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Web Date: May 26, 2011

Early Diagnosis For Aging Art

Cultural Conservation: New technique pinpoints early stages of chemical degradation in cultural artifacts
Department: Science & Technology
News Channels: Analytical SCENE
Keywords: near infrared spectroscopy, plastics, iron gall ink
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INSIDE SECRETS
A near infrared map (right) of buttons (left) shows that some are made of wood (right, blue), while others contain polyester (right, bright green).
Credit: Anal. Chem.
buttons
 
INSIDE SECRETS
A near infrared map (right) of buttons (left) shows that some are made of wood (right, blue), while others contain polyester (right, bright green).
Credit: Anal. Chem.

Long before museumgoers can see plastic crumble or ink fade on cultural artifacts, chemical degradation may have started inside the objects. But conservators hope that an early warning of breakdown would allow them to intervene before the damage was irreversible. With this hope in mind, European researchers have built a diagnostic tool that can sound the alarm when valuable objects are succumbing to the forces of time (Anal. Chem., DOI: 10.1021/ac200986p).

The researchers, led by Matija Strlič at the Centre for Sustainable Heritage at University College London, combined near infrared spectroscopy and a digital camera to produce two-dimensional chemical maps of objects. With these maps, conservators could assess whether an artifact was starting to degrade and if so, where the degradation was happening.

Strlič applied this technology to plastic artifacts and iron gall ink, which are two of the most vulnerable materials in museums, galleries, and archives, he says. The technique identified the chemical composition of plastic and polymer artifacts, including cellulose esters, polyurethanes, and hydrocarbons. The chemical maps also revealed that plasticizers were migrating out of polymers, which can lead to shrinking and cracking of the plastic. Finally, the researchers used the technique to measure the vulnerability of iron gall ink by quantifying the nearby pH. The ink, which was used for centuries to write many important documents, degrades faster in acidic conditions.

"Like a disease, chemical degradation advances quietly without any external signs," Strlič says, and then suddenly cracks form and information is lost. Now conservators can non-destructively watch chemical degradation proceed and pinpoint degradation hotspots, he adds.

 
Chemical & Engineering News
ISSN 0009-2347
Copyright © American Chemical Society

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