3D printed material to replace ivory

PICTURE: Right: The new Digory material, left ivory More

Photo credit: Vienna University of Technology

For centuries, ivory was often used to make art objects. To protect the elephant populations, the ivory trade was banned internationally in 1989. In order to restore ivory parts of old art objects, substitute materials such as bones, shells or plastic must be used. So far, however, there has not been a really satisfactory solution.

The Technical University of Vienna (Vienna) and the 3D printing company Cubicure GmbH, founded as a spin-off from the Technical University of Vienna, have now developed a department for the care of art and monuments as well as the restoration of Addison in cooperation with the Archdiocese of Vienna: The new material “Digory” consists made of synthetic resin and calcium phosphate particles. It is processed in a hot, liquid state and cured in the 3D printer with UV rays in exactly the desired shape. It can then be polished and color matched to create a deceptively authentic looking ivory substitute.

Nice and mechanically stable

“The research project began with a valuable state box from the 17th century in the Mauerbach parish church,” says Prof. Jürgen Stampfl from the Institute for Materials Science and Technology at the Vienna University of Technology. “It’s decorated with small ivory ornaments, some of which have been lost over time. The question was whether they could be replaced by 3D printing technology.”

The team already had experience with similar materials: for example, the research group also works with ceramic materials for dental technology. Nevertheless, it was a challenging task to develop a suitable substitute for ivory: “We had to meet a whole range of requirements at the same time,” says Thaddäa Rath, who was working on the project as part of her dissertation. “Not only should the material look like ivory, it should also have the right strength and stiffness, and the material should be machinable.”

Stereolithography in a 3D printer

Through numerous experiments, Thaddäa Rath and other team members from TU Wien and Cubicure succeeded in finding the right mixture: Tiny calcium phosphate particles with an average diameter of approx. 7 μm were embedded in a special resin together with extremely fine silicon oxide powder. The mixture is then processed at high heat in Cubicure’s 3D printers using a hot lithography process: the material is cured layer by layer with a UV laser until the entire object is finished.

“You also have to remember that ivory is translucent,” explains Thaddäa Rath. “Only if you use the right amount of calcium phosphate will the material have the same translucent properties as ivory.” The color of the object can then be touched up – the team achieved good results with black tea. The characteristic dark lines that normally run through ivory can also be applied afterwards with great precision.

No more tusks!

This is a big step forward in the field of restoration: With the new material “Digory”, not only is a better, more beautiful and easier-to-use replacement for ivory available than before, but 3D technology also enables the finest details to be reproduced automatically . Instead of carefully carving them out of ivory substitute material, objects can now be printed in a matter of hours.

“With our specially developed 3D printing systems, we process different material formulations for completely different areas of application, but this project was also something new for us,” says Konstanze Seidler from Cubicure. “In any case, this is further proof of how diverse the possible applications of stereolithography are.”

The team hopes that the new material “Digory” will be generally accepted in the future – as an aesthetically and mechanically high-quality ivory substitute for which no elephant has to lose a tusk.



Prof. Prof. Jürgen Stampfl

Institute for Materials Science and Technology

TU Vienna

+43 1 58801 30862

[email protected]

Dipl.-Ing. Thaddea Rath

Institute for Materials Science and Technology

TU Vienna

+43 1 58801 30857

[email protected]

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