Conservation Now

Replacing missing fingers and toes with 3D printing technology

Objects Conservator Paula Artal-Isbrand

Over the past two years, Objects Conservator Paula Artal-Isbrand has gone through the painstaking process of cleaning the 19th-century sculpture, Shipwrecked Mother and Child, by Edward Augustus Brackett. Acquired by the Museum in 1904, the sculpture was stored in the basement for 80 years until it was moved to the Jeppson Idea Lab for conservation in December 2019. Visitors have been able to watch as the marble statue, dirty and dingy from decades of exposure to pollution and grime, gradually took on its original brilliant white color. In early 2020 Artal-Isbrand began a partnership with scientists at Worcester Polytechnic Institute (WPI) to prepare for the second conservation treatment phase: replacing toes and fingers that were damaged or lost over the years. For this complex process, Artal-Isbrand worked with graduate student Colin Hiscox and undergraduate student Nathan Kaplan under the supervision of Professor Cosme Furlong-Vazquez, Director of the Laser Holography Lab in the Mechanical Engineering Department. Because the sculpture is a representation of human figures, which are by nature symmetrical, the project lent itself perfectly to 3D technology for the restoration of missing digits. For most of the losses, primarily fingers and toes, their mirror-image counterparts on the other side of the bodies were fortunately undamaged and thus served as prototypes for the restorations. The existing fingers and toes were scanned with a high resolution, Academia 50 3D Digitizer from Creaform that WPI acquired for this project. Then, computer-generated algorithms turned the scanned information into a digital model which was mirrored to produce the desired shape and size of the missing fingers and toes. These files were ultimately 3D printed by Professor Erica Stults, director of WPI’s Advanced Prototyping Lab.

According to Artal-Isbrand and Hiscox, the next phase of the project—fitting the printed prototypes to the sculpture—was the most challenging and time consuming, with Hiscox making numerous trips to the Museum. Because the printed parts did not always perfectly match the surface contours at the break site, the parts needed to be rescaled and reshaped to be consistent with the rest of the sculpture. The challenge did not just involve fitting the pieces seamlessly onto the surface of the sculpture, but also ensuring that the directionality of the replacement digit looked anatomically

Academia 50, 3D Digitizer

Two 3D printed digits

Worcester Polytechnic Institute Professor Cosme Furlong-Vazquez with graduate student Colin Hiscox Left foot of mother before and after restoration

“It was a conversation between Colin and myself, a collaboration of two minds: a conservator and a mathematician, engineer, and scientist. Our ultimate goal was to have Brackett's approval!”

correct. It took several sessions of scanning and at least 10 rounds of subsequent printing of prototypes until Artal-Isbrand and Hiscox were satisfied.

“It was important to integrate the 3D-printed restorations into the sculpture so they would sit in a natural manner consistent with human anatomy,” explained ArtalIsbrand. “It was a conversation between Colin and myself, a collaboration of two minds: a conservator and a mathematician, engineer, and scientist. Our ultimate goal was to have Brackett’s approval!”

“The biggest reward was seeing the computer-generated parts fit onto the statue. When they fit nicely and smoothly, it was very satisfying,” says Hiscox.

The final iterations were printed on an Objet260 Connex printer using an acrylicbased resin, chosen very carefully for this conservation project.

“As art conservators we carefully select the materials used in our restorations. We make sure they fulfill certain requirements, including that they are inert, do not change color and consistency over time, are different than the original, and are fully reversible at any time in the future,” Artal-Isbrand says.

Finishing the new digits involved coating them with a conservation-grade acrylic primer and then painting them with conservation-grade acrylic paints and varnishes to match the color of the marble. Artal-Isbrand adhered archival paper to the base of each 3D-printed restoration to serve as a barrier between restoration and original materials, and also to facilitate reversal of the adhesive join should that be needed in the future. She then attached each 3D restoration with an acrylic adhesive. Once in place, the final retouching with the acrylic paints fully integrated the restorations into the artwork so that even Brackett wouldn’t know they were not original.

But why restore the missing parts of this artwork? Artal-Isbrand says, “Shipwrecked Mother and Child is overall pristine, the missing parts were small, and it was clear what they were. By restoring them, we thereby averted a potential visual distraction. This will give our visitors a rich viewing experience, and allow them to fully enjoy this impeccable masterpiece by Edward Augustus Brackett.”

This project has been generously supported by the Henry Luce Foundation.