3D digitization meets ultrasound
For instance, the experts expanded the CultLab3D approach to include an ultrasound analysis. “In other words, in the digital representation, the restorers can zoom in to the object’s interior, enabling them to see immediately whether there are any hidden instabilities, corrosion or holes,” says Peter-Karl Weber, a group manager at the Fraunhofer Institute for Biomedical Engineering IBMT. What’s more, these analyses can now be completed in just a few seconds.
This is made possible by an elastic belt fastened to the object. “An ultrasonic transducer is attached to each belt. Special electronics enable these transducers to switch between transmitter and receiver. Now, instead of having to constantly reposition the ultrasonic transducer, one needs only place the belt on the work of art. Thanks to QR codes on the transducers, a camera can identify the position at which the ultrasound tomogram was recorded, and software inserts the ultrasound images into the digital scan.
For ultrasound examinations, doctors apply a gel to patients’ skin to transmit the ultrasonic waves into the body, but this gel would damage works of art. Researchers at the Fraunhofer Institute for Applied Polymer Research IAP are therefore developing a material that enables dry-coupled ultrasonic testing. This material has the same properties as the gel and can be removed without leaving any residue.
Enameled gold in the Green Vault
The Green Vault in the Dresden Castle is one of the most famous museums in Saxony. It also houses court jeweler Dinglinger’s filigree enameled gold treasures depicting the court of India’s Great Mogul.
For decades, the pieces were exhibited in showcases that, unbeknownst to the museum, were off-gassing many harmful substances. As a result, the intricate en-ameling gradually began to peel off. The fragments were meticulously collected, but how would restorers be able to reattach them? Any suitable conservation material must meet some extremely strict requirements: it has to be transparent, highly durable and have similar properties as glass, and it must also firmly bond enamel and metal.
“We developed a suitable material for this at the Fraunhofer Institute for Silicate Research ISC in Würzburg twenty years ago: enamel ORMOCER® ,” explains Dr. Gerhard Schottner, who heads the department for glass research there. Besides its suitability for lasting conservation of enameled treasures, it can also permanently bond ivory and rock crystal, as was discovered in the restoration laboratory at the Dresden State Art Collections. Unfortunately, over the years, the raw materials supplied by industry sources became unavailable in the required quality, and even the slightest impurities can lead to differences in the synthesis of these silicon-organic compounds. So what now? “We need the best material for preserving cultural heritage, but the amounts required are fairly small,” explains Schottner. This makes material development and sales unprofitable for business-oriented companies. The executive board project and funding from the German Federal Environmental Foundation offered a way out of this dilemma. The ISC team analyzed the raw materials and the individual steps in their production down to the last detail of the chemical reactions, including moisture and temperature levels, and examined the impact of the various solvents on the final product. Now the process is nearly complete: the material is in the final testing phase, and the restorer in charge, Rainer Richter from the Dresden State Art Collections, is extremely satisfied.