TU Wien (Vienna) and its spin-off Cubicure have developed a new 3D printable, elephant-friendly ivory alternative called Digory.
Ever since the ivory trade was banned internationally in 1989, the world at large has been using substitute materials like bones, shells and plastic to restore ivory parts of old art objects. But this hasn’t always been a satisfactory solution and restored artifacts lack the precision and finish one would normally associate with ivory.
Now TU Wien and Cubicure have come up with a worthwhile substitute called Digory, developed in cooperation with the Archdiocese of Vienna’s Department for the Care of Art and Monuments and Addison Restoration.
Digory is composed of synthetic resin and calcium phosphate particles. It is processed in a hot, liquid state and hardened in the 3D printer with UV rays, exactly in the desired shape.
It can then be polished and color-matched to create a deceptively authentic-looking ivory substitute.
Shedding light on how the project began, professor Jürgen Stampfl said it all started with the evaluation of a valuable 17th-century state casket in the parish church of Mauerbach.
“It is decorated with small ivory ornaments, some of which have been lost over time,” says Stampfl. “The question was whether they could be replaced with 3D printing technology.”
According to Thaddäa Rath, who worked on the project as part of her dissertation, developing a suitable substitute for ivory was by no means an easy task.
They had to ensure that the material not only looked like ivory, but also see to it that it possessed the same strength and stiffness – apart from making the material machinable.
Through numerous experiments, Rath and her colleagues at TU Wien and Cubicure succeeded in finding the right mixture: Tiny calcium phosphate particles with an average diameter of about 7 µm were embedded in a special resin, together with extremely fine silicon oxide powder.
The mixture was then processed at high heat in Cubicure’s 3D printers using the hot lithography UV process.
“You also have to bear in mind that ivory is translucent,” notes Rath. “Only if you use the right amount of calcium phosphate will the material have the same translucent properties as ivory.”
The colour of the object can then be touched up with, in this case, black tea.
The characteristic dark lines that normally run through ivory can also be applied afterwards with high precision, says Rath.
The team is hoping that Digory will gain widespread acceptance as an aesthetically and mechanically high-quality ivory substitute, ensuring that no elephant ever loses a tusk again.
Image and content: TU Wien