hidden elements.
(photo credit: DANIEL K. EISENBUD)
Behind every great painting, and inside every rare relic, are “hidden doors” that state-of-the-art non-invasive X-rays can now open, revealing pathways of information without laying a finger on valuable and fragile antiquities.
Fifty world-renowned experts in the fields of advanced imaging shed light on how researchers identify chemical compositions and hidden layers in paintings and ancient vestiges at the commencement of the three-day Second International Conference on Art and Archeology in Jerusalem on Monday.
Dr. Amos Notea, professor emeritus at Technion-Israel Institute of Technology and chairman of the master’s program in Quality Engineering at the Holon Institute of Technology, is a leading figure in “nondestructive testing” and will be lecturing at the conference.
“This is our second conference since 2008, and it is dedicated to advanced measurements in archeology and art,” Notea said outside a lecture hall at the Crown Plaza. “The idea is that you use technology to find information that cannot be seen by the naked eye.”
“You find hidden doors,” he added.
Notea said the term “hidden doors” was coined in archeology after researchers used infrared scanning, radar and ultrasonic measurements to discover concealed chambers behind walls in the tomb of the Egyptian pharaoh Tutankhamen.
Experts in engineering, physics and chemistry have gone on to use similar noninvasive technology to reveal previously unknown elements within a plethora of historic paintings and antiquities.
“X-ray fluorescence shoots a beam of invisible radiation at an object to detect electromagnetic radiation, which reveals the elemental composition inside it,” Notea said.
“So, you can take an ancient ceramic jar and find inside trace elements of iron and zinc without touching it.”
The same technology is used on the canvases of historic paintings to reveal hidden layers of art behind what appears to be the final product.

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Noting that ancient canvas for oil painting was prohibitive in price, Kfir Kirshner, a nondestructive testing expert at Logos Imaging, said portable X-ray digital and computerized radiography technology is used to reveal previous iterations behind visible art.
“The costs of canvas in the old times was very expensive, so if an artist could not sell his painting, he would just paint over it and start again,” said Kirshner. “So, sometimes the paintings beneath the paintings are more valuable.”
To reveal such hidden layers, Kirshner displayed a computer image of an oil painting from the Vatican next to its X-ray image.
“You can see the face of the man in the X-ray version was once blindfolded, so maybe what happened was the artist said, ‘I now don’t want him to be blindfolded,’ so he just painted over it,” he said.
“I’ve seen several paintings that have completely different paintings beneath them.
You can use the same technology in excavation, which is frequently used to see what is inside mummies. It’s very similar to medical technology, except the sensors are designed to work in harsher environments.”
All the necessary equipment, Kirshner illustrated, can be contained in a midsized pelican case.
“In several Van Gogh paintings I have studied, you can see multiple layers of other paintings,” he said.
Notea said the technology can readily be applied to identify forgeries by dating the canvas and paint used.
“The canvas and paint in every period have different elemental compositions, so it’s not easy to forge an original work unless you have the original canvas and paints,” he said. “When you study paintings from 100 years ago, you find a lot of lead, chrome, copper, zinc and so on. But today, the departments of health in all countries do not allow you to use lead, because it is poison.”
Presentations during the conference will include: “3D-Scanning as a New Tool in the Research of Architectural Decoration”; “Noninvasive Analysis of the Wall-Paintings from the Domus Dei Bucrani (60 BCE) in Ostia”; “Conservator’s Examination in Brick Barracks on the Premises of the Former Auschwitz–Birkenau Concentration Camp – Project Presentation”; and “Four Hundred Meters Below Sea Level; Micromorphological, Chemical and Physical Characterization of Waterlogged Archaeological Wood Finds from the Dead Sea Shore.”
Dr. Henry Horwitz, co-managing director of ISAS International Seminars, which arranged the conference, said some 130 people will attend nearly two dozen lectures from international luminaries on various uses of nondestructive technology.