When the Francescuccio Ghissi’s St. John Altarpiece goes on exhibit September 10 at the North Carolina Museum of Art (NCMA), it will be the first time all nine panels have been exhibited in more than 100 years.

That’s because the ninth panel was missing until NCMA decided to mount the exhibit. Three panels, including the one shown here, are in NCMA’s collection. Three panels are in the Metropolitan Museum of Art, one in the Portland Art Museum, and the crucifixion panel is at the Art Institute of Chicago.

Ghissi’s Acteus and Eugenius Implore St. John the Evangelist to Restore Their Wealth
“Acteus and Eugenius Implore St. John the Evangelist to Restore Their Wealth”,
circa 1370–80, (Gift of the Samuel H. Kress Foundation)

The nine panels were dismantled and sawed apart in the late 19th and early 20th century and sold to art dealers and collectors.

Because the ninth panel was lost in the process, the NCMA decided to collaborate with Dutch conservation specialist Charlotte Caspers to re-create the missing panel using 14th-century materials and techniques. Working with NCMA’s David Steel and William Brown to determine the composition, coloring, and other details, Caspers created the panel with the same pigments and gilding used by Ghissi 650 years ago. Once completed, Duke University mathematicians developed algorithms to digitally age Casper’s work by matching crack patterns in the eight original panels.

Ghissi’s Acteus and Eugenius Implore St. John the Evangelist to Restore Their Wealth
The ninth panel showing “St. John the Evangelist Baptizing Aristodemus” is missing no longer.

“It was a true collaboration,” says Steel. “Everyone learned from each other’s research, and it resulted in this fascinating exhibition that combines art history, mathematics, and technology.”

Walking through the gallery, visitors will be able to travel from the 21st century back to the 14th century to see the reunited St. John Altarpiece as it originally appeared with the materials and techniques used by the artist to create it. The free exhibit is open through March 5.