Magnified Views of Metal Look Like Mesmerizing Micro-Landscapes

Look closely: The story of an object’s making is hidden in plain sight.

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Apr 4 2017, 2:36pm

Conservators look through microscopes to gather information about an object's composition and construction—and on a regular day in the lab, knowing such things is an end unto itself. "It's just interesting, that's all," one conservator once told me. When an object's history is uncertain, however, those scientific results take on layers of meaning, each a potential bit of evidence that can help solve the mystery. In 2001, conservators at the J. Paul Getty Museum undertook a thorough reexamination of a massive French cabinet long believed to be a fake: a 19th century piece designed to resemble Renaissance-era handiwork. Zooming in on a single brass tack turned out to yield important clues as to the cabinet's making, and helped prove its authenticity.

When J. Paul Getty purchased the cabinet in 1971 for $1,700, curators warned against the acquisition. The cabinet's pristine condition aroused suspicions, as did the coating of colored wax on its surface, which suggested someone had tried to make it appear older than it was. Experts concluded that the piece was likely produced in the 19th century, when Renaissance-style furniture was all the rage among American industrialist tycoons—prompting many fakes to voyage across the Atlantic. Even the cabinet's excessively florid style worked against it: "A present-day tendency to associate heavy forms, sharp carving and dense decorative detail with neo-Renaissance cabinetry perhaps explains why further suspicions arose. The decoration almost suggests 19th century horror vacui," noted curator Jack Hinton and conservator Arlen Heginbotham in a 2006 article about the object.

French Renaissance Cabinet from Burgundy, dated 1580 (minor additions in late 1850s), from the J. Paul Getty Museum collection

Heginbotham looked past all that noisy decoration and zeroed in on the science. Dendrochronology, or tree-ring dating, showed that the oak tree used in the object's construction was harvested in the mid-1570s, and the surface wood and interior silk lining were carbon dated to the 15th and 16th centuries. Conservators then focused on the brass tacks used to attach the silk lining, whose appearance under the microscope—centuries later—would determine the date of their making.

View of silk lining and tacks inside the cabinet

Conveniently, one of the tacks had come loose and made for a perfect candidate for analysis: It was lodged in resin, sliced, polished, etched, and placed under the microscope, revealing crystalline patterns (above) that indicated the metal was cast by hand, not hammered or stamped as it would have been in the 1800s. "19th century industrialization led to far more mechanization of small manufactured objects like tacks, and machines for converting wire stock into tacks became much more common," explains Heginbotham in an email to Creators.

"The structure of the cast metal is called dendritic (tree-like). This is the crystal structure that forms naturally as the metal cools slowly," he adds. In contrast, hammered brass of a similar composition would have shown a network of strain lines and angular edges—like the example below.

Brass specimen of a similar composition to that of the tacks in the Renaissance cabinet, but hammered

Further evidence supported a rewriting of the object's history. The back of the cabinet bore the markings of 16th century woodworking tools, and archival documents pointed to the likely original owner, a French nobleman whose furniture collection was inventoried after his death in 1596. By 2005, the Getty had enough confidence in the cabinet's authenticity to put it on display with a new dating of 1580—finally taking those numbers, which are painted on one of its wooden panels, at face value.

You can learn more about the Getty's discovery here, and watch a video of the sampling of the tack here—but if you want to take a deeper dive into the mesmerizing visuals of metallography, scroll on. David Scott, UCLA professor and author of Metallography and Microstructure of Ancient and Historic Metals, has amassed the world's best collection of mounted metallographic specimens. Here are but a few examples from his vast collection, as seen through a microscope:

Anglo-Saxon blade, 7th to 10th century AD. Via Instagram, with permission

Pure copper electrotype tea caddy, 1880-89, from the Victoria and Albert Museum. Via Instagram, with permission

Specimen from a Bronze Age palstave from Kent. Via Instagram, with permission

Wootz steel (cast crucible steel) from Deccan, India. Via Instagram, with permission

For more, follow David Scott on Instagram at @davidscottmetals.

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